Showing papers in "Reproduction in 1996"
TL;DR: Bovine oocytes from prolonged dominant follicles undergo premature maturation in vivo, which perhaps accounts for the poor fertility observed in other studies when oestrous synchronization with progestins prolongs follicle lifespan.
Abstract: Prolonging the lifespan of bovine follicles is known to result in reduced fertility after ovulation and insemination. In this study, the effect of prolonged development of follicles on oocyte viability was examined. In Expt 1, six cows in the aspirated-prolonged-follicle group received a vaginal progesterone releasing device on day 4 of the oestrous cycle (day 1 = ovulation) and prostaglandin F2 alpha (40 mg) on day 6. Ultrasound-guided follicular aspiration was performed on day 13. Six cows in the aspirated-growing-follicle group received prostaglandin F2 alpha on day 6, and follicular aspiration on day 7. In Expt 2, all cows were stimulated with 36 mg FSH-P to develop multiple large follicles for study. Three cows in the prolonged-multiple-follicle group received the same treatment as did cows in Expt 1, but were ovariectomized on day 13. Three cows in the growing-multiple-follicle group received prostaglandin F2 alpha on day 6 and were ovariectomized on day 7. Oocytes recovered in both experiments were stained to reveal the stage of nuclear development. All oocytes from aspirated-prolonged and prolonged-multiple follicles showed expanded cumulus cells and condensed chromatin dispersed in the ooplasm, with possible germinal vesicle breakdown. Oocytes from aspirated-growing and growing-multiple follicles showed compact cumulus cells and an intact germinal vesicle. Plasma concentrations of oestradiol in both growing follicle groups increased until oocyte recovery. Oestradiol in the aspirated-prolonged-follicle group increased after luteolysis on day 6 and remained high until follicular aspiration. In contrast, in the FSH-stimulated prolonged-multiple-follicle group, oestradiol fell to trace amounts on day 8 and remained low. Oestradiol concentrations in follicular fluid were consistent with plasma concentrations for all groups. Bovine oocytes from prolonged dominant follicles undergo premature maturation in vivo, which perhaps accounts for the poor fertility observed in other studies when oestrous synchronization with progestins prolongs follicle lifespan.
321 citations
TL;DR: The data revealed that bovine embryos were dependent on oxidative phosphorylation for energy (ATP) production at all stages of pre-elongation development, with perhaps a shift in dependence towards glycolysis in conjunction with compaction.
Abstract: The consumption of oxygen, uptake of pyruvate and glucose and production of lactate were determined for groups of bovine embryos produced in vitro from the one-cell to the blastocyst stage (day 0-6 of culture). Measurements were made in Hepes-buffered synthetic oviduct fluid medium supplemented with 1.0 mmol pyruvate l-1, 10 mmol D,L-lactate l-1 and 1.5 mmol glucose l-1 and also 3 mg BSA ml-1 and, from day 5 of development, 10% (v/v) fetal calf serum. The amount of ATP production was determined from oxygen consumption and the proportion of glucose taken up that could be accounted for by lactate production. The data revealed that oxygen consumption was relatively constant from days 0-4 of culture (0.24-0.27 nl per embryo h-1), but increased with the initiation of compaction (0.39 nl per embryo h-1) and continued to increase with the formation and expansion of the blastocoel (0.9 nl per embryo h-1). Both pyruvate and glucose uptake followed similar patterns. Furthermore, when plotted against oxygen consumption, both pyruvate and glucose uptake increased significantly (P < 0.001) in a linear relationship (R2 = 0.61 and 0.49, respectively). Lactate production also increased with development and accounted for 40% of glucose uptake at day 0 of culture (putative zygotes), increasing to 70% by day 2 (eight-cell stage) and 100% of glucose uptake from day 4 of culture onwards. ATP production followed a similar pattern to that of oxygen consumption (60-85 pmol per embryo h-1 from day 0 to day 4) increasing with compaction (124 pmol per embryo h-1) and blastulation (221 pmol per embryo h-1). For precompaction stages, 93-96% of ATP production was derived from oxidative phosphorylation, decreasing to 82% with compaction. ATP produced by oxidative phosphorylation could be accounted for by the uptake of pyruvate, suggesting that bovine embryos produced in vitro utilize little endogenous substrates when appropriate exogenous substrates are present in the culture medium. The data revealed that bovine embryos were dependent on oxidative phosphorylation for energy (ATP) production at all stages of pre-elongation development, with perhaps a shift in dependence towards glycolysis in conjunction with compaction. It follows that oxidizable substrates, such as pyruvate and certain amino acids, are preferred in embryo culture medium during development in vitro.
319 citations
TL;DR: Female reproductive success varies with social rank in many gregarious mammals, including primates, ungulates and carnivores, and fertility among high-ranking females appeared to be less vulnerable to fluctuations in the food supply than was that among low- ranking females.
Abstract: Female reproductive success varies with social rank in many gregarious mammals, including primates, ungulates and carnivores. Social groups of spotted hyaenas (Crocuta crocuta) are structured by hierarchical dominance relationships that determine individuals' priority of access to food and other resources. The influence of female social rank on several measures of reproductive success was examined in a population of free-living Crocuta in Kenya. The study population was continuously observed for seven years, making it possible to document litter sizes, interbirth intervals, ages of cubs at weaning, intervals between weaning one litter and conceiving the next, annual rates of production of cubs, and survival of offspring to reproductive maturity. The relationship between availability of food, social rank, and female fertility was examined by monitoring abundance of prey throughout the study period. Most measures of reproductive performance were strongly influenced by social rank. High-ranking females began breeding a younger ages, were more frequently able to support pregnancy and lactation concurrently experienced shorter intervals between litters, and produced more surviving offspring than did lower-ranking females. Low-ranking females exhibited better reproductive performance when prey animals were abundant than when prey were relatively scarce. By contrast, reproductive performance among high-ranking females was always superior to that exhibited by low-ranking females, and did not vary with prey abundance. Fertility among high-ranking females thus appeared to be less vulnerable to fluctuations in the food supply than was that among low-ranking females.
240 citations
TL;DR: The findings indicate that testicular morphology and functions are affected by severe selenium deficiency and that the element is necessary for testosterone biosynthesis and the formation and normal development of spermatozoa.
Abstract: For four generations rats were fed a low selenium diet (2-7 micrograms Se kg-1) or the same diet with 250 or 300 micrograms Se kg-1 added as selenite. In male rats of the first generation that had been fed the diets from the age of 20 days onwards, selenium depletion led to slightly delayed testis growth during pubertal development that was compensated for in the later stages of maturation. In adult rats fed the low selenium diet for nearly a year no changes in testicular mass and morphology were observed. The serum concentration of testosterone of 6-month-old, selenium-depleted animals was, however, slightly lower than that of adequately supplied controls, and the stimulation of testosterone secretion by administration of GnRH or LH resulted in a significantly less marked rise in the serum concentration of testosterone. From the second generation onwards the testis mass, expressed as a percentage of the body mass, decreased and in the fourth generation was less than 50% of that of the controls. The male gonads of fourth generation animals showed a severe bilateral atrophy, in which the seminiferous tubules were considerably reduced in diameter and almost entirely lined by Sertoli cells and a few stem cells. Differentiated spermatozoa could not be detected. The alterations were reversible and spermatogenesis was restored by feeding the selenium-adequate diet. The findings indicate that testicular morphology and functions are affected by severe selenium deficiency and that the element is necessary for testosterone biosynthesis and the formation and normal development of spermatozoa.
223 citations
TL;DR: It was found that the characteristic increase in uterine expression of mRNA encoding GM- CSF and release of GM-CSF bioactivity from uterine epithelial cells into the luminal cavity seen after mating with intact or vasectomized males was no longer evident in matings with male mice from whom the seminal vesicles had been surgically removed.
Abstract: Mating evokes a characteristic pattern of molecular and cellular events in the rodent reproductive tract, including an infiltration of the endometrial stroma and uterine lumen with activated macrophages and granulocytes, which closely resembles a classic inflammatory response. Previous studies in mice indicate that these cellular changes are associated with, and are largely a consequence of, an upregulated synthesis and release of granulocyte-macrophage colony-stimulating factor (GM-CSF) from the uterine epithelium in response to seminal fluid. The aim of this study was to investigate further the origin and nature of the factors present in seminal fluid that trigger the GM-CSF response. It was found that the characteristic increase in uterine expression of mRNA encoding GM-CSF and release of GM-CSF bioactivity from uterine epithelial cells into the luminal cavity seen after mating with intact or vasectomized males was no longer evident in matings with male mice from whom the seminal vesicles had been surgically removed. The extent of inflammatory leucocyte infiltration into the endometrium was also reduced ; the most notable effect was a complete absence of the exocytosis of neutrophils into the luminal cavity normally seen after matings with intact or vasectomized males. Bioassay of the GM-CSF output of oestrous endometrial cells after culture with crude or Sephacryl S-400 chromatographed fractions of seminal vesicle fluid showed that the GM-CSF stimulating activity was predominantly associated with protein moieties in seminal vesicle fluid of approximately 650 000 M r and 100 000-400 000 M r . These data confirm the presence in seminal vesicle fluid of specific factors that initiate an inflammatory response in the uterus after mating through upregulating GM-CSF synthesis in the uterine epithelium. The significance of the cytokine release and cellular changes induced by seminal plasma for implantation of the conceptus and pregnancy outcome remain to be determined.
194 citations
TL;DR: The data suggest that in rapidly growing adolescent ewes, the established anabolic drive to maternal tissue synthesis is maintained at the expense of the gradually evolving nutrient requirements of the gravid uterus, resulting in a major restriction in placental growth and a highly significant decrease in birthweight.
Abstract: A highly controlled model to investigate nutrient partitioning and the control of fetal growth in the rapidly growing adolescent sheep is described. Embryos recovered from superovulated adult ewes inseminated by a single sire were transferred in singleton to the uterus of prepubertal adolescent recipients induced to ovulate at 21 weeks of age (liveweight 44.4 +/- 0.38 kg). After embryo transfer, the adolescent recipients were individually offered a high (n = 28) or low (n = 20) quantity of a complete diet calculated to achieve rapid (RMG) or normal (NMG) maternal growth rates. After day 100 of gestation the feed intake of the NMG group was adjusted weekly to meet the increasing nutrient demands of the gravid uterus. The proportion of adolescent recipients initially conceiving was significantly (P < 0.01) influenced by maternal nutrient intake and was lower in the RMG (0.57) than in the NMG (0.85) group. For adolescent dams that maintained their pregnancies, liveweight gain during the first 95 days of gestation was significantly (P < 0.001) higher in the RMG compared with the NMG group (234 +/- 9.5 and 75 +/- 5.0 g day-1, respectively). Rapid maternal growth rates were associated with a significant reduction in both fetal and placental weights as determined when the animals were killed on day 95 of gestation (n = 3 per group) or at term. For the RMG (n = 8) and NMG (n = 11) groups, respectively, mean lamb birthweights at term were 2.74 +/- 0.25 and 4.34 +/- 0.27 kg (P < 0.001), while term placental weights were 263 +/- 16.8 and 438 +/- 44.6 g (P < 0.002). The number of fetal cotyledons per placenta and mean fetal cotyledon weight were significantly lower in RMG compared with NMG ewes (P < 0.05). Irrespective of treatment group, lamb birthweight was highly positively correlated with placental weight and both parameters were negatively correlated with maternal liveweight gain during the first 100 days of gestation. The incidence of non-infectious spontaneous abortion at 125 +/- 1.3 days of gestation was higher (P < 0.001) in the RMG (4 of 12) than in the NMG (1 of 12) group. Similarly, duration of gestation for those ewes delivering live young was shorter (P < 0.01) in the RMG compared with the NMG group (140 +/- 0.94 versus 143 +/- 0.28 days). Colostrum yield at parturition was positively related to placental weight and significantly lower (P < 0.001) in the RMG than in the NMG group (35 +/- 12.1 and 247 +/- 36.2 g, respectively). Neonatal survival rates at 72 h after parturition were reduced (P < 0.05) in the RMG (38%) compared with the NMG group (91%). These data suggest that in rapidly growing adolescent ewes, the established anabolic drive to maternal tissue synthesis is maintained at the expense of the gradually evolving nutrient requirements of the gravid uterus. This results in a major restriction in placental growth and a highly significant decrease in birthweight.
186 citations
TL;DR: A serum-free ovine granulosa cell culture system is described that allows the induction of FSH-responsive oestradiol production by undifferentiated cells from small (< 3.5 mm) follicles and the maintenance of oest radionuclide production by differentiated cells from large (> or = 3. 5 mm) hair follicles to study, in vitro, the cascade of events that controls granul Rosa cell differentiation and ultimately follicle selection in sheep.
Abstract: A serum-free ovine granulosa cell culture system is described that allows the induction of FSH-responsive oestradiol production by undifferentiated cells from small ( < 3.5 mm) follicles (P < 0.001) and the maintenance of oestradiol production by differentiated cells from large (\m=ge\3.5mm) follicles. Physiological doses of FSH stimulated (P<0.01) proliferation of cultured granulosa cells from both small and large follicles. The synthesis of immunoreactive inhibin and progesterone by granulosa cells from small and large follicles increased (P < 0.01) with time of culture, and was not dependent on FSH. Inhibin secretion expressed on a per cell basis was not FSH responsive. Insulin and insulin-like growth factor I (IGF-I), in the presence of FSH, stimulated (P < 0.001) cell proliferation and oestradiol and inhibin production by granulosa cells from small and large follicles. There was a significant (P< 0.001) interaction between insulin and IGF-I in the stimulation of granulosa cell proliferation and differentiation. Both epidermal growth factor (EGF) and transforming growth factor \g=a\(TGF-\g=a\)in the presence of FSH stimulated cellular proliferation (P< 0.001) in a dose-responsive manner and concomitantly inhibited (P< 0.001) oestradiol and inhibin secretion. The development of this granulosa cell culture system will make it possible to study, in vitro, the cascade of events that controls granulosa cell differentiation and ultimately follicle selection in sheep.
165 citations
TL;DR: The differences in transcription between bovine embryos derived in vivo or in vitro indicate that culture conditions affect gene expression and contributes towards physiological characterization by definition of transcription phenotype of bovines produced in vitro.
Abstract: In this study we have examined the presence of mRNA encoding connexin 43 (Cx43) in bovine embryos derived in vivo and in vitro. Cumulus-oocyte complexes, immature and matured oocytes liberated from cumulus cells, zygotes, 2-4-cell and 8-16-cell embryos, morulae, blastocysts and hatched blastocysts were produced in vitro from ovaries obtained from an abattoir using TCM 199 supplemented with hormones and 10% oestrous cow serum for maturation. Cumulus-oocyte complexes matured for 24 h were exposed to bull spermatozoa for 19 h and then cultured in TCM 199 supplemented with 10% oestrous cow serum to the desired developmental stage. Morulae and blastocysts derived in vivo were collected from superovulated donor cows. Total RNA was extracted from pools of 60-200 bovine oocytes or embryos using a modified phenol-chloroform extraction method and analysed by reverse transcriptase polymerase chain reaction. Before reverse transcription, aliquots of DNase-digested embryonic RNA were tested by polymerase chain reaction using bovine-specific primers to control for residual genomic DNA contamination. DNA-free, total RNA was reverse transcribed after preincubation with the Cx43 specific 3'primer. The resultant cDNA was amplified by polymerase chain reaction using Cx43 specific primers that define a 516 bp fragment of Cx43. The reverse transcriptase polymerase chain reaction product was verified by restriction enzyme analysis with Alu I and sequencing. Assays were repeated at least twice for each developmental stage and provided identical results between replicates. Cx43 transcripts were detected in bovine morulae and blastocysts grown in vivo. In contrast, whereas the early in vitro stages from cumulus-oocyte complexes to morulae expressed Cx43, blastocysts and hatched blastocysts did not have detectable concentrations of mRNA from this gene. Restriction enzyme cutting revealed three fragments of the predicted size (139, 177, 200 bp). The amplified product showed 100% identity with the published bovine genomic DNA sequence. Under our in vitro conditions the Cx43 gene either had never been activated, which would require that the maternal transcript was stable through early development, or embryonic gene expression that had been active was then terminated prematurely. The differences in transcription between bovine embryos derived in vivo or in vitro indicate that culture conditions affect gene expression. This affords a tool for the further optimization of in vitro production systems for bovine embryos and contributes towards physiological characterization by definition of transcription phenotype of bovine embryos produced in vitro.
164 citations
TL;DR: Data indicate that increased blood pressure in rats is linked to disproportionate patterns of growth in middle and late gestation, and rats exposed to low protein diets in utero had significantly higher systolic blood pressure relative to control animals.
Abstract: In human populations, patterns of disproportionate fetal growth are associated with cardiovascular disease in later life. Protein restriction of pregnant rats is known to impair fetal growth and is also associated with increased systolic blood pressure in later life. Growth of fetuses exposed to maternal low protein diets was found to be accelerated between day 14 and day 20 of gestation, but this growth appeared to falter in late gestation, resulting in low or normal birthweights. Placental growth was also accelerated by protein restriction. Day 20 fetuses from rats fed low protein diets were heavier but had proportionally smaller brains than did control fetuses. These animals were also longer in proportion to body mass. Between day 20 and full term (day 22), growth of the brain was spared at the expense of the trunk and at birth, pups exposed to low protein were short in relation to body mass. At weaning, rats exposed to low protein diets in utero had significantly higher systolic blood pressure relative to control animals. These data indicate that increased blood pressure in rats is linked to disproportionate patterns of growth in middle and late gestation.
160 citations
TL;DR: It is demonstrated that cryopreserved fetal ovarian tissue can be transplanted to adult recipients with subsequent restoration of fertility and that this process is dependent on the absence of the ovaries of the recipients.
Abstract: Sixteen-day-old fetal mouse ovaries were slowly frozen in 1.5 mol dimethylsulfoxide ml-1 and subjected to one of two thawing procedures--fast thaw or slow thaw. Fresh and frozen-thawed fetal ovaries were transplanted orthotopically (to the bursal cavity) to either bilaterally or unilaterally ovariectomized adult female recipients. Fresh fetal ovaries were also transplanted heterotopically (under the kidney capsule) to intact, bilaterally or unilaterally ovariectomized adult females. Transplantation of fetal ovaries to bilaterally ovariectomized adult recipients resulted in restoration of cyclic activity within 20.5 +/- 4.7 (mean +/- SEM) days or 23.4 +/- 0.8 days in orthotopic and heterotopic groups, respectively. Developing follicles and corpora lutea were observed within 4 weeks after transplantation of fetal ovaries to heterotopic sites and within 6 weeks after transplantation to orthotopic sites. After orthotopic transplantation, 33% of the recipients became pregnant. Orthotopic or heterotopic transplantation to intact of unilaterally ovariectomized recipients resulted in quiescence of the fetal ovary. After cryopreservation, transplantation of fetal ovaries to bilaterally ovariectomized recipients resulted in restoration of cyclic activity within 19.3 +/- 2.1 days and 23.4 +/- 5.1 days after transplantation in slow thaw and fast thaw groups, respectively. Fertility was restored to 86% of fast thawed and 25% of slow thawed fetal ovary transplants to bilaterally ovariectomized adult recipients. No ovarian tissue was observed on the side of the fetal graft in unilaterally ovariectomized recipients that received frozen-thawed fetal ovaries. These results demonstrate that cryopreserved fetal ovarian tissue can be transplanted to adult recipients with subsequent restoration of fertility and that this process is dependent on the absence of the ovaries of the recipients.
152 citations
TL;DR: Monitoring of cheetahs confirmed that the cheetah is polyoestrus and ovulation is almost always induced, however, new evidence suggests that many females inexplicably experience periods of anoESTrus unrelated to season, while 25% of theCheetahs examined expressed no ovarian activity during the study period.
Abstract: Faecal oestradiol and progestogen metabolite excretion was monitored in adult, female cheetahs (Acinonyx jubatus) (n = 26) for 1-24 months. Increased faecal oestradiol excretion was associated with mating or equine chorionic gonadotrophin (eCG) administration for artificial insemination, whereas increased progestogen metabolites were observed during natural and human chorionic gonadotrophin (hCG)-induced pregnant and nonpregnant luteal phases. On the basis of oestradiol excretory patterns, duration of the oestrous cycle (mean +/- SEM) was 13.6 +/- 1.2 days with high oestradiol concentrations lasting for 4.1 +/- 0.8 days. In non-gonadotrophin-treated cheetahs, 75% showed evidence of oestrous cyclicity; however, none evaluated for 1 year or longer were continuously cyclic. Rather, cyclicity was interrupted by periods of anoestrus, often exceeding several months in duration. These inactive ovarian periods were unrelated to season and were not synchronous among females. Mean duration of gestation (breeding to parturition) was 94.2 +/- 0.5 days, whereas duration of faecal progestogen metabolite excretion during the nonpregnant luteal phase was 51.2 +/- 3.5 days. On the basis of progestogen metabolite evaluations, spontaneous ovulation (non-mating induced) occurred only once in two females (2 of 184 oestrous cycles; 1.1%). Peak eCG-stimulated, preovulatory oestradiol concentrations were similar to those associated with natural oestrus, whereas progestogen metabolite profiles after hCG resembled those during pregnant and nonpregnant luteal phases after natural mating. In summary, results confirm that the cheetah is polyoestrus and ovulation is almost always induced. However, new evidence suggests that many females inexplicably experience periods of anoestrus unrelated to season, while 25% of the cheetahs examined expressed no ovarian activity during the study period.
TL;DR: It is concluded that in vitro maturation and fertilization compromise subsequent embryonic and fetal development in sheep irrespective of the subsequent in vivo or in vitro culture treatment.
Abstract: The influence of various in vitro procedures on embryo survival and the production of normal offspring was investigated in sheep. Zygotes produced from in vitro matured (IVM) and fertilized (IVF) oocytes derived from slaughtered Merino ewes were allocated to three culture treatments for 6.5 days. Two groups were cultured in vitro in the absence or presence of oviduct epithelial cells while the third group was cultured in vivo in the oviducts of synchronized ewes. A fourth group of zygotes obtained from superovulated Merino ewes was also cultured in vivo and served as controls. After culture, IVM-IVF morulae and blastocysts, and control embryos were transferred to final recipient ewes. Pregnancy was diagnosed at day 50 of gestation by ultrasonography and pregnancies were allowed to go to term. The survival to term of IVM-IVF zygotes cultured in vitro was reduced compared with both in vivo cultured IVM-IVF zygotes and control zygotes (25-35% versus 51-60%, respectively, P 0.1). Both the gestation period and birth weight of IVM-IVF lambs were increased when compared with controls, the former significantly in all groups (154.0-154.9 days versus 150.6 days; P < 0.01), while the latter increase was on the borderline of significance (4.5-4.8 kg versus 4.0 kg; 0.01 < or = P < or = 0.1, respectively) and dependent on the prolongation of the gestation period. It is concluded that in vitro maturation and fertilization compromise subsequent embryonic and fetal development in sheep irrespective of the subsequent in vivo or in vitro culture treatment. Subjecting IVM-IVF zygotes to in vivo culture for 6.5 days minimizes only some of these effects, thus leading to the aberrant production of some offspring.
TL;DR: Surges in FSH concentrations occurred throughout pregnancy, but during the last 30 days of pregnancy the number of surges was reduced and each heifer had one or two ineffective surges (no follicular wave detected).
Abstract: Follicles were monitored daily by ultrasound and blood samples for FSH assay were collected daily from eight heifers from day 90 of pregnancy to the emergence of the first postpartum follicular wave. Follicles > or = 6 mm in diameter emerged in groups or waves in each heifer (P or = 6 mm were not detected during the last 21.6 +/- 2.4 (mean +/- SEM) days of pregnancy. The characteristics of the first follicular wave after day 90 were similar to previous reports for days 10-100. However, between months 4 (days 90-119) and 5, there was a decrease (P 5 mm). In association with waves in which the largest follicle reached > or = 10 mm compared with 6-9 mm, there was greater depression in the FSH nadir, longer intervals from FSH peak to nadir, and longer intervals between adjacent FSH peaks and adjacent waves.
TL;DR: It is indicated that domestic cat oocytes reach nuclear maturity by 24 h in culture and can be fertilized and develop to blastocysts optimally after insemination at 32 h.
Abstract: Four experiments determined the kinetics of in vitro maturation and fertilization of cat oocytes and the effects of prolonged cold storage of ovaries before oocyte recovery on in vitro maturation/in vitro fertilization (IVM/IVF) success. Domestic cat ovaries were collected at ovariohysterectomy and stored at 4 degrees C in PBS until oocyte recovery and culture in Eagle's minimal essential medium (EMEM) containing FSH, LH, oestradiol and BSA for maturation. In Expt 1, meiotic maturation was assessed at 0, 12, 24, 38 and 48 h of culture. After 24 h, > 61% of oocytes were in telophase I or metaphase II. In Expt 2, oocytes were recovered from ovaries stored for 24, 48 or 72 h and cultured in EMEM for 24 h. There was no difference among groups (P > 0.05) in the ability to achieve nuclear maturation (mean +/- SEM, 57.1 +/- 5.3%, 60.4 +/- 5.4%, 55.4 +/- 15.1% for 24, 48 and 72 h, respectively). Fertilization and embryo development after insemination at 16, 24, 32, 40 and 48 h of culture were examined in Expt 3. Of 98 oocytes inseminated at 32 h, 69% cleaved, 59% developed into morulae and 13% into blastocysts, more (P < 0.05) than those oocytes inseminated at earlier and later times. Development to blastocysts occurred after insemination at 16 (1.2%), 24 (9.1%) and 32 (13.3%) h of culture, but not after insemination at 40 or 48 h. Expt 4 involved cold storage of ovaries for 24, 48 or 72 h before oocyte recovery and insemination at 32 h of culture (the optimal time measured in Expt 3). Compared with storage for 24 h, fertilization success was lower (P < 0.05) in the 48 and 72 h groups, and, although 9.1% of inseminated oocytes from the 24 h storage group developed to blastocysts, none (P < 0.05) achieved this stage after 48 or 72 h of storage. These results indicate that domestic cat oocytes reach nuclear maturity by 24 h in culture and can be fertilized and develop to blastocysts optimally after insemination at 32 h. Oocytes recovered from ovaries stored at 4 degrees C for up to 72 h are capable of reaching telophase I or metaphase II in vitro. However, only oocytes stored within the ovary for 24 h produce blastocysts, indicating that the ability to achieve nuclear maturation is an inadequate indicator of fertilization and developmental competence.
TL;DR: The results indicated that the optimum time to mate or attempt to induce ovulation in the female dromedary is when the growing follicle measures 0.9-1.9 cm in diameter, which is close to the maximum diameter required for ovulation.
Abstract: \m=+-\ 1.0 days. Mean \m=+-\sem serum concentrations of oestradiol reached peak values at 39.0 \m=+-\1.8 pg ml \m=-\1, when the dominant follicle measured 1.7 \m=+-\0.1 cm and, after ovulation, mean serum concentrations of progesterone reached peak values at 2.6 \m=+-\0.3 ng ml \m=-\1on day 8, before decreasing to 3.0 cm ovulated in response to any of the treatments. These results indicated that the optimum time to mate or attempt to induce ovulation in the female dromedary is when the growing follicle measures 0.9\p=n-\1.9cm in diameter.
TL;DR: The production of spermatozoa in roe deer is intensified by enlargement of gonads as well as enhanced efficiency of spermatogenesis during the rut, and testosterone seems to play a role in the regulation of both processes.
Abstract: Quantitative changes in testes of roe deer were studied during the annual cycle. Testicular spermatozoa were counted and proportions of different cell types were estimated using DNA flow cytometry. A proliferation-specific antigen of somatic cells was evaluated by an immunoradiometric assay. Apoptosis was examined by cell death detection ELISA, and testosterone concentrations were measured with an enzymeimmunoassay. The testis mass of adults reached a maximum during the rut from mid-July to mid-August. Gonadal size corresponded to numbers of testicular spermatozoa g-1 testis. In the rutting period, epididymal spermatozoa were of the highest morphological and functional competence. The proportions of haploid (1c), diploid (2c) and tetraploid (4c) cells changed over time with the maximum of 1c cells during the breeding period. Meiotic division (1c:4c ratio) increased sharply immediately before rut, while mitosis (% cells in G2-M phase) was already high during spring. Proliferation and apoptosis revealed an opposite pattern during the annual cycle; the most intensive apoptosis occurred during the time of testis involution. Testosterone production showed a biphasic pattern. It dropped rapidly from the highest value in August to very low concentrations thereafter. Yearlings were characterized by smaller peaks of testicular growth and sperm production. Fawns started testicular growth and meiosis in winter. In conclusion, the production of spermatozoa in roe deer is intensified by enlargement of gonads as well as enhanced efficiency of spermatogenesis during the rut. Interrupted proliferation and stimulated apoptosis promote testis involution after the rut, and testosterone seems to play a role in the regulation of both processes.
TL;DR: Evidence is provided supporting a role for metalloproteinases in endometrial biology, not only in matrix remodelling during the cycle, but also in glandular secretions potentially relevant to blastocyst recognition and implantation.
Abstract: Immunolocalization techniques were used to examine the distribution of the matrix metalloproteinases gelatinase B and stromelysin 1 in human endometrial specimens, taken across the normal menstrual cycle. Gelatinase B was produced by glandular epithelial cells for approximately 7 days during the proliferative phase, with polymorphonuclear leucocytes, macrophages and eosinophils providing most of this enzyme at menstruation. There was no evidence that gelatinase B is produced by stromal cells or mast cells during the cycle. Immunoreactive gelatinase B in glandular epithelial cells was greatest during the late proliferative phase and just after ovulation; its presence in glandular secretion and the uterine fluid was optimal during the peri-implantation phase. Gelatinase B was clearly associated with an influx of polymorphonuclear leucocytes, macrophages and eosinophils just before, and during, menstruation. In contrast, immunostaining for stromelysin 1 was much weaker than that for gelatinase B, and was present only around stromal cells and limited to microfocal locations at times coincident with stromal oedema (days 8-10 and 21-22). Both enzymes were widely distributed in specimens just before and during menstruation, and were particularly prominent in connective tissue stroma and vascular basement membranes. Specimens at the early proliferative stage were devoid of both enzymes. The data provide further evidence supporting a role for metalloproteinases in endometrial biology, not only in matrix remodelling during the cycle, but also in glandular secretions potentially relevant to blastocyst recognition and implantation. Our observations emphasize the functional importance of specific cell types and the temporal regulation of gelatinase B and stromelysin 1 throughout the normal menstrual cycle.
TL;DR: The integrity of the plasma membrane of boar spermatozoa was found to be dependent on temperature, donor and osmolality, decreasing significantly below room temperature, and below 185 mOsmol kg-1 (P < 0.05).
Abstract: A series of six experiments was conducted to determine the fundamental cryobiological properties of boar spermatozoa to develop optimal approaches for cryopreserving this important cell type. In the first experiments, boar spermatozoa samples were diluted in various osmolalities of experimental solutions (185-900 mOsmol kg-1) to provide hypo-, iso-, and hyperosmotic conditions. Equilibrium cell volumes (Expts 1 and 2) were measured after exposure for 3 min and the change in cell volume was measured over time using an electronic particle counter (Expt 3). The isosmotic cell volume was found to be 26.3 +/- 0.39 microns 3 (mean +/- SEM; n = 5). Over this range of osmolalities, boar spermatozoa behaved as linear osmometers (a linear volume versus 1/osm plot, r2 = 0.99) with an osmotically inactive cell fraction of 67.4 +/- 4.5%. The rate of water permeability (Lp) was determined to be 1.03 +/- 0.05 microns min-1 atm-1, which was consistent within and among donors (P > 0.130). A second series of experiments was performed to determine the effect of temperature and osmolality on boar sperm motility (Expt 4), and the effect of osmolality on the integrity of the sperm plasma membrane and its temperature dependence. Plasma membrane integrity was measured before and after boar spermatozoa were returned to an isosmolality (Expt 6). Motility was not affected at 30 degrees C, relative to that at room temperature, but was significantly decreased (P 0.05) until the osmolality reached 210 mOsmol kg-1, at which time motility began to decrease from 95% to 10% of the original value at 90 mOsmol kg-1. The integrity of the plasma membrane of boar spermatozoa was found to be dependent on temperature, donor and osmolality, decreasing significantly (P 0.10) in the integrity of the plasma membrane of the samples before and after returning to 290 mOsmol kg-1, indicating that osmotic damage occurs during the initial change from isosmotic to hyposmotic media. These osmotic characteristics could be used to determine optimal conditions for cryopreservation of boar spermatozoa.
TL;DR: A significantly (P < 0.001) higher percentage of normal sperm heads were found in the fertile group than in the subfertile group of stallions (52% versus 19%).
Abstract: The heads of stallion spermatozoa were analysed by computer automated sperm head morphometry and the morphometric values of the major subpopulations of sperm heads were assessed. The criteria for normal dimensions of stallion sperm heads are proposed based on the analysis of these measurements. Semen samples were collected from 10 fertile and 10 subfertile stallions, processed by a standard method, smeared onto microscope slides and stained using haematoxylin. At least 200 properly digitized sperm heads were analysed from each stallion. The measurements for length, width, area, perimeter and width/length were recorded for each stallion. All sperm head measurements were placed in a statistical database and multivariate cluster analysis performed. Mean measurements for all parameters of the major clusters of fertile and subfertile stallions were compared by analysis of variance. The ranges of the values of the major clusters of fertile stallions were applied to all stallions to determine the percentage of normal sperm heads for each stallion. The mean values for length, width, area and perimeter in the major cluster of sperm head dimensions of fertile stallions were significantly different from those of the subfertile stallions (P < 0.001). The range of values of the major cluster of fertile stallions was length = 4.9-5.7 microns, width = 2.5-3.0 microns, width/length = 0.45-0.59, area = 10.3-12.1 microns2, and perimeter = 12.9-14.2 microns. On the basis of these values, a significantly (P < 0.001) higher percentage of normal sperm heads were found in the fertile group than in the subfertile group of stallions (52% versus 19%).
TL;DR: Results suggest that a factor from the oviductal secretion is required for the complete cortical granule reaction and in the modification of the zona pellucida.
Abstract: The effects of oviductal fluid on sperm penetration and cortical granule exocytosis in pigs were examined. Cortical granule exocytosis in oocytes matured in vivo and in vitro was observed by staining with fluorescent-labelled lectin and laser-scanning confocal microscopy. Exocytosis of matured oocytes was classified into three categories after in vitro fertilization : complete cortical granule exocytosis and even distribution of exudate in the entire perivitelline space (type I) ; complete exocytosis and partial distribution of exudate (type II) and incomplete cortical granule exocytosis (type III). The incidence of oocytes with type I exocytosis was higher in oocytes matured in vivo than in those matured in vitro. The addition of oviductal fluid at a concentration of 1% or 10% to the fertilization medium decreased sperm penetration and the mean number of spermatozoa present in penetrated eggs. The distribution of cortical granule exudate was not different in the presence of 1% oviductal fluid after sperm penetration from that of control groups. When oocytes were cultured for 1.5 h in medium containing 10% or 30% oviductal fluid before insemination, the incidence of monospermy increased without a decrease in sperm penetration. Preculture of oocytes in medium containing 30% oviductal fluid increased type I cortical granule reaction and increased resistance of the zona pellucida to dissolution by 0.1% (w/v) pronase at the time of sperm penetration. These results suggest that a factor(s) from the oviductal secretion is required for the complete cortical granule reaction and in the modification of the zona pellucida.
TL;DR: The changes in lipid composition owing to ageing were associated with a marked reduction within the spermatozoa of the major antioxidant enzyme glutathione peroxidase and the role of these changes in the specific combinations of polyunsaturated lipids and in antioxidant capacity in the reduction in fertility with age is discussed.
Abstract: Spermatozoa and seminal plasma from cockerels at the beginning and end of their reproductive periods were examined for their lipid composition and associated antioxidant capacities. The significant reduction in concentration of spermatozoa with age was associated with a large increase in lipid concentrations in spermatozoa and in seminal plasma. This change in lipid concentration was accompanied by increases in the proportions of phospholipid and free cholesterol; in contrast, the proportions of these lipid moieties in seminal plasma were reduced. The major phospholipid fractions in the spermatozoa and seminal plasma were phosphatidyl choline and phosphatidyl ethanolamine. There was a large decrease with age in the proportion of phosphatidyl ethanolamine and a commensurate increase in that of phosphatidyl choline in the spermatozoa and seminal plasma. These major changes in phospholipid content were accompanied by a decrease in the amount of phosphatidyl serine in the spermatozoa and increases in phosphatidyl inositol and cardiolipin in both spermatozoa and seminal plasma. The reductions in the proportions of phosphatidyl ethanolamine were accompanied by considerable reductions in the content of the major polyunsaturated fatty acids 20:4 (n-6) and 22:4 (n-6). The changes in lipid composition owing to ageing were associated with a marked reduction within the spermatozoa of the major antioxidant enzyme glutathione peroxidase. The role of these changes in the specific combinations of polyunsaturated lipids and in antioxidant capacity in the reduction in fertility with age are discussed.
TL;DR: The present results suggest that changes in the extracellular matrix may play an important role in implantation, in invasion of trophoblastic cells and in the maintenance of pregnancy.
Abstract: The distribution of the extracellular matrix, including type I, III, IV and VI collagens and laminin, and of prolyl hydroxylase was investigated in the human endometrium by an indirect immunofluorescence method with specific monoclonal antibodies. Collagens were also extracted from the endometrial tissues in the proliferative and secretory phases and from the decidual tissues in the first trimester of pregnancy. Immunohistochemical studies demonstrated that interstitial collagens, such as type I, III, and VI collagens, were localized diffusely in the stroma of the endometrium throughout the menstrual cycle, as well as in the decidua. Type IV collagen and laminin were localized exclusively in the basement membrane of the endometrial glands and in the walls of blood vessels during the proliferative and secretory phases. However, strong staining for type IV collagen and laminin was recognized in the pericellular region of endometrial stromal cells in the decidua. Prolyl hydroxylase was localized in the cytoplasm of endometrial stromal cells and endometrial glandular cells during the menstrual cycle. Intense immunostaining for prolyl hydroxylase was observed in the decidual cells. However, immunoreactivity for prolyl hydroxylase in the endometrial glandular cells disappeared during the process of decidualization. The ratio of type III to type I collagen was significantly decreased (P < 0.05) and the ratio of type V to type I collagen was significantly increased (P < 0.01) in the decidua, as compared with ratios in the endometrium during the proliferative phase. The present results suggest that changes in the extracellular matrix may play an important role in implantation, in invasion of trophoblastic cells and in the maintenance of pregnancy.
TL;DR: It is concluded that ocelots are relatively insensitive to exogenous gonadotrophins, requiring much higher dosages (on a per body mass basis) to elicit an appropriate ovarian response than do any other felid species studied to date.
Abstract: Adult female ocelots (Felis pardalis) were treated with one of four dosages of equine chorionic gonadotrophin (eCG) and human chorionic gonadotrophin (hCG) (100 iu eCG/75 iu hCG, n = 3; 200 iu eCG/150 iu hCG, n = 4; 400 iu eCG/150 iu hCG, n = 5; 500 iu eCG/225 iu hCG, n = 5); hCG was administered 80 h after eCG. Ovaries of each animal were evaluated by laparoscopy 39-43 h after hCG, and blood was collected for progesterone and oestradiol analysis. With progressive increases in gonadotrophin dosage, female ocelots produced more (P or = 2 mm in diameter), ranging from 1.3 +/- 0.7 (mean +/- SEM) follicles per female at the lowest dosage to 8.8 +/- 2.8 follicles per female at the highest dosage. Similarly, ocelots produced more (P 0.05) of females ovulated in response to each dosage. At laparoscopy, serum concentrations of oestradiol (overall mean, 330.2 +/- 62.2 pg ml-1) and serum concentrations of progesterone (overall mean, 18.5 +/- 6.4 ng ml-1) in ovulating females did not differ (P > 0.05) across treatment groups. Ten ovulating ocelots were laparoscopically inseminated with fresh (4.7 +/- 0.2 x 10(6); n = 2 females) or frozen-thawed (10.7 +/- 1.8 x 10(6); n = 8 females), motile spermatozoa. One female treated with 500 iu eCG/225 iu hCG and inseminated with 7.5 x 10(6) motile, frozen-thawed spermatozoa conceived and gave birth to a healthy male kitten after a gestation of 78 days. We conclude that ocelots are relatively insensitive to exogenous gonadotrophins, requiring much higher dosages (on a per body mass basis) to elicit an appropriate ovarian response than do any other felid species studied to date. Nonetheless, the gonadotrophin-treated female can become pregnant and carry offspring to term after laparoscopic intrauterine insemination with frozen-thawed spermatozoa.
TL;DR: The increased number of type A spermatogonia and of Sertoli cells associated with larger testes for the Whitecross over West African or Meishan boars is sufficient to explain the higher sperm production in the WhiteCross.
Abstract: The objective of this study was to determine the number of Sertoli cells per boar, daily sperm production, and germ cell yield per type A spermatogonium in mature Whitecross, Meishan, and West African boars. The paired parenchymal mass was greatest in the Whitecross boars and greater in Meishan than in West African boars. Daily sperm production per boar (x 10(9)) differed significantly (P 0.05) across breeds during spermiogenesis, and on average amounted to 8.6%. The increased number of type A spermatogonia and of Sertoli cells associated with larger testes for the Whitecross over West African or Meishan boars is sufficient to explain the higher sperm production in the Whitecross. However, the lower index of degeneration and more efficient Sertoli cell function in Meishan boars results in the daily sperm production being intermediate between that of the Whitecross and West African boars.
TL;DR: It is demonstrated that VEGF is expressed in luteal tissue throughout the ovine oestrous cycle and that expression of mRNA encoding V EGF is upregulated during the period of rapid lutea development, when luteAL vascular growth is at its maximum.
Abstract: The corpus luteum undergoes tremendous growth, development and regression each oestrous or menstrual cycle. These changes are reflected by equally impressive growth and regression of the luteal vasculature. We have previously shown that angiogenic factors from corpora lutea are primarily heparin binding and that one of these factors is similar to vascular endothelial growth factor (VEGF). In an effort to identify this factor, and to define its role in luteal vascular development, the cDNA for the coding region of ovine VEGF was sequenced and a sensitive RNase protection assay was developed to quantitate mRNA encoding VEGF in luteal tissues from ewes in the early (days 2\p=n-\4),mid- (day 8) and late (days 14\p=n-\15)stages of the oestrous cycle. In addition, an N-terminal peptide was synthesized from the translated ovine cDNA sequence for VEGF and an antiserum was raised against this peptide for use in western immunoblotting procedures. Nested reverse transcriptase (RT)-PCR of RNA from ovine corpora lutea resulted in three products that correspond in size to the alternatively spliced variants of VEGF VEGF120, VEGF164, and VEGF188) predicted from other species. The RNase protection assay revealed that the proportion of mRNA encoding VEGF was 2- to 3-fold greater on days 2\p=n-\4than on day 8 or days 14\p=n-\15.Densitometric analysis of gels from the RNase protection assay showed that VEGF120 represented approximately one third of the total mRNA encoding VEGF in the corpus luteum and that this proportion did not vary with stage of the oestrous cycle. SDS-PAGE and western immunoblot analysis of a homogenate from corpora lutea showed a single 18 kDa protein. These data demonstrate that VEGF is expressed in luteal tissue throughout the ovine oestrous cycle and that expression of mRNA encoding VEGF is upregulated during the period of rapid luteal development, when luteal vascular growth is at its maximum.
TL;DR: It is concluded that social status exerts a major impact on paternity by affecting the number of females mated with, that male quality is a critical factor modulating paternity, and that male feeding strategies have a direct influence on variation in male reproductive success.
Abstract: When females mate with several males, problems arise in identifying sire and in determining factors contributing to differential male reproductive success. Three potential primary correlates of differential reproduction in males include fighting ability, sperm competition, and body condition. We collected a variety of socioendocrine and morphological measurements from sexually mature rhesus macaques to determine corollaries of paternity. We studied a troop of about 150 rhesus macaques living in a 0.3 ha corral and identified the sires of 70% of infants using multilocus DNA fingerprints. Eight of 21 males sired offspring, and dominant males were more successful than subordinate males. Neither canine size nor age influenced the probability of siring offspring. Male reproductive success was primarily an outcome of the number of females mated with, which was associated with an ensemble of traits including high dominance rank, large body size, relatively voluminous testicles and good body condition. Testes size was significantly larger in sires than in non-sires, but among sires the number of progeny produced was not correlated with testicle size. Sires began the mating season with more body fat than non-sires, but the energetic costs of mating resulted in a 50% reduction in abdominal skinfold thickness during the mating season. We conclude that social status exerts a major impact on paternity by affecting the number of females mated with, that male quality is a critical factor modulating paternity, and that male feeding strategies have a direct influence on variation in male reproductive success.
TL;DR: Data suggest that in cattle the developmental competence of oocytes from small antral follicles is not adversely affected by the presence of a dominant follicle, and there were no differences in the developmental capacity of the oocytes.
Abstract: The aim of these experiments was to determine whether the presence of a dominant follicle affects the developmental competence of oocytes from small antral follicles of cattle. In Expt 1, oocytes or follicular fluid samples were collected from follicles 2-7 mm in diameter before (day 3 of the oestrous cycle; n = 4) or after (days 6 and 7 of the oestrous cycle; n = 6) emergence of the first wave dominant follicle (verified by rectal ultrasonography). Five to ten follicles were aspirated for the determination of individual follicular fluid concentrations of oestradiol, progesterone, testosterone and dimeric inhibin; oocytes from the remaining follicles from each cow were pooled and developmental capacity assessed by in vitro fertilization and maturation. In Expt 2, ovaries containing a young corpus luteum and with or without a large oestrogen-active follicle were collected from the abattoir. Follicular aspirates from small follicles in each pair of ovaries were pooled, and oocyte quality and steroid concentrations were determined. In Expt 1, small follicles obtained before emergence of the dominant follicle contained significantly more oestradiol than they did after emergence (19.5 +/- 1.5 versus 0.7 +/- 1.1 ng ml-1, respectively; P 0.05). In Expt 2, follicular steroid concentrations did not differ in small follicles taken in the presence versus the absence of a large oestrogen-active follicle, and there were no differences in the developmental capacity of the oocytes. There were significant negative correlations between follicular oestradiol concentration and the percentage of blastocysts formed from two-cell (r = -0.90; P < 0.01) and eight-cell embryos (r = -0.65; P < 0.05). These data suggest that in cattle the developmental competence of oocytes from small antral follicles is not adversely affected by the presence of a dominant follicle.
TL;DR: Dual expression and the functional role of Cx43 and Cx45 in cell-to-cell communication in ovarian granulosa cells at various developmental stages were discussed.
Abstract: The expression and localization of gap junction family proteins (connexins) were examined in nonstimulated and gonadotrophin-stimulated ovarian follicles of immature rats. Immunoblot and RNA blot analysis showed the presence of connexin (Cx) 43, Cx40 and Cx45 in ovarian tissue. Of these connexin proteins, Cx43 and Cx45 were identified by immunofluorescent microscopy between granulosa cells in characteristic expression patterns related to follicular developmental stages, while Cx40 was not expressed in granulosa cells but was detected in blood vessels in ovarian stroma. In some plaques of gap junction between granulosa cells, Cx45 was found to be colocalized with Cx43. In immunofluorescent microscopy, the expression of Cx43 was increased with follicular growth, but decreased after induction of ovulation by injection of human chorionic gonadotrophin. In contrast, the Cx45 protein was constantly expressed through follicular development ; however, after ovulation, no staining of Cx45 was detected in the corpus luteum. Dual expression and the functional role of Cx43 and Cx45 in cell-to-cell communication in ovarian granulosa cells at various developmental stages were discussed.
TL;DR: EGF, either alone or with IGF-I, stimulates cumulus expansion; the addition of IGF-i or EGF plus IGF- I significantly enhances nuclear maturation in immature rabbit oocytes; and this effect is mediated by the presence of cumulus cells.
Abstract: The effects of different combinations of epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I) on cumulus expansion and meiotic maturation were examined in rabbit oocytes. Selected rabbit follicular oocytes were matured in vitro and were classified as cumulus\p=n-\oocytecomplexes or denuded oocytes. They were cultured in TCM 199, and were treated with growth factors at different concentrations: EGF at 0, 1, 10, 50 and 100 ng ml \m=-\1, IGF-I at 0, 50, 100 and 200 ng ml \m=-\1 and EGF plus IGF-I at 10 + 50; 10 + 100; 50 + 50 and 50 + 100 ng ml \m=-\1, respectively. After 6 h of culture, the oocytes were assessed for nuclear maturation and after 16 h of culture, for cumulus expansion and maturation stage. After culture for 6 h, the incidence of germinal vesicle breakdown was higher (P < 0.05) in all of the growth factor treatments tested compared with controls. After culture for 16 h, EGF enhanced the incidence of cumulus expansion at all of the concentrations tested. Cumulus expansion was greatest with 50 mg EGF ml\m=-\1 plus 100 ng IGF-I ml\m=-\1 (72.0% versus 2.4% in controls). Treatment with IGF-I significantly increased (P< 0.05) the incidence of metaphase II stage, and maximum stimulation occurred at 100 ng IGF-I ml \m=-\1 (84.5% versus 31.1% in controls). However, IGF-I did not affect cumulus expansion. When denuded oocytes were used, no positive effects on nuclear maturation rates were observed for any treatment. These results suggest that: (1) EGF, either alone or with IGF-I, stimulates cumulus expansion; (2) the addition of IGF-I or EGF plus IGF-I significantly enhances nuclear maturation in immature rabbit oocytes; and (3) this effect is mediated by the presence of cumulus cells.
TL;DR: Results demonstrate the importance of the relationship between exogenous gonadotrophin treatment and onset of anaesthesia for laparoscopic examination and AI in tigers and indicate that ovulation success is high if anaesthesia/laparoscopy is performed after this time, and intrauterine insemination can result in healthy young.
Abstract: The ovarian response to equine chorionic gonadotrophin (eCG) and human chorionic gonadotrophin (hCG), the effect of timing of ovulation relative to hCG injection and the use of laparoscopic intrauterine artificial insemination (AI) were examined in two subspecies of tiger (Panthera tigris). Adult female tigers were subjected to the same eCG/hCG treatment followed by laparoscopy under xylazine/diazapam/ketamine HCl anaesthesia at 39-42 h (Group I, n = 9), 46-49 h (Group II, n = 5) or 51-55 h (Group III, n = 5) after hCG. Six of these females, observed to be postovulatory at the time of laparoscopy (Group II, n = 3; Group III, n = 3), were subjected to intrauterine AI. The number of preovulatory follicles observed on the ovaries of Group I females was twofold greater (P < 0.05) than the number observed on ovaries of females in Group II and III. Fewer (P < 0.05) corpora lutea were observed on ovaries of Group I females (1.3 +/- 0.6) compared with the number of corpora lutea in Group II and III (combined average, 7.8 +/- 0.8 corpora lutea per female). Only one of ten females in Groups II and III failed to ovulate by the time of laparoscopy. Four Group I females never ovulated, based on a laparoscopic re-evaluation 4 weeks later. One female inseminated 46 h after hCG (Group II) became pregnant and delivered a healthy cub after a normal gestation. There were no apparent differences between subspecies in response to the same ovulation induction protocol. Results demonstrate the importance of the relationship between exogenous gonadotrophin treatment and onset of anaesthesia for laparoscopic examination and AI in tigers. Data clearly indicate that anaesthesia/laparoscopy conducted too early (39-42 h after hCG) compromises the number of females and proportion of follicles ovulating. In contrast, ovulation success is high if anaesthesia/laparoscopy is performed after this time, and intrauterine insemination can result in healthy young.