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R. B. L. GWATKIN and D. T. WILLIAMS

Summary.

Before fertilization, the protease present within the cortical granules of the hamster egg is relatively stable to heat. Once discharged into the medium, however, it is extremely heat sensitive, undergoing inactivation even at 37°C. Thus, body temperature would be expected to prevent the zona reaction of one egg from rendering neighbouring eggs infertile.

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R. B. L. Gwatkin and D. T. Williams

Summary. Capacitated golden hamster spermatozoa bound to the inner as well as to the outer surface of the zona pellucida, suggesting that the receptor-for-spermatozoa may occur throughout this egg envelope. When solutions of hamster zonae pellucidae were prepared by heating zonae in an aqueous buffer, receptor activity was retained and was stable to boiling. The addition of such solutions to capacitated spermatozoa (5 zonae/μl) prevented them from binding to eggs and fertilizing them. Solubilized mouse zonae were also partly effective, as would be predicted from the limited cross-binding binding between mouse and hamster gametes. Receptor activity was lost following the zona reaction.

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R. B. L. Gwatkin, G. H. Rasmusson and D. T. Williams

Summary.

Fusion of capacitated spermatozoa with the vitelline membrane, but not actual penetration, appears to initiate the cortical reaction in hamster eggs. The reaction can be artificially induced by the application of positively charged particles to the vitelline surface, a situation which may normally be prevented by the zona pellucida. Exposure of hamster eggs to neuraminidase, to lectins (concanavalin A and phytohaemagglutinin-P), to a monovalent ionophore (boromycin) and to 1,3-bis(4chlorocinnamylideneamino)guanidine elicits a cortical granule discharge resulting in a block to fertilization. These agents all appear to act by inducing depolarization of the vitelline membrane.

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R. B. L. GWATKIN, O. F. ANDERSEN and D. T. WILLIAMS

Summary.

Capacitation of mouse spermatozoa in vitro is brought about by epididymal secretions released into the medium at the time of sperm collection. Inhibition by glucaro(1→4)lactone indicates that an essential component of these secretions is β-glucuronidase. In the absence of the secretions, capacitation can be induced by components of the cumulus oophorus.

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H O Goyal, T D Braden, C S Williams and J W Williams

In this review, we report permanent dysmorphogenesis of the penis and loss of fertility in adult rats treated neonatally with estrogen. Specifically, we report replacement of smooth muscle cells and cavernous spaces by fat cells in the corpus cavernosum penis, but not in the adjoining corpus spongiosum. Induction of these novel, region-specific phenotypes is dose-dependent, requires a critical window of exposure and associated with decreased testosterone and up-regulation of estrogen receptor α (ERα). The resistance of ERα knockout mice to develop these abnormalities implies an unequivocal role for ERα in mediating maldevelopment of the penis. Additionally, the prevention of estrogen-inducible penile abnormalities by ER antagonist ICI 182 780 implies that a functional ER-mediated pathway is essential for inducing penile abnormalities. Likewise, the ability of testosterone or dihydrotestosterone to negate these abnormalities suggests a role for an androgen receptor (AR)-mediated pathway. Taken together, these observations led us to hypothesize that neonatal estrogen exposure, via an ER-mediated pathway (direct action) or an AR-mediated pathway (indirect action through decreased testosterone) or both pathways, up-regulates ERα expression in stromal cells of the penis, which are then reprogrammed such that their differentiation into smooth muscle cells is inhibited and their differentiation into adipocytes is stimulated.

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E. D. Williams, B. J. Major, T. J. Martin, J. M. Moseley and D. D. Leaver

Parathyroid hormone-related protein (PTHrP) was detected at 32.8 ± 3.9 pmol l−1 in uterine luminal fluid from immature rats treated with oestradiol. As mRNA encoding PTHrP has previously been localized to implantation sites in pregnant rats, the role of luminal PTHrP during pregnancy was explored. Infusion of a parathyroid hormone (PTH)/PTHrP receptor antagonist, [Asn10,Leu11]PTHrP(7–34) amide, into the uterine lumen during pregnancy in rats resulted in excessive decidualization. This effect was also observed after intrauterine infusion of a monoclonal antibody raised against PTHrP. The effect of infusion of PTH/PTHrP receptor antagonist was dependent upon successful implantation, was dose-dependent and confined to the treated horn. A decrease in the number of apoptotic decidual cells in antagonist-infused uterine horns compared with vehicle or non-infused horns was detected immunohistochemically at day 13 of pregnancy, and this decrease is likely to contribute to the 'over-decidualization' observed. In pseudopregnant rats, infusion of PTH/PTHrP receptor antagonist into the uterine lumen resulted in an increase in uterine wet weight of the infused horn compared with the non-infused horn, indicating a direct effect on deciduoma formation. Thus, activation of the PTH/PTHrP receptor by locally produced PTHrP appears to be crucial for normal decidualization during pregnancy in rats.

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E. D. Williams, D. D. Leaver, J. A. Danks, J. M. Moseley and T. J. Martin

The effect of parathyroid hormone-related protein (PTHrP) on the contractility of uterine segments taken from pregnant rats and the localization of PTHrP in the uterus during pregnancy were investigated. PTHrP(1-34) had a potent inhibitory effect on spontaneous contractions of the longitudinal layer of uterine myometrium taken from rats at day 4 of pregnancy (IC50 1.6 nmol l−1). In low calcium De Jalon's solution, it also decreased baseline tension IC50 1.5 nmol l−1) in a concentration-dependent manner. The effect of PTHrP(1-34) on uterine motility decreased as pregnancy progressed until day 13, after which PTHrP(1-34) had no measurable effect on uterine contractility. In contrast, PTHrP(1-34) had no effect on the contractions of the circular smooth muscle of the uterus at any stage of pregnancy. PTHrP(50-69) had no effect on the contractility of either muscle layer of the myometrium. A temporal pattern of staining for PTHrP in the uterus of pregnant rats was observed, and the changes in the staining patterns in the endometrium and myometrium were different in each layer. These data suggest that PTHrP may have at least two distinct roles in the uterus, a relaxing action on longitudinal muscle that depends on the hormonal state of the rat and a novel effect either intraluminally or within the endometrial layer.

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T. D. Williams, A. Dawson, T. J. Nicholls and A. R. Goldsmith

Summary. Castration of juvenile and photorefractory adult starlings caused no immediate increase in circulating concentrations of LH. In castrated juveniles and adults exposed to natural changes in daylength, plasma LH increased between mid-October and mid-November, although the increase was more rapid in adults. In castrated photorefractory adults, plasma LH increased 3–5 weeks after transfer to artificial short days (8L:16D). In castrated juvenile starlings plasma LH increased 4–6 weeks after transfer to 8L:16D, irrespective of the age of the birds. Birds as young as 17 weeks had high LH concentrations. These results suggest that the reproductive system of juvenile starlings is in the same state as that of photorefractory adults, and therefore that activation of the hypothalamo–pituitary axis for the first time in juveniles is analagous to the termination of photorefractoriness in adults.

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R. B. L. GWATKIN, D. T. WILLIAMS, J. F. HARTMANN and M. KNIAZUK

Summary.

The cortical granules of hamster ova were ruptured in vitro by electrical stimulation (standard treatment was 150 V, 1·0 msec). Approximately 8 min were required for the cortical granule material so released to induce a complete zona reaction. The active material from the cortical granules was released into the medium from vitelli and was shown to act directly on the zona pellucida and on mouse, as well as on hamster, ova, i.e. its action is not species specific. The action of the cortical granule material was reversed by trypsin inhibitors. Such a tryspin-like protease, causing the zona reaction, was also released from vitelli by spermatozoa.

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L. J. D. ZANEVELD, R. T. ROBERTSON, M. KESSLER and W. L. WILLIAMS

Summary.

Treatment of capacitated rabbit spermatozoa with pancreatic trypsin inhibitor or partially purified seminal plasma trypsin inhibitor and subsequent insemination of such spermatozoa into the oviducts of ovulated rabbits markedly inhibited fertilization. Washing the spermatozoa to remove excess inhibitor did not affect the antifertility action of pancreatic trypsin inhibitor. Seminal plasma trypsin inhibitor was purified by specific binding to a trypsin-maleic anhydride-ethylene copolymer and Sephadex G-25 and G-50 column chromatography. A 500-fold purification was obtained.