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Showing papers in "Biology of Reproduction in 1979"


Journal ArticleDOI
TL;DR: The results suggest that continuous exposure to medium levels of estrogens, particularly in the presence of sustained low progesterone secretion, may alter pituitary secretion of prolactin in aging rats.
Abstract: Longitudinal studies were performed in a colony of aging female rats,from 4-33 months of age,to determine the chronologicalchange inreproductive patterns and the changes in sex steroid, prolactin and gonadotropin secretionassociatedwith different reproductive states. The present study demonstrates that the incidence (65%) of irregular estrous cycles in aging rats increased abruptly from 10-12 months of age. Subsequently, female rats became chronically anovulatory with persistentvaginalcornificationsand theirovariescontained developed follicles but no corpora lutea. The highest incidence (65%) of constant estrous (CE) rats occurred at the age of about 19 months. During the anovulatory state, CE rats displayed low to medium levels of serum estradiol, estrone, testosterone and androstenedione, low levels of progesterone and minimal levels of 20nhydroxyprogesterone. Preovulatory increasesin gonadotropin and prolactin release,similar to those seen in young cycling ratson proestrus,were not observed in CE rats.Whereas serum basal LH levels remained unaltered, morning FSH levelswere increased in CE rats.The lattermay account for the persistent follicular development in aging rats during chronic anovulatory state. Serum basal prolactin levels were normal in CE rats during the early phase (11-16 months of age) of the anovulatory state, but were subsequently increased 3 to 4-fold beyond 24 months of age. Moreover, ovariectomy at a young age prevented the increased pituitary prolactin release in old female rats. These results suggest that continuous exposure to medium levels of estrogens, particularly in the presence of sustained low progesterone secretion, may alter pituitary secretion of prolactin in aging rats. With further advance of age and following many months of anovulatory function, aging female rats exhibited ovulatory activity at irregular intervals. After each ovulation, formed corpora lutea were maintained for a prolonged period, presumably due in part to the existing high prolactin levels in the circulation of older female rats. These corpora lutea in old “pseudopregnant (PSP)” rats were functional as indicated by active secretion of progestins, with 20a-hydroxyprogesterone levels greater than those of progesterone in the circulation. These results indicate that the ovaries of aging rats retain their functional capacity to develop follicles and corpora lutea and to secrete steroid hormones. Although the cause(s) responsible for cessation of normal ovulatory cycles in aging female rats is unknown, the present study demonstrates that the chronic anovulatory state in aging female rats is characterized by significantly reduced ovarian secretion and the lack of cyclic increases in pituitary gonadotropin and prolactmn release. The causal relationships between the decreased ovarian steroid production and the absence of preovulatory surges of gonadotropin release in aging CE rats remain to be determined.

396 citations


Journal ArticleDOI
TL;DR: The data have led us to conclude that the 5 day cycle is due to a prolonged progesterone secretion during the metestrous and diestrous stages of the cycle.
Abstract: The present study was undertaken to characterize hormonal and morphological events in 4 day and 5 day rat cycles, in order to test 3 different theories concerning the etiological factors altering follicular phase length in mammals. Three rats were killed at each 2 h interval throughout each cycle type. In addition to organ weight measurements, serum levels of estradiol, progesterone, 20ohydroxypreg-4-en-3-one, LH, FSH and prolactin were assessedin terminal samples. The beginning of uterine intraluminal fluid accumulation coincided with the decline in progesterone levels seen during diestrus, rather than with the rise in estrogen and was delayed 12 h in the 5 day cycle from the time of last estrus. The retention of this fluid during the evening of proestrus was 6 h longer in the 4 day cycling rat. Ovulation occurred earlier in the 5 day cycling rats than in those with a 4 day cycle. No significant differences in the gonadotropins or 2oo-hydroxypreg-4-en-3-one were seen when comparing the 2 types of cycles. Estradiol rose during the night of diestrus I (the same time in the cycle) and was identical in both cycle types. Progesterone was not released on proestrus prior to the LH surge in either type of cycle. However, we did find that progesterone values were higher for a longer period of time throughout diestrus I in 5 day cycles. These data have led us to conclude that the 5 day cycle is due to a prolonged progesterone secretion during the metestrous and diestrous stages of the cycle.

287 citations



Journal ArticleDOI
TL;DR: It is suggested that the cellular source for P is the granulosa cell and the source for T and E is the theca cell, and a 2 celltype model for synthesis of these 2 steroids is proposed.
Abstract: The follicularcomponents responsible for the synthesisof progesterone (P),testosterone(T) and estrogen (E) have been identifiedby studying in vitro the steroidogenicpattern of theca or granulosa cellsincubated alone with or without ovine FSH, ovine LH, P or T or incubated together with or without ovine LH. Granulosa cells,but not theca cells,isolatedfrom 3 largestpreovulatory and postovulatory folliclesproduced more P in response to the addition of exogenous gonadotropins. Among the 4 different types of folliclesstudied,this response of granulosa cellsisolatedfrom the largest follicle(F1), the one destined to ovulate next, was the greatest.Both theca and granulosa cells isolatedfrom preovulatory folliclesproduced 2-3 times more T when incubated in the presence of gonadotropins. Only theca cellsfrom the second (F2) and third(F3) largestfollicles synthesize more E when incubated with gonadotropins. The response of F3 was greater than that of F2. Addition of T to the incubation system elicitedE synthesisby theca cellsof F3 or F3, but not by granulosa cells of any sizefollicles. Again, the response of theca cellsfrom F3 was greaterthan that of F2. Furthermore, the abilityof theca cellsof F3, isolatedat or shortly afterthe preovulatory in vivo LH surge,to aromatize T to E was significantlylower than that isolatedseveralhours before the LH surge. Combination of the 2 follicular cell types from F3 decreased P, but increased T (9- to 17-fold increase) and E synthesis. Theca cells incubated with exogenous P produced large amounts ofT. We concluded that the cellular source for P is the granulosa cell and the source for T and E is the theca cell.Theca cellsalone cannot synthesizeT or E unless the precursor, P or T, respectively, is added. Both theca and granulosa cellsare required for synthesisof T, followed by E. Thus, a 2 celltype model for synthesisof these 2 steroidsisproposed. The present study alsosuggeststhat the steroidogenic potentialof the follicularcellschanges during the process of follicularmaturation.

191 citations


Journal ArticleDOI
TL;DR: It is concluded that the initial segments of the rat epididymis require high intraluminal concentrations of androgen bound to androgen binding protein.
Abstract: This investigation was undertaken to explore further the dependence of the initial segments of the epididymis upon substances in the testicular fluid. The experimental groups consisted of rats castrated, rats with ligated ductuli efferentes and sham operated controls. The epdidymides were examined by light and electron microscopy 3 and 6 weeks postoperatively. The initial segments of the duct in both ligated and castrated animals exhibited 1) striking decrease in duct diameter and epithelial height, 2) a marked decrease in endoplasmic reticulum in the apical cytoplasm, 3) evidence of diminished activity of the Golgi complex, but 4) persistence of fluid uptake by pinocytosis. Daily administration of 500 pg testosterone proprionate beginning on the first postoperative day maintained the accessory gland weights at normal or supranormal values, but was ineffective in preventing the cytological regression of the initial segments of the caput epididymidis. In an effort to achieve levels of androgen in the blood comparable to those normally found in the rete testis fluid, castrated and ligated rats were implanted s.c. with 30 cm of Silastic tubing containing testosterone, each estimated to release 4 mg/day (Berndtson et al., 1974). Plasma testosterone levels when the rats were killed were 8-10 times normal. Despite these high levels of circulating androgen, cytological dedifferentiation of the initial segments was not prevented. More distal segments of the duct were essentially normal in dimensions and appearance. It is concluded that the initial segments of the rat epididymis require high intraluminal concentrations of androgen bound to androgen binding protein. The possibility that they are dependent upon some other, as yet unidentified, constituent of testicular fluid is not ruled out.

173 citations


Journal ArticleDOI
TL;DR: The pattern of blood flow to uteri of the sows during early pregnancy was similar to that observed during the previous estrous cycle until Day 11 after mating, when UBF increased 3-fold to 4-fold and increased dramatically to Day 30.
Abstract: Uterine blood flow (UBF) of 6 sows was monitored throughout an estrous cycle and the first 30 days of pregnancy using electromagnetic blood flow probes. Probes were placed around both uterine arteries of each sow on Day 12, 13 or 14 of the estrous cycle (first day of estrus = Day 0). The UBF (mI/mm) was recorded twice daily for 15 mm at 0700 and 1600 h. Values were averaged over both 15 mm periods on each day for each artery and considered an estimate of UBF. Blood flow to uteri of nonpregnant sows was highest from Day -5 to estrus and this was followed by a gradual decline during the remainder of the estrous cycle. The pattern of blood flow to uteri of the sows during early pregnancy was similar to that observed during the previous estrous cycle until Day 11 after mating. On Days 12 and 13 of pregnancy, UBF increased (P<0.0l) 3-fold to 4-fold. No corresponding increase in UBF was observed in nonpregnant sows during this 2 day period. By Day 14 of pregnancy, UBF had returned to a level slightly higher than that observed on Day 11, remained relatively constant from Day 14 to 19, then increased (P<0.O1) dramatically to Day 30. A second study was conducted using 7 sows made unilaterally pregnant on Day 2 postmsting (first day of mating = Day 0). Fertilized ova were flushed from one oviduct and the ipsilateral uterine horn was ligated at the uterine body with silk sutures (nongravid horn). Blood flow probes were placed around both uterine arteries and UBF was recorded twice daily. Sows were slaughtered on Day 16 postmating. Five of the 7 sows had embryos and/or embryonic tissue in the nonligated uterine horn (gravid horn) at slaughter. Sows in which embryonic tissue was found had higher (P<0.05) blood flow to the gravid compared with the nongravid uterine horn on Days 12 and 13 of pregnancy. Corpora lutes on the ovary ipsilateral to a gravid uterine horn had higher (P<0.05) progesterone concentrations (± SEM) than did corpora lutes on the contralateral ovary (5.45 ± 1.69 vs 2.07 ± 0.49 Mg/g luteal tissue).

162 citations


Journal ArticleDOI
TL;DR: Follicular function was estimated by radioimmunoassay of estradiol-1 713in jugular vein plasma of female cats by identifying the earliest sign of follicular activity and Vaginal epithelial changes were characterized as follows.
Abstract: Follicular function was estimated by radioimmunoassay of estradiol-1 713in jugular vein plasma of female cats. The mean base level of estradiol-1 713in plasma was 11.7 pg/mI (SD = 4.8; n = 106). The follicular phase, defined as the time interval when estradiol-17j3 levels were >20 pg/mI plasma, was 7.4 days (SD = 2.3; n = 108), range 3-16 days. The duration of follicular function was not affected by the occurrence of coitus or ovulation. Estradiol-1713 fell from peak levels to <20 pg/mb plasma within a mean of 2.6 days (SD = 1.1; n = 105). The interval between follicular phases was 8.1 days (SD = 3.1; n = 41), ranging from 3-15 days. Proestrus was not observed with regularity and was seen in only 27/168 cycles, averaging 1.2 days (SD = 0.8). Duration of estrous behavior without regard for coitus was 7.4 days (SD = 3.7; n = 168; range 2-19 days). Duration of estrus in cats that experienced coitus and ovulation was 8.6 days (SD = 4.1; n = 32), in those that had coital contact but failed to ovulate, it was 8.3 days (SD = 4.3; n = 43), but in those without coital contact, it was 6.2 days (SD = 2.9; n 93) (coitus vs no coitus, P<0.01). Estrous behavior was seen in 8, 36, 52, 80 and 85% of cats on follicular phase Days 1-5, respectively. All cats were in estrus by follicular phase Day 6. The interval between estrous periods was 9.0 days (SD 7.6; n = 162; range 4-22 days) if ovulation did not occur. Ovulation and the subsequent pseudopregnancy prolonged return to estrus for 45.0 days (SD = 10.3; n = 32). No conspicuous changes in size and appearance of external genitalia were observed. Clearing of the vaginal smear (absence of noncellular debris) was the earliest sign of follicular activity. Vaginal epithelial changes were characterized as follows: Anuclear cells (fully cornified) increased from %5% to “40% of total cell population and intermediate cells (partially comified with intact nucleus) decreased from �45% to 6% progressively from the first to the fourth day of the follicular phase; parabasal cells (noncornified), generally low throughout a cycle (1-6%), were absent on follicular phase Days 4-7 and the following day; superficial cells (partially cornified with signs of degeneration of the nucleus) did not change much during the cycle (range, 40-50%) except for a slight increase during the follicular phase (range, 50-60%).

155 citations


Journal ArticleDOI
TL;DR: Depending on the doses, the combinations of testosterone and estradiol-17j3 resulted in 2 types of interaction: at low doses, these 2 steroids acted synergistically to decrease testicular content of spermatids and spermatozoa and testicular weights but had little or no effect on serum testosterone andEstradiol1713 or weights of sex accessory tissues; at higher doses, there was an apparent direct antagonism between these 2 compounds on all tissue components measured.
Abstract: The effects of subcutaneous sustained-release implants of testosterone and estradiol-173, given either alone or in combination to adult male rats, on the weights of testis and sex accessory tissues, the testicular content of spermatids and spermatozoa and the serum concentrations of testosterone, estradiol-17a and gonadotropins were investigated. Increasing amounts of testosterone, in the absence of added estradiol, caused a biphasic response (decline followed by a partial recovery) in testicular weight and in the number of spermatids and spermatozoa/testis. Serum testosterone initially remained unchanged and subsequently rose. lhis pattern was reflected by the weights of sex accessory tissues. Before serum testosterone rose, serum LH decreased to undetectable levels. Serum estradiol-17a levels were not affected by increasing doses of testosterone. Low doses of estradiol-17a (0.1 cm and 0.3 cm implants), in the absence of added testosterone, had no significant effect on serum estradiol-17a levels, on testicular weights or on the testicular content of spermatids and spermatozoa, but did cause a fall in serum LH and testosterone levels and in the weights of sex accessory tissues. Higher doses of estradiol-17i3 resulted in increased serum estradiol1713 levels and either a decrease or a sustained low level for all other measured parameters (weights of testes and sex accessory tissues and testicular content of spermatozoa and spermatids). Depending on the doses, the combinations of testosterone and estradiol-17j3 resulted in 2 types of interaction: 1) at low doses, these 2 steroids acted synergistically to decrease testicular content of spermatids and spermatozoa and testicular weights but had little or no effect on serum testosterone and estradiol-1713 or weights of sex accessory tissues; 2) at higher doses, there was an apparent direct antagonism between these 2 compounds on all tissue components measured.

153 citations







Journal ArticleDOI
TL;DR: Pretreatment of ovaries with EGTA and hypertonic sucrose appears to be a reliable procedure for improving the yield of monodisperse, viable, biochemically intact granulosa cells for use in in vitro examinations of follicular physiology and function.
Abstract: Chemical treatments previously shown to disrupt gap junctions were applied to rat ovaries with antral follicles prior to expressing the granulosa cells with a blunt spatula. Exposure of the ovaries to 6.8 mM EGTA lethyleneglycol-bis-13-aminoethyl ether)-N,N’-tetracetic acid I and 0.5 M sucrose either by perfusion in situ or incubation in vitro generated monodisperse suspensions of granulosa cells with improved integrity as evaluated by several criteria. Similar numbers of granulosa cells (7-8 X 106 per ovary) were obtained either by direct physical expression or by pretreatment of the ovaries followed by physical expression. However, the ability of the granulosa cells to exdude trypan blue dye was consistently improved 2-3-fold by pretreatment with EGTA and hypertonic sucrose (from 25% to 40-80%). Likewise, in vitro synthetic capacities for protein, RNA and DNA were enhanced 2-6-fold, 5-10-fold and 10-20-fold, respectively. A qualitative one-to-one correspondence between protein synthesis and vital dye exdusion was demonstrable but the quantitative relationship between dye exclusion and macromolecular precursor incorporation appeared to be nonlinear. Cells obtained using the chemical pretreatments also demonstrated better survival in minimal medium for at least the first 12 h of culture The enhancements observed could not be obtained by reversing the order of the chemical treatments or by treating granulosa cells after physical removal from ovarian follicles. Pretreatment of ovaries with EGTA and hypertonic sucrose appears to be a reliable procedure for improving the yield of monodisperse, viable, biochemically intact granulosa cells for use in in vitro examinations of follicular physiology and function.


Journal ArticleDOI
TL;DR: The results are consistent with the proposal that in association with degeneration of the germ cells of the cryptorchid testis, the structure and function of the Sertoli cells are acutely sensitive to the raised intra-abdominal temperature.
Abstract: Within 7 days of the surgical induction of cryptorchidism, the Sertoli cells demonstrated an accumulation of lipid inclusions and dilatations of smooth endoplasmic reticulum Aggregations of large vacuoles were observed at the basal aspects of the Sertoli cells and appeared to arise from local dilatations of the intercellular spaces between opposing inter-Sertoli cell junctions These modifications of the inter-Sertoli cell junctional complexes disappeared as the cryptorchid state persisted, though some observations suggest that the associated membranes form complexly arranged bodies The function of the Sertoli cells was altered in the cryptorchid testis as demonstrated by severe reduction in androgen binding protein (ABP) production by the 4 week cryptorchid testis and the lack of measureable ASP within the caput epididymidis Serum FSH and LI-I levels became significantly elevated within 14 days of establishing cryptorchidism, suggesting diminished feedback from the damaged testis Continuation of cryptorchidism was associated with progressive widening and folding of the peritubular tissue of the seminiferous tubule leading to bizarre arrangements of the tunics propria The results are consistent with the proposal that in association with degeneration of the germ cells of the cryptorchid testis, the structure and function of the Sertoli cells are acutely sensitive to the raised intra-abdominal temperature

Journal ArticleDOI
TL;DR: There was a seasonal pattern of LH and FSH in ovariectomized mares and the LH levels increased approximately 2 months earlier in the light-treated group than in the control group, and the rise in LH in the OVX groups occurred at approximately the same time as the onset of the ovulatory season in the intact groups.
Abstract: A study was done of the influence of length of photoperiod (control vs 16 h fixed photoperiod) and season (month) On: 1) changes in concentrations of plasma gonadotropins in ovariectomized (OVX) mares and 2) changes in plasma concentrations of gonadotropins and diameters of ovarian follicles preceding the onset of the ovulatory season in ovarian intact mares. In ovarian intact groups, intervals from start of project (January 6) to the first day of the ovulatory estrus, first appearance of a 30 mm follicle and onset of the ovulatory season (first ovulation) were shorter for the light-treated than for the control group. The changes in gonadotropmn concentrations and follicular development preceding the onset of the ovulatory season (Day 0 = day of first ovulation) were not significantly different between light-treated and control groups. Mean plasma FSH levels fluctuated between Day -60 and Day -20 and then declined reaching a significant drop by Day -8. Mean plasma LH levels remained low until Day -8 and then increased reaching a maximum on the last day examined. The mean number of follicles 15-25 mm appeared to increase gradually from Day -60 to Day -20, remained elevated between Day -20 and Day -8 and then declined rapidly to a minimum on Day -1. The mean diameter of the largest follicle appeared to increase gradually from Day -60 to Day -8 and then increased rapidly between Day -8 and Day -1. The decline in FSH appeared to precede the decline in number of follicles 15-25 mm and the rise in LH. The rise in LH was temporally associated with the final growth and maturation of the preovulatory follicle. The ovulatory LH profile at the onset of the ovulatory season was similar in shape but lower in magnitude than the ovulatory LH profile during the middle of the ovulatory season. Removal of the ovaries during the anovulatory season did not evoke a postovariectomy rise in gonadotropin levels. However, there was a seasonal pattern of LH and FSH in ovariectomized mares and the LH levels increased approximately 2 months earlier in the light-treated group than in the control group. The rise in LH in the OVX groups occurred at approximately the same time as the onset of the ovulatory season in the intact groups.

Journal ArticleDOI
TL;DR: It is concluded that in the presence of low and unchanging LH and FSH concentrations from metestrus to proestrus large antral follicles become more responsive to LH.
Abstract: The LH and FSH receptor content in thecal and granulosa cells of large antral follicles was measured by in vitro binding assays and in vivo autoradiography during the rat estrous cycle. Specific binding of l’25I]-hCG to granulosa cells increased from <1000 cpm/llg DNA on estrus, metestrus and diestrus to 6000 CPM/Mg DNA on proestrus. Specific binding of l’2511-hFSH to granulosa cells was consistently between 2000 and 3000 cpm/ g DNA throughout the cycle. Specific hCG binding to thecal cells also increased between diestrus and proestrus, while specific hFSH binding to thecal cells was essentially nondetectable. The increase in LH receptors in large antral follicles from diestrus to proestrus could be correlated with an increased ability of these follicles to produce cyclic AMP and estradiol during in vitro incubations with increasing concentrations (0.06-60 pg/mI) of 0LH. Incubation of antral follicles collected on metestrus, diestrus and proestrus with and without testosterone revealed a progressive increase in both follicular aromatase activity and endogenous androgen production. It is concluded that in the presence of low and unchanging LH and FSH concentrations from metestrus to proestrus large antral follicles become more responsive to LH. This responsiveness is associated with an increase in LH receptors both in thecal and granulosa cells and increased production of estradiol. Although the hormonal stimulus for the increase in granulosa cell LH receptor on proestrus is not known, it is suggested that increased follicular estradiol might play a pivotal role.


Journal ArticleDOI
TL;DR: The data suggest that prolonged sexual receptivity in this species is supported in the presence of declining estrogen and continuously rising progesterone concentrations, and a preovulatory estradiol-17(3 surge exists and is likely responsible for triggering LH release.
Abstract: Serum estrone, estradiol-1 7!) and progesterone were measured in bitches in which LH, sexual behavior and laparoscopically confirmed time of ovulation had been previously studied. Steroid values from 25 estrous periods were normalized to day of peak LH (Day 0). Estrone, estradiol-17(3 and progesterone concentration did not differ significantly in either dogs subjected to laparoscopy at 48 h intervals or those bitches undergoing no laparoscopy. During the preovulatory interval, mean peripheral estrone concentrations were more variable than estradiol-1713; however, both estrogens tended to rise gradually throughout this time period. Overall maximal estradiol-1 713 concentration was detected on Day -2 with estrone peaking later (Day -0.5). Both estrogens declined (P<0.05) coincidentally with the LH surge. Progesterone from Days -14.0 through -1.5 was maintained at basal concentrations. An increase (P<0.05) in mean progesterone occurred on the day of the preovulatory LI-I peak which correlated with direct observation of apparent preovulatory follicle luteinization. Progesterone increased gradually from Day -0.5 through 8 and then varied for the remainder of the sampling period. Analysis of individual cycles indicated that circulating serum concentrations of reproductive steroids fluctuated from day to day or within days of the proestrous-estrous interval. In dogs subjected to laparoscopy, initial evidence of the presence of visible preovulatory follicles was closely related to the first detectable elevations in both estrone and estradiol-1 713. Either estrone or estradiol-1 713 concentrations or both surged sharply in 24 of the 25 cycles examined; however, only titers of estradiol-17j3 were elevated above baseline in all cycles prior to, or at the time of, the LH peak. In 16 of 25 cycles, estradiol-1713 concentrations declined by 20 pg/mI or more 12-24 h prior to the onset of sexual receptivity. Bitches remained in estrus during periods of declining estrone and estradiol-1 713and increasing progesterone levels. These data integrate the hormonal, ovarian and behavioral events of the estrous cycle of the bitch and suggest that: 1) a preovulatory estradiol-17(3 surge exists and is likely responsible for triggering LH release; 2) estrone may play a supportive role to estradiol-1713 in the endocrine control of LH secretion; 3) preovulatory changes in follicular morphology are distinct and can be correlated with a shift from estrone and estradiol-17f3 to progesterone secretion; 4) prolonged sexual receptivity in this species is supported in the presence of declining estrogen and continuously rising progesterone concentrations.


Journal ArticleDOI
TL;DR: Data indicate that the capacity of endometrial tissue to secrete PGF20 is increased during early pregnancy, and lends support to the hypothesis that PGE2 may be the factor responsible for maintenance of the estrous cycle.
Abstract: To determine if the synthesis and/or secretion of prostaglandins PGF20 and PGE2 differed during the late luteal phase of the cycle and early pregnancy, a combination of in vivo and in vitro parameters were studied. Synthesis of PGF20 and PGE2 by ovine endometrial tissue in vitro was studied on Days 13, 15 and 17 of the estrous cycle and pregnancy. The prostaglandins were quantified by radioimmunoassay. There was no difference in the quantity of PGF20 synthesized by tissue collected on Day 13 of either the cycle or pregnancy. Synthesis of PG F20 was greater on Day 15 (P<0.01) and tended to be greater on Day 17 (P<0.10) of pregnancy than on Day 15 or 17 of the estrous cycle. Synthesis of PGE2 was also significantlygreateron Days 15 (P<.O01) and 17(P<0.05) of pregnancy than on the same days of the estrous cycle. Synthesis rates of both PGs in vitro tended to decrease from Days 13-17 in tissue collected from cycling ewes, while increasing from Days 13-15, then falling again on Day 17 of pregnancy. Concentrations of PGF20 and PGE2 in endometrial tissue followed the same pattern as in vitro secretion, suggesting that in vitro secretion accurately reflects the in vivo capacity of endometrial tissue to synthesize PGs. Concentrations of PGF20 in uteroovarian venous serum were greater on Day 13 (P<0.05) and not different on Days 15 and 17 of pregnancy compared with the same days of the estrous cycle. However, concentrations of PGE2 in uteroovarian venous serum were greater on Days 15 (P<0.01) and 17 (P<0.05) of pregnancy than on the same days of the estrous cycle. Prostaglandin F20 was present in uterine flushings in extremely small quantities (0.3-0.6 ng/ml) and PGE2 was nondetectable (<10 pg/mi) on Days 13, 15 and 17 of the estrous cycle. In contrast, concentrations of PGF20 and PGE2 were relatively high on all days of pregnancy examined and on Day 15 were at least 50 times greater than on Day 15 of the estrous cycle. These data indicate that the capacity of endometrial tissue to secrete PGF20 is increased during early pregnancy. The fmding that PGE2 is also secreted at a greater rate during early pregnancy lends support to the hypothesis that PGE2 may be the factor responsible for maintenance of the

Journal ArticleDOI
TL;DR: It is concluded that macroscopic assessment of follicular atresia in ovarian follicular populations is directly related to follicular diameter.
Abstract: The binding of [125 Il-labeled human follicle stimulating hormone ([12511 -FSH) and chorionic gonadotropin ((12111 -hCG) to intact ovine follicles was studied in vitro as a function of follicular diameter and stage of morphological atresia. Histological confirmation of the atretic classification was established and the incidence of atresia in those follicles studied was variable and directly related to follicular diameter (P<0.0i). The binding of [‘251)-hFSH and (‘251)-hCG to theca was relatively constant when compared to the change in granulosa binding that was associated with increased follicular diameter or stage of atresia. When studied without regard to the stage of atresia, the binding of (12511 -hFSH to granulosa cells decreased and that of [12511 -hCG increased with increased follicular diameter. These changes were thought to reflect changes in the relative incidence of atresia within each size group rather than decreased binding per se. Subsequent analysis of [12511 -labeled gonadotropin binding to granuhosa cells as a function of both folhicular diameter and stage of atresia simultaneously indicated that the extent of (‘2511-hFSH binding was determined solely by stage of atresia rather than follicular diameter (P<0.05). Conversely, while 152511 -hCG binding was decreased by increased atresia, the overall extent of binding was determined by follicular diameter (P<0.01). It is concluded that macroscopic assessment of follicular atresia in ovarian follicular populations is directly related to follicular diameter. In addition, the ability of granulosa cells to bind (12511. labeled gonadotropins in vitro varies as a function of follicular diameter and stage of atresia.

Journal ArticleDOI
TL;DR: It is concluded that it is the hormonal environment of the endometrium at the time of surgery which primarily governs the quantity and quality of the proteins by short term cultured explants.
Abstract: Explants of endometrium from the porcine uterus secrete labeled proteins into the growth medium when incubated in vitro in modified Eagle’s MEM4 containing radioactive L-leucine. Tissue from 60 day pregnant animals secrete about 30 times as much radioactive material into the medium in 24 h as explants taken from nonpregnant animals on Day 3 of the estrous cycle. The secretions by tissue from pregnant animals were also qualitatively distinct and contained appreciable quantities of 2 basic proteins, lysozyme and a uterine-specific phosphatase. The latter was identical to an iron-containing purple protein previously purified either from uterine secretions of progesterone treated, nonpregnant animals or from allantoic fluid. This protein is believed to be involved in iron transport from mother to fetus. Explants from the endometrium of animals on Days 30, 45, 60, 75, 90 and 105 of pregnancy showed considerable differences in their capacities to produce the purple protein. Production was maximal by Day 60 tissue (2 mg/g tissue/24 h), but very low in tissue from late pregnancy (Day 105), an observation which may have considerable implication with regard to dietary iron supplementation of the pregnant sow. Neither the presence of progesterone nor estradiol-17a in the incubation medium altered the quantity or quality of the proteins produced by the explants during the 24 h incubation. We conclude that it is the hormonal environment of the endometrium at the time of surgery which primarily governs the quantity and quality of the proteins by short term cultured explants.

Journal ArticleDOI
TL;DR: Results suggest that prostaglandins, probably of the E series, may be the mediators of the increased endometrial vascular permeability which results from the application of an artificial stimulus to the sensitized rat uterus.
Abstract: The role of prostaglandins in mediating the increased endometrial vascular permeability which results from the application of an artificial stimulus to the uterus of the rat sensitized for the decidual cell reaction was investigated. Immature rats were pretreated so that at the time of application of the artificial stimulus, the unilateral injection into the uterine lumen of 50 �.il phosphate buffered saline containing gelatin, their uteri were sensitized for the decidual cell reaction. Endometrial vascular permeability was quantified with �2 2 51l-labelled bovine serum albumin ([12 �Il BSA); the ratio of the concentrations pf radioactivity in the injected to noninjected uterine horns 15 mm after an iv. injection of [121 Il-BSA was used as an index of the effect of the stimulus on endometrial vascular permeability. Indomethacin, an inhibitor of prostaglandin biosynthesis, significantly reduced the endometrial vascular permeability indices of rats killed 4 or 8 h after the intraluminal treatment. Compared to the noninjected horn, the concentrations of prostaglandins of both the E and F series were markedly elevated within 15 mm in the injected uterine horn and remained elevated for at least 2 h. When injected into the uterine lumen of rats treated with indomethacin to inhibit endogenous prostaglandin production, prostaglandin E2, but not prostaglandin F20, increased the endometrial vascular permeability index. When given together into the uterine lumen, prostaglandin F20 inhibited the stimulatory effect of prostaglandin E2 on the endometrial vascular permeability index. These results suggest that prostaglandins, probably of the E series, may be the mediators of the increased endometrial vascular permeability which results from the application of an artificial stimulus to the sensitized rat uterus.

Journal ArticleDOI
TL;DR: The results substantiate a hypothesis that the presumed single gene mutation, diabetes, acts through a CNS anomaly to cause infertility, as it also may act to cause obesity and thermoregulatory disturbances.
Abstract: Mice that are homozygous for the autosomal recessive mutation diabetes (db) fail to reproduce. We have established that the hypoplastic vaginal epithelia, uteri and ovaries can respond comparably to control tissues on hormonal stimulation. Gonadotropin release from the pituitary gland appeared to be depressed in female mutant mice, but responded normally to exogenous gonadotropin releasing hormone (GNRH) in both sexes. Immature mutant females failed to ovulate on PMS stimulation. Hypothalamic GNRH content was greater than normal in the adult female mutant mice (<0.001), suggesting that in the females, at least, GNRH release may be inadequate, with secondary blunting of pituitary function. The db males appeared to have comparable to normal LH, FSH and GNRH levels and little sign of reproductive tract atrophy. Only the preputial glands were significantly reduced from normal size. The db males did fail to show mating behavior. The results substantiate a hypothesis that the presumed single gene mutation, diabetes, acts through a CNS anomaly to cause infertility, as it also may act to cause obesity and thermoregulatory disturbances.

Journal ArticleDOI
TL;DR: Cumulus maturation is induced by the ovulatory surge of LH, and small differences were attributed to differences in circulating levels of gonadotropin as a function of time.
Abstract: The temporal relationship between maturational events in the cumulus oophorus and the oocyte of adult rats was examined. The time of preovulatory surge of Lii was estimated from analysis of the critical period. Cyclic rats were killed on the afternoon and night of proestrus; hCGtreated rats were injected during the early morning hours of proestrus and were killed up to 13 h later. At necropsy, the ovaries were removed and the oocytes with their cumuli were isolated from the large preovulatory follicles. The intercellular mucification and tissue dissociation characteristic of cumuli around ovulated oocytes began to appear 4.24 ± 0.15 h after endogenous LH secretion or 4.31 ± 0.25 h after hCG. Transformation of the cumulus started at its periphery and spread centripetally. By 5.70 ± 0.21 and 7.17 ± 0.34 h, respectively, the cumuli had completed their differentiation. Maturation of the oocytes began before and ended after maturation of the cumuli. Timing of the maturational events preceding spontaneous cyclic ovulation and hCG-induced ovulation was similar. Small differences were attributed to differences in circulating levels of gonadotropin as a function of time. It was concluded that cumulus maturation is induced by the ovulatory surge of LH.

Journal ArticleDOI
TL;DR: It is suggested that collection of rete fluid from laboratory animals without recourse to efferent duct ligation may provide a more physiologic preparation for study of the fluid environment for testicular spermatozoa.
Abstract: A method has been developed for collection of rete testis fluid from a rat efferent duct without prior efferent duct ligation. Flow rates averaged 0.64 ± 0.04 SD mI/mm. Pressure in the unligated efferent duct ranged from 1.8-4.5 cm H20. After 14 h of ligation, duct pressure reached 40 cm 1120. Emptying of the rete contents after 16-29 h of efferent duct ligation was biphasic with 30-40% of accumulated fluid draining within 40 mm and a further 20-40% imerging at a much slower rate over the next 4 h. Recovery of more than 60% of theoretical fluid stored within 5 h was rare. Sperm counts from 2 rats with unligated efferent ducts yielded sperm production rates of 28.2 and 34.4 X 10’ sperm/day. After 16-29 h efferent duct ligation sperm concentrations were highest in the initial drainage and fell by 3 1-78% during the early fast drainage phase. Testosterone concentration averaged 24.2 ± 4.0 SD and 20.0 ± 3.5 SD ng/ml for rats without and with efferent duct ligation respectively with no significant difference between the two groups. Testosterone concentration remained constant in successive volume increments of rete fluid after 16 h efferent duct ligation. When sufficient rete fluid volume was available for detection, concentrations of estradiol-17i3 averaged 248 ± 95 pg/mI in unligated rats and 68 ± 42 pg/mI in ligated rats (P<0.05). Additionally, estradiol-17a levels increased more than 5-fold during 3 h drainage of rete fluid after 23 h efferent duct ligation suggesting that estradiol secretion may be suppressed by efferent duct ligation. These studies suggest that collection of rete fluid from laboratory animals without recourse to efferent duct ligation may provide a more physiologic preparation for study of the fluid environment for testicular spermatozoa.

Journal ArticleDOI
TL;DR: It appears that domestication results in increased reproductive potential through earlier initiation of nesting and by delay of the termination of reproduction until later in the summer; and a decrease in the synchronization of the hormonal events supporting reproduction between the male and female of a pair.
Abstract: Comparisons between “wild” and “game farm” mallards (Anas platyrhynchos) were made to assess the differences in the temporal changes of plasma hormones. Seasonal variation in the levels of immunoreactive luteinizing hormone (LH), testosterone, 5cs-dihydrotestosterone (DHT), estrone, estradiol-1 7 3 and progesterone were measured in male and female mallards. In all birds there was a vernal increase in the concentrations of LH and testosterone in plasma which were correlated with the development of the testes and ovaries prior to and during the nesting season. The concentrations of estrogens in the plasma of the females were, in general, slightly higher during the nesting season but were much lower than the levels of testosterone. The highest levels of LH and testosterone in the females coincided precisely with the period of egg laying which occurred approximately one month earlier in game farm females than in wild females. The concentrations of LH and testosterone in the plasma of females decreased rapidly during incubation. In wild males, the decline in levels of these hormones temporally coincided with that of females. In contrast, plasma levels of LH and testosterone of males of the game farm stock remained elevated after the beginning of incubation in females to which they were paired. On the basis of these results and an examination of the literature, it appears that domestication results in: 1) increased reproductive potential through earlier initiation of nesting and by delay of the termination of reproduction until later in the summer; and 2) a decrease in the synchronization of the hormonal events supporting reproduction between the male and female of a pair. Testicular weights and plasma levels of testosterone become higher in game farm and domestic males than in the wild stock but levels of LH are similar.

Journal ArticleDOI
TL;DR: Data of this study strongly suggest that the postovulatory follicle of hens, which does not morphologically develop into a corpus luteum, should be considered as an active endocrine tissue.
Abstract: An in vitro incubation system has been developed to study the steroidogenic capability of the theca or granulosa cells in the postovulatory and 3 largest preovulatory follicles of chickens. Follicles were collected at different times during the hen’s 26 h laying cycle taking into consideration the endogenous plasma LU peak(s). Three major sex steroids, progesterone (P), estrogen (E) and testosterone (T), produced by these follicular cells were measured by radioimmunoassay. Granulosa cells isolated from pre- or postovulatory follicles spontaneously synthesized large amounts of P and little T. In contrast, theca cells collected from the same follicles did not produce any sex steroids. The influence of endogenous gonadotropins on steroidogenesis of these follicular cells incubated in vitro was seen only in the P synthesis I)y granulosa cells of the largest preovulatory follicles: P synthesizing ability was significantly greater in follicles collected at the time of preovulatory LH surge than those collected at any other times studied. Interestingly, granulosa cells of smaller (more immature) follicles, in general, showed greater ability to synthesize P and T than did the first largest which is destined to ovulate next. These findings provide direct evidence that granulosa cells of both pre- and postovulatory follicles are steroidogenically active and spontaneously synthesize P and T. In contrast, the role of theca cells in follicular steroidogenesis remained unclear. Data of this study also strongly suggest that the postovulatory follicle of hens, which does not morphologically develop into a corpus luteum, should be considered as an active endocrine tissue.