Showing papers in "Reproduction in 1982"

Preservation of hamster oocytes to assay the fertilizing capacity of human spermatozoa.

Abstract: Between 70 and 80% of zona-intact hamster ova survived freezing after slow cooling (approximately 0.3 degrees C/min) to -80 degrees C in Medium PB1 containing 1.5 or 2.0 M-DMSO before transfer to -196 degrees C. After slow warming (approximately 8 degrees C/min), there was no difference in survival if the DMSO was diluted out by a slow stepwise or a rapid single addition of medium. When slow cooling was terminated at -40 degrees C by direct transfer to -196 degrees C, up to 75% of the ova survived rapid warming (approximately 500 degrees C/min) and rapid dilution if the medium contained 2.0 M-DMSO. The survival rates were calculated on the basis of the number of thawed ova which retained their normal morphological appearance after a 1 h incubation before removal of the zona pellucida with trypsin. All of these ova were penetrated after incubation with mouse spermatozoa, indicating that the freezing procedure per se does not adversely affect the penetration of frozen-thawed hamster ova by heterologous spermatozoa. There was no difference in the penetration rate of human spermatozoa into frozen (34%) or fresh (42%) oocytes when a Hepes-buffered Tyrode solution containing 30 mg BSA/ml and 2.0 M-DMSO was used as the freezing medium. However, fewer ova frozen in Medium PB1 containing 4 mg BSA/ml and 2.0 M-DMSO were penetrated by human spermatozoa (18%) compared with freshly collected ova (38%). Zona-free ova did not survive the freezing procedure as well as zona-intact ova. The survival of hamster oocytes stored at -196 degrees C offers a convenient means of supplying and transporting these ova for the assessment of the fertilizing capacity of human and other heterologous spermatozoa.

Effect of delayed insemination on in-vitro fertilization, culture and transfer of human embryos.

Abstract: Oocytes were obtained from patients with tubal infertility at fixed times after the onset of the endogenous LH rise or hCG injection, and were inseminated immediately after recovery or after periods of 4-4 1/2, 5-5 1/2 and 6-6 1/2 h in culture in vitro. Delayed insemination resulted in a marked increase in the proportion of oocytes that were fertilized and developed to normal embryos and maximum rates occurred after 5-5 1/2 h in culture (0-1/2 h, 26%; 4-4 1/2 h, 50%; 5-5 1/2 h, 89%; 6-6 1/2 h, 69%). The range and mean (+/- s.d.) intervals from insemination for the pronuclear and early cleavage stages were 27-43 (35.6 +/- 4.4) h for 2-cell stages, 36-65 (45.7 +/- 8.3) h for 4-cell stages, 45-73 (54.3 +/- 12.6) h for 8-cell stages and 68-85 h for the 16-cell stage. In 7/50 patients receiving 1 or 2 embryos at the 2-, 4- and 8-cell stages, fetal development was normal and 2 women had twin pregnancies (36% success compared with 8% for single embryos). All pregnancies were from the groups in which insemination was delayed for 5-6 1/2 h. It is concluded that a short period of culture in vitro may allow the completion of oocyte maturation, and improve the results of in-vitro fertilization.

Purification and Properties of a Major, Low Molecular Weight Protein Released by the Trophoblast of Sheep Blastocysts at Day 13-21

Abstract: Sheep blastocysts (Day 13-21) incubated in a modified Minimum Essential Medium released proteins into the medium at an approximately linear rate over a 24-h period. Single Day-16 blastocysts converted 2-8% of the radioactivity supplied (100 muCi L-[3H]leucine) into non-dialysable macromolecules which were released into the medium. Two-dimensional polyacrylamide gel electrophoresis revealed that at Day 13 there was only one major product (Protein X), consisting of three closely similar isoelectric species of (pI of denatured polypeptides about 5.5), each with molecular weights of 17 000. Between Days 14 and 21 additional proteins were detected. One of these was of high molecular weight (greater than 660 000) and did not appear on the two-dimensional gels, but Protein X continued to predominate until Day 23 when it could not be detected. Explants of chorion from Day 30 of pregnancy failed to secrete Protein X. Protein X was released in significant quantities (50-100 micrograms per 24 h) by the trophoblast but not the yolk sac of Day-14 and Day-16 conceptuses, but was present in very low amounts in the tissues. Protein X from the incubation medium of Day-14 and Day-16 conceptuses was purified by successive DEAE ion exchange and Sephacryl S-200 gel chromatography. Because Protein X and some of the other proteins are produced transiently between Days 13 and 21, it is possible that they may play a role in maternal recognition of pregnancy in sheep.

Role of striated penile muscles in penile reflexes, copulation, and induction of pregnancy in the rat

Abstract: Summary. In 4 experiments, various striated penile muscles of the rat were excised. Without the ischiocavernosus (IC) muscles no dorsiflexions ('flips') of the glans penis occurred during ex copula reflex tests, but erections were unaffected. In attempted copulation, males lacking the IC muscles rarely gained intromission, apparently because dorsiflexion of the glans penis is necessary for penetration of the vagina. Nonetheless some males lacking the IC muscles displayed the gross motor pattern of intromission and ejaculated, but rarely within the vagina. Males lacking the bulbocavernosus (BC) and levator ani (LA) muscles were incapable of developing intense erections ('cups') in ex copula tests, but they did have lesser erections, probably due to vascular action. Males with excised BC and LA muscles displayed normal copulatory behaviour, including intromission and intravaginal ejaculation, but only 1/15 females mated to these males became pregnant. The infertility of the males was attributed in part to their inability to form the penile cup, which caused them to withdraw a larger portion of the seminal plug from the vagina and, presumably, prevented the plug from being tightly lodged against the cervix. In male rats copulation apparently requires co-ordination of the penile vasculature with the contraction of separate groups of striated penile muscles, each having a distinct contribution to the integrated pattern of copulation and, ultimately, to the male's fertility.

Effect of breast-feeding patterns on human birth intervals

Abstract: This discussion describes the methods which have been used to investigate lactational infertility and examines how different breastfeeding patterns influence human birth intervals. Lactational infertility can be measured in 3 different ways: by the duration of the interbirth interval; by the duration of lactational amenorrhea; and by the return of ovulation. The ultimate test of fertility is pregnancy. Several reports have demonstrated that breastfeeding increases the interval between pregnancies. For example 2 studies compared the time to next conception in nursing and nonnursing mothers from Alaskan Eskimo and rural Indian populations. Despite the wide differences in climate and culture the conception rates were similar in the 2 populations and conception occurred sooner in the nonlactating than lactating mothers. Despite clear evidence that breastfeeding is associated with prolonged interbirth intervals it cannot be assumed that breastfeeding per se is directly responsible for this effect. In many cultures and particularly in Africa sexual taboos are imposed on nursing mothers and reduced frequency of intercourse could explain at least partially the fertility inhibiting effect of breastfeeding. The return of menstruation postpartum has been used in many studies as an indirect index of resumed ovulation. This is a convenient method because it is easy to measure and can be applied to large populations. Many studies have shown that duration of postpartum amenorrhea is longer in breastfeeding than nonnursing mothers. In nonnursing mothers the duration of postpartum amenorrhea averages about 3 months. Among nursing mothers it may last for more than 2 years. Most studies which have attempted to define the timing of ovulation after childbirth have used endometrial biopsy. As an alternative the use of plasma or urinary steroid concentrations provides objective evidence of ovulation and enables a quantitative estimate of menstrual cycle adequacy. The interbirth consists of 3 phases: lactational amenorrhea; the menstrual interval (the interval between the return of postpartum menstruation and next conception); and the length of gestation itself. Only the period of gestation is relatively fixed. Thus it is important to consider the timing and frequency of ovulations during lactational amenorrhea and during the menstruating interval. The combined evidence suggests that the menstruating interval is associated with a reduction of fecundity which is less complete than it is during the phase of lactational amenorrhea. Suckling is a major variable in the control of postpartum ovulation yet relatively few studies have attempted to measure the suckling stimulus. A study of Konner and Worthman (1980) of ]Kung hunter gatherers suggested that very frequent suckling exerts a profound inhibitory effect upon reproduction. The early and regular use of supplementary food will have a detrimental effect on the contraceptive effect of breastfeeding. Malnutrition and age are additional factors that have been suggested as an influence on lactational infertility. For individual mothers breastfeeding cannot be relied upon as a guarantee against pregnancy. Its main importance as a contraceptive method is in developing countries.

Regulation of survival of rat pachytene spermatocytes by lactate supply from Sertoli cells

Abstract: Summary. During incubation of fragments of seminiferous tubules in the absence of glucose, pachytene spermatocytes and round spermatids died within 24 h, while Sertoli cells were still viable. The germ cells survived for at least 72 h in seminiferous tubule fragments which were incubated in the presence of glucose. Lactate rather than glucose is essential for [3H]uridine incorporation and survival of isolated pachytene spermatocytes. However, if the spermatocytes were incubated in the presence of Sertoli cells, glucose maintained the incorporation of [3H]uridine into the germ cells. Sertoli cells secreted lactate in the presence of glucose and the lactate secretion was stimulated 2\p=n-\4-foldby FSH. It is concluded that the activity and survival of pachytene spermatocytes in vitro can be regulated by the supply of lactate from Sertoli cells.

Seasonal variation in LH and testosterone release in rams of two breeds.

Abstract: Blood was collected hourly for 24 h in December, February, April, June and September from Prealpes du sud and Ile-de-France rams. Coincidence of the LH and testosterone peaks was found for 96.4% of a total of 670 LH peaks and 647 testosterone peaks. The number of LH and testosterone peaks increased by 66% in Ile-de-France rams and 200% in Prealpes du Sud rams between December and June (P less than 0.001). Values in June and September were similar in Prealpes du Sud rams. There were no differences between breeds in December, but in June, Prealpes du Sud had significantly more peaks than did Ile-de-France rams (P less than 0.025). The numbers of LH and testosterone peaks increased significantly (P less than 0.05) in Prealpes du Sud rams between December and February or April. These results indicate that, although numbers of peaks of LH and testosterone increase when the animals pass from the non-breeding to the breeding season, the genotype influences the pattern of release through the year.

Effect of progesterone on basal LH and episodic LH and FSH secretion in heifers

Abstract: Heifers between Days 6 and 10 of the cycle were allocated at random to groups of 8 and treated with (i) a 4% progesterone-releasing intravaginal device (PRID) + oestrogen capsule for 12 days; (ii) 4% PRID for 12 days; (iii) 20% PRID for 12 days; (iv) 4% for 14 days; or (v) 20% PRID for 14 days. Blood was obtained daily during treatment and at 2- or 4-h intervals for 72 h after removal of PRIDs. Some animals were sampled every 20 min for 4.676 h on the 3rd day after PRID insertion, and 1 day before and 36 h after removal of the PRID insertion, and 1 day before and 36 h after removal of the PRID. During progesterone treatment there was: (i) no correlation between concentrations of progesterone and LH within days; (ii) a significant negative correlation between progesterone and days (P less than 0.01) and also between progesterone and LH over days (P less than 0.01); (iii) the overall correlation co-efficient between LH and days was positive (P less than 0.05). The amplitude of LH or FSH episodes was not affected as progesterone concentrations declined during PRID treatment, but the number of LH (but not FSH) episodes was increased (p less than 0.01). After PRID removal, the amplitude of both LH and FSH episodes increased (P less than 0.01). We suggest that progesterone is part of a negative feedback complex on LH secretion in cattle and that this effect is apparently mediated through frequency of episodic LH release.

Evidence for direct inhibition of ovarian function by prolactin

Abstract: There is no doubt that in breast-feeding women, suckling with its associated hyperprolactinaemia prevents the resumption of ovarian activity for prolonged periods (see McNeilly, 1979) The extent of this suppression varies greatly among species but in all for which there are adequate data it appears to depend critically upon the intensity of the suckling stimulus (Lamming, 1978) Our recent data from women show that in the pattern of suckling, frequency and duration, throughout the day, are both key factors in maintaining the elevation of basal levels of prolactin associated with lactation (McNeilly, Howie & Houston, 1980a; Howie & McNeilly, 1982) Suckling also releases large quantities of prolactin, maintaining a physiological hyperprolactinaemic state which is directly associated with the duration of lactational amenorrhoea (Delvoye, Badawi, Demaegd & Robyn, 1978; Duchen & McNeilly, 1980) The question remains, how does suckling suppress ovarian activity? The levels of prolactin in blood during peak lactation appear to be many times the requirement for production of milk It therefore becomes pertinent to ask whether this prolactin is released solely to stimulate milk production or whether it is involved directly in the suppression of ovarian activity If there is a direct involvement then there are two loci for this action; an effect at the hypothalamic-pituitary level or a direct effect on the ovary While the former has received some attention (see McNeilly, 1979, 1980a), relatively little information is available (for species other than the rat) on whether or how prolactin might act on the ovary and, in particular, how high levels might interfere or block follicular development during lactation (McNeilly, 1980b) The purpose of this paper is to review the evidence for a direct action of prolactin on the ovary in the context of the effects of prolactin in the control of normal ovarian cyclicity

Neuroendocrine control of milk ejection

Abstract: The mammary glands of mammals from the platypus to man are identical in fine structure, and consist of alveolar tissue within which milk is continuously secreted during lactation. An alveolar structure increases enormously (perhaps by 10 000-fold) the surface area for secretion relative to the external size of the gland, but at the same time complicates the problem of milk removal. Small ducts generate substantial surface tension forces that oppose the movement of fluids: suction is therefore a relatively ineffective method for removal of alveolar milk. The problem has been overcome by investing the alveoli in a basket-like reticulum of myoepithelium which contracts in response to oxytocin released from the posterior pituitary. When stimulated by oxytocin the alveoli are compressed and milk is expelled into the larger collecting ducts for removal by the sucking of the young. Further, the establishment of a nervous link between the nipple and the oxytocinergic neurones of the hypothalamus allows milk ejection from the alveolar tissue to be co-ordinated with the sucking of the young. Thus is formed the most classical of neuroendocrine reflexes. Our analysis of this reflex would, if we adopted a traditional approach, commence with the sensory input to the hypothalamus (afferent limb) and conclude with a study of the motor response, i.e. the release of oxytocin and milk ejection (efferent limb). There are however sound reasons for reversing this procedure. The process of milk ejection is remarkably uniform in all mammals, but the same cannot be said of the afferent limb of the reflex arc. Two of the laboratory animals make a good comparison in this respect (Text-fig. 1).

Response of seasonally anoestrous ewes to small-dose multiple injections of Gn-RH with and without progesterone pretreatment.

Abstract: Four groups, each of 5 seasonally anoestrous ewes, were treated i.v with small doses (75, 125, 250 or 500 ng) of Gn-RH at 2-h intervals for 48 h. A further 15 ewes received 14 days pretreatment with progesterone and then the 250 ng Gn-RH treatment. Gn-RH injections induced an episodic pattern of LH secretion which differed significantly for the doses of Gn-RH used. A preovulatory LH surge occurred in all but 1 of the ewes during the period of Gn-RH treatment. Ovulation occurred in all 15 ewes pretreated with progesterone and in 19/20 ewes treated with Gn-RH alone. Although normal luteal function occurred in all ewes pretreated with progesterone, it was present in only 5 of the 20 ewes treated with Gn-RH alone. Oestrus, as shown by mating, occurred at a mean time of 34.7 +/- 2.6 h after the start of Gn-RH treatment only in those ewes receiving progesterone pretreatment. These results indicate that progesterone pretreatment has a marked effect on the ability of small doses of Gn-RH to induce ovulation and normal luteal function in seasonally anoestrous ewes.

Inhibition of ovulation and LH secretion in the gilt after treatment with ACTH or hydrocortisone

Abstract: Treatment with ACTH (100 i.u.) or hydrocortisone acetate (250 mg) twice daily for 12 days to increase cortisol concentrations blocked ovulation in all gilts. The preovulatory surge of LH was also blocked in the treated gilts. Oestrous cycle length and number of days in oestrus were similar for all treatments except that in one of the 2 experiments ACTH suppressed oestrus in 4 of the 5 gilts treated.

The human menstrual cycle: plasma concentrations of prolactin, LH, FSH, oestradiol and progesterone in conceiving and non-conceiving women

Abstract: Hormonal profiles were obtained throughout 26 conception cycles and 27 non-conception control cycles. The pregnancies followed treatment (clomiphene or bromocriptine) in 12 women but were spontaneous in the remaining 14. No sustained significant difference between the various types of conception cycle was found for LH, FSH, oestradiol or progesterone concentrations. Prolactin concentrations varied widely, suggesting that mean cycle prolactin concentrations ranging from 45 to 760 mi.u./l are compatible with conception. Although there were no significant differences in progesterone secretion within the conception cycles, there were highly significant differences between the conception cycles and the non-pregnant control cycles. Mean progesterone concentrations in the conception group were higher (P less than 0.005) than those in the control women over Days 3-8 following the LH peak. This difference could only be partly accounted for by heterogeneity within the control group (15-20% of the control cycles had low progesterone concentrations and were probably subfertile. It is suggested that the higher conception cycle progesterone concentrations during the early part of the luteal phase may constitute a preimplantation component of the maternal recognition of pregnancy in women.

The induction of ovulation and luteal function in seasonally anoestrous ewes treated with small-dose multiple injections of Gn-RH

Abstract: Seasonally anoestrous ewes were injected i.v. with 250, 500 or 1000 ng Gn-RH at 2-h intervals for 8 days (2 sheep/treatment). Each injection of 250 or 500 ng Gn-RH resulted in a transient rise in plasma LH concentrations. Treatment with 1000 ng Gn-RH per injection resulted in a more sustained rise in plasma LH concentrations in 1 of 2 sheep during the early part of the treatment period. A preovulatory-type LH peak occurred 17-48 h after the start of treatment in all ewes, with a second preovulatory-type peak 106-133 h later in those ewes receiving 500 or 1000 ng Gn-RH per injection. Ovulation, with subsequent normal luteal function, occurred in all sheep. However, the rise in plasma progesterone concentrations appeared to be delayed in those ewes treated with 500 or 1000 ng Gn-RH compared to ewes treated with 250 ng Gn-RH. These data suggest that the absence of ovulation during seasonal anoestrus is due to an inadequate pattern of episodic LH secretion.

Effects of epinephrine and hypotaurine on in-vitro fertilization in the golden hamster

Abstract: Using an experimental design in which the addition of hypotaurine or epinephrine was staggered through time, evidence was found that suggests these two compounds are working independently and sequentially to stimulate the fertilizing capacity of hamster spermatozoa in vitro. Prior exposure of spermatozoa to hypotaurine is a prerequisite for the action of epinephrine in causing activation and penetration of hamster ova. A definite role for hypotaurine in inducing capacitation of hamster spermatozoa is also demonstrated. The alpha-adrenergic antagonist, phentolamine, was more effective in blocking fertilization of hamster ova in vitro than was propranolol, a beta-antagonist. This indicates tha catecholamines may be working by way of alpha-adrenergic receptors in causing capacitation of hamster spermatozoa. The failure to block fertilization with phentolamine after epinephrine has exerted its effect implies that epinephrine acts in a hormone-like fashion.

Development and cellular localization of rat testicular aromatase activity

Abstract: Summary. Oestradiol secretion by isolated Leydig cells, Sertoli cells, myoid cells, germinal cells and liver cells from rats of different ages was measured by a validated radioimmunoassay technique. All cells, except germinal cells and liver cells, produced oestradiol when incubated in the presence of testosterone. Sertoli cells from 7- and 10-day-old rats and from prenatally irradiated adult rats were 7 times more active than cell preparations from 15\p=n-\50-day-oldrats. The oestradiol production in Sertoli cells prepared from 7\p=n-\25-day-oldrats could be stimulated with FSH. Oestradiol production by isolated Leydig cells from mature animals was 3\p=n-\4times greater than that with preparations from immature animals. LH had no effect on oestradiol production, but testosterone production was stimulated more than 5-fold. The oestradiol production by the isolated cells was affected by culture time, the presence of fetal calf serum in the culture medium and incubation temperature. During a culture period of 6 days oestradiol production by immature Sertoli cells increased more than 5-fold and that by Leydig cells decreased to about 10%. Oestradiol levels in testes from 10\p=n-\50-day-oldrats were approximately 20% of those in testes from 7-day-old animals.

Uterine blood flow and uterine arterial, venous and luminal concentrations of oestrogens on days 11, 13 and 15 after oestrus in pregnant and non-pregnant sows.

Abstract: Summary. Concentrations of oestradiol-17\g=b\and oestrone were measured in the uterine arterial and venous blood of anaesthetized sows on Days 11, 13 or 15 of the oestrous cycle or of pregnancy. Uterine arterial blood flow and the amounts of oestradiol-17\g=b\and oestrone in uterine flushings were determined in the same animals. In pregnant animals arterial and venous concentrations were significantly different (P < 0\m=.\05)for oestradiol-17\g=b\on Days 11 and 13 and for oestrone on Day 15. Uterine content of both steroids was consistently greater in pregnant than in non-pregnant animals with a peak on Day 13. Uterine arterial blood flow increased from Day 11 to 13 of pregnancy then declined (P < 0\m=.\08)by Day 15; no change in uterine blood flow occurred on the corresponding days of the oestrous cycle.

Role of the vomeronasal organ and prolactin in the acceleration of puberty in female mice.

Abstract: Young female mice were grouped on Day 21 after birth and subjected to removal of the vomeronasal organ. Soiled bedding from intact adult males failed to advance the onset of first oestrus in these lesioned mice compared to the various control groups. Vomeronasal organ lesions of prepubertal females also prevented increases in uterine weight following exposure to soiled bedding for 48 h on Day 23 when compared to controls. Lowering prolactin by injections of bromocriptine for 48 h on Day 26, but not Day 23, advanced the onset of puberty in intact and vomeronasal organ-lesioned females. Elevating prolactin by injections of domperidone were without effect on the early onset of oestrus when compared to sham-injected controls. It is concluded that marked similarities exist in both the receptor system and neuroendocrine mechanism of male pheromone action observed in prepubertal females and that seen in the adult.

Production, transport, maturation, storage and survival of spermatozoa in the male Japanese quail, Coturnix coturnix

Abstract: Male Japanese quail have relatively large testes (2.26% of body weight), a rapid rate of spermatogenesis (14.4-15.8 days) and an efficient production of spermatozoa (92.5 x 10(6)/g testis per day). The daily output of spermatozoa is high (308 x 10(6) per bird, 2.08 x 10(6) per g body weight). The total number of extragonadal spermatozoa was 308 x 22 x 10(6) per bird. Spermatozoa were transported through the genital ducts in about 1 day, maturing quickly in the epididymal region and stored briefly in the ductus deferens. Spermatozoa isolated in the ductus deferens by ligatures around the duct rapidly lost the capacity for motility after 3 days. It is concluded that, compared to mammals such as the rat, the reproductive strategy of the quail involves the rapid production, maturation and transport of spermatozoa through the reproductive tract, in association with a limited capacity to store spermatozoa for long periods within the male genital ducts.

Maintenance of ATP concentrations in and of fertilizing ability of fowl and turkey spermatozoa in vitro.

Abstract: Summary. Fowl and turkey spermatozoa, when diluted in a glutamate-based medium and incubated at 40\s=deg\Cunder aerobic conditions showed a similar rate of oxygen utilization and maintained similar cellular ATP concentrations. Under anaerobic conditions, the glycolytic metabolism of fowl spermatozoa was sufficient to maintain a high ATP concentration, whilst turkey spermatozoa had a much lower glycolytic ability and their ATP levels fell rapidly. The maintenance of high sperm ATP concentrations was directly related to subsequent fertilizing ability of the spermatozoa. Diluted fowl semen showed good fertilizing ability ( > 70%) under aerobic conditions and under anaerobic conditions in the presence of 10 mM-glucose, but diluted turkey semen maintained good fertilizing ability only under aerobic conditions.

Morphological selection of human spermatozoa in vivo and in vitro

Abstract: Light microscopic assessment of human spermatozoa in post-coital samples of cervical mucus revealed a significant improvement in the general sperm morphology between the semen and the cervix. Further analysis showed that the excluded spermatozoa were more likely to be those with midpiece or tail defects that impaired motility. Significant changes were also found when the morphology of spermatozoa recovered from the uterus and Fallopian tubes following AIH was compared with the semen used for insemination: in the semen, uterus and oviducts there were respectively 53, 77 and 71% spermatozoa with completely normal morphology, and 12, 3 and 0.6% spermatozoa with defects of the midpiece and/or tail (as assessed by surface replica electron microscopy). Selection of spermatozoa in vitro by allowing them to swim upwards through a nickel mesh also reduced the number of spermatozoa with abnormal morphology, particularly of the midpiece and tail. It is concluded that the apparent selection of morphologically normal spermatozoa is not a direct function of the female tract, but that the spermatozoa can effect their own selection because of their differential motility.

Preovulatory follicular development in sheep treated with PMSG and/or prostaglandin

Abstract: The patterns of growth and atresia of antral follicles including that of the presumptive preovulatory follicle were examined in sheep ovaries for a 24\\p=n-\\48-h period after the induction of luteolysis with a prostaglandin analogue, cloprostenol or cloprostenol + PMSG. Ewes were ovariectomized at various times after the initiation of the treatments. All follicles \\m=ge\\1mm in diameter were dissected from the excised ovaries and the antral fluid and granulosa cells recovered. Individual follicles were classified as healthy or atretic on the basis of the number of granulosa cells recovered and then subclassified as to whether they contained intrafollicular levels of oestradiol that were \\m=ge\\or < than 100 ng/ml. In another series of similarly treated ewes, the ovarian secretion rates of oestradiol and the intrafollicular concentrations of oestradiol in all large antral follicles (\\m=ge\\5mm diameter) as well as the levels of progesterone in peripheral plasma were measured at different times after induction of luteolysis. The results showed that a large 'oestrogenic' follicle (\\m=ge\\5mm diameter and secreting \\m=ge\\1ng oestradiol/min) appears around 10 h after the cloprostenol injection and that this presumptive preovulatory follicle emerges before the corpus luteum has ceased to function. Moreover, the presumptive preovulatory ('oestrogenic') follicle appears to develop from the pool of small 'oestrogenic' follicles (1\\p=n-\\3mm diameter) after the onset of luteolysis. The emergence of a large 'oestrogenic' follicle is accompanied by a widespread increase in atresia (> 80%) in all other classes of antral follicles (\\m=ge\\1mm in diameter). During the first 10 h of cloprostenol-induced luteolysis, PMSG (a) prevented the normal occurrence of atresia in the large follicle population; (b) enhanced oestrogen secretion in a greater proportion of large antral follicles compared to that in control animals; (c) temporarily 'rescued' and/or prevented small antral follicles (1\\p=n-\\4mm diameter) from undergoing atresia; but (d) had little, or no, effect on the overall population of antral follicles (\\m=ge\\1mm diameter). After 24 h, the atresia-preventing effects of PMSG were no longer discernible and the only obvious difference noted, compared to the controls, was the number of large oestrogen-secreting follicles.

p-Aminobenzamidine, an acrosin inhibitor, inhibits mouse sperm penetration of the zona pellucida but not the acrosome reaction.

Abstract: Summary. The effect of p-aminobenzamidine (pAB), an inhibitor of mouse sperm acrosin, on mouse sperm capacitation, motility, acrosome loss and fertility in vitro was examined using zona-intact and zona-free eggs. With intact eggs, concentrations of pAB ranging from 0\m=.\1 to 1\m=.\0mM in the sperm preincubation medium effectively inhibited fertilization (13\p=n-\0%,respectively), but these same suspensions (106 cells/ml) showed high rates of fertilization with zona-free eggs (100\p=n-\95\m=.\3%);with the lower concentration of 105 cells/ml, fertilization rates of zona-free eggs decreased with increasing concentrations of pAB (100\p=n-\55%).Washing of treated samples gave fertilization rates similar to control samples (87\m=.\1and 84\m=.\6%,respectively), indicating that inhibition was reversible and that there had been no interference with the capacitation process. Whiplash motility was also observed in all samples, suggesting that the apparent inability to penetrate the zona might be due to an acrosomal defect. This was confirmed by electron microscopic examination of treated sperm samples. In high concentrations of pAB, many cells had undergone the acrosome reaction, i.e. membrane vesiculation, but acrosomal matrix dispersal was inhibited. These results are consistent, therefore, with a role for the acrosomal enzyme acrosin in matrix dispersal, but not the acrosome reaction itself, and in penetration of the zona pellucida.

Comparative ultrastructure of hatched human, mouse and bovine blastocysts.

Abstract: A hatched human blastocyst obtained after in-vitro fertilization and culture was examined by transmission electron microscopy and the ultrastructural features compared with hatched mouse and bovine blastocysts. The human blastocyst contained a continuous layer of trophoblast cells with apical junctional complexes, an inner cell mass and the beginning of a primitive endoderm layer. Certain ultrastructural features were common to the blastocysts of all 3 species; these included characteristic junction regions between adjacent trophoblast cells, an abundance of microvilli on the external surfaces of the blastocysts and the presence of well developed mitochondria and numerous ribosomes in the trophoblast cells. The features that were dissimilar included the extent of development of the endoderm layer, the appearance of the inner cell mass and the nature and extent of vesicular inclusions in the trophoblast cells.

Plasma concentrations of prolactin, progesterone, relaxin and oestradiol-17β in sows treated with progesterone, bromocriptine or indomethacin during late pregnancy

Abstract: Pregnant gilts (3/group) were given no treatment, 10 mg bromocriptine twice daily by mouth, from Day 111 of pregnancy to 1 day post partum, 25 mg progesterone s.c. at 6-h intervals from Days 111 to 116 inclusive or 400 mg indomethacin by mouth at 6-h intervals from Day 111 to 116 inclusive. Before spontaneous delivery maternal plasma prolactin and relaxin concentrations started to rise almost simultaneously between 58 and 47 h before the first piglet and both hormones reached peak values when the plasma progesterone concentration had started to decline rapidly (approximately 21-23 h). Suppression of prolactin levels by bromocriptine prevented the onset of lactation completely but had no obvious influence on changes of the other hormone concentrations and the course of parturition. Progesterone treatment delayed the onset of expulsion of the piglets but did not delay the simultaneous increase in prolactin and relaxin concentrations. These changes in hormone levels were prevented by indomethacin treatment but occurred essentially unchanged when the treatment was ended. The results support the concept that parturition in the pig is preceded by a biphasic increase of plasma prostaglandin levels.

Sperm transport in the human female reproductive tract in relation to semen analysis characteristics and time of ovulation.

Abstract: Laparoscopic sperm recovery from the pouch of Douglas and tubal fimbriae was performed in 64 infertile couples. Spermatozoa were recovered from 16/35 couples investigated after AIH, and from 13/29 couples post coitum. The method of insemination had no effect on the result, which was positive in 45.3% of all couples, although AIH did result in significantly larger numbers of peritoneal spermatozoa. The number of peritoneal spermatozoa did not show any direct correlation with the number inseminated, but there were reductions along the tract of 5.83 (+/- 1.4 s.d.) orders of magnitude for total sperm count, and 5.52 (+/- 1.21 s.d.) for the number of motile spermatozoa. Only sperm motility had a significant influence on the success of sperm transport; spermatozoa were recovered from patients with sperm densities as low as 3.0 and 3.5 x 10(6)/ml, but with 56 and 44% motile spermatozoa. No influence of cycle day within the range +/- 4 days of ovulation on sperm transport was found. In 45 couples, routine semen analyses were apparently completely normal, but the incidence of sperm recovery was still only 49% (22/45), suggesting that a failure of sperm transport may have been a significant causative factor in their infertility.