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G. Munoz de Vera, B. Marquant-Le Guienne, M. De Almeida and G. A. Voisin

Summary. In vitro, binding of acrosome-reacted spermatozoa to the zona pellucida of mature guinea-pig oocytes was inhibited by guinea-pig sperm anti-T IgG and antibodies. Anti-P IgG antibodies prevented oocyte penetration without interfering with spermzona binding. The fusion of acrosome-reacted spermatozoa with zona-free oocytes was prevented by anti-T IgG and it was diminished by anti-P IgG. In the same conditions anti-S antibodies had no effect in these in-vitro fertilization events. Immunization of female guinea-pigs with P antigen resulted in a significant decrease of the number of tubal cleaved eggs. T antigens were less clearly implicated in fertilization in vivo. This study provides evidence that well characterized autoantigenic molecules of guinea-pig spermatozoa are involved in fertilization events.

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D. F. M. van de Wiel, S. Bar-Ami, A. Tsafriri and F. H. de Jong

Summary. Oocyte maturation inhibitor (OMI), inhibin, progesterone and oestradiol-17β concentrations were measured in fluid collected from small ( < 3 mm), medium size (3–6 mm) and large ( > 6 mm) porcine ovarian follicles, which were obtained on Days 5, 10, 15 and 18 of the oestrous cycle and at 24 h after the onset of oestrus. Concentrations of OMI decreased with increasing follicle diameter (P < 0·05), independent of the stage of the oestrous cycle. Concentrations of inhibin showed a tendency to decrease with increasing follicle diameter on Days 10, 15 and 18, but not on Day 5 of the cycle. Concentrations of OMI and inhibin in the largest follicles were low before the onset of oestrus, and were essentially unaltered 24 h later. A positive correlation was found between OMI and inhibin concentrations, whereas the correlation between inhibin concentration and log (progesterone concentrations) was negative.

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M. A. de las Heras and R. S. Calandra

Summary. Ornithine decarboxylase (ODC) activity was measured in epididymides of 45-day-old rats. Higher ODC activity was detected in the corpus and cauda than in the caput epididymidis. Bilateral castration for 7 days caused epididymal ODC to fall to undetectable values, whereas testosterone restored activity to normal values. The effect of the androgen was significantly inhibited by cyproterone acetate. The caput was more sensitive to the action of testosterone than were the corpus and caudal segments. Unilateral castration for 4 or 8 days did not affect ODC on the control or castrated side, but the activity fell in epididymides of both sides after removal of the remaining testis. These results show that epididymal ODC activity is androgen-dependent.

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G. P. Risbridger, G. Jenkin and D. M. de Kretser

Summary. Rat testicular interstitial fluid and hydroxycholesterol both stimulated testosterone production by isolated Leydig cells in vitro in a dose-dependent manner, but the dose—response lines were not parallel. The addition of cycloheximide blocked the stimulation by interstitial fluid but not that of hydroxycholesterol. Use of the compounds SU 10603 and cyanoketone (which inhibit 3β-hydroxysteroid dehydrogenase and 17α-hydroxylase respectively) or aminoglutethimide (which acts on the cholesterol side-chain cleavage enzyme) showed that the stimulatory factor(s) in interstitial fluid stimulated steroidogenesis at the cholesterol side-chain cleavage enzyme, before the conversion of pregnenolone. This enzyme is rate-limiting in the synthesis of testosterone by Leydig cells and a site of action of LH; therefore, these results support the view that an interstitial fluid factor may be involved in the paracrine regulation of testicular steroidogenesis.

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C. Monet-Kuntz, Marie-Thérèse Hochereau-de Reviers and M. Terqui

Summary. Changes in testicular androgen receptor numbers were studied in lambs from 25 to 100 days of age. During this period, cytoplasmic receptors increased from 5 to 80 pmol/testis and nuclear receptors from 1 to 12 pmol/testis, while the total volume of Leydig cells increased 7-fold. The total number of Sertoli cells doubled between 25 and 40 days of age. From 40 days onward their number remained constant while their cellular and nuclear sizes increased by a factor of 3 and 1·5 respectively. Cytoplasmic receptor concentration was positively correlated with the number of Sertoli cells per section of seminiferous tubule, and negatively correlated with the number of germinal cells per cross section. One explanation for these results could be that Sertoli cells are the main androgen target cells in lamb seminiferous tubules.

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B. Jégou, A. O. Laws and D. M. de Kretser

Summary. Cryptorchidism for 28 or 10 days resulted in a severe disruption of spermatogenesis (assessed histologically or by fertility tests), Sertoli cell function (assessed by seminiferous tubule fluid production after efferent duct ligation, ABP levels, binding of 125I-labelled FSH to testis homogenates and serum FSH levels) and Leydig cell function (assessed by serum LH and testosterone levels, in-vitro testosterone production, binding of 125I-labelled hCG). Orchidopexy after 28 days of cryptorchidism resulted in a poor recovery of spermatogenesis since the majority of tubules were lined by Sertoli cells and a few spermatogonia. No recovery occurred in the indicators of Sertoli and Leydig cell function.

Orchidopexy after 10 days of cryptorchidism also resulted in a poor recovery of spermatogenesis, with a few animals showing partial recovery after 6 months. No recovery occurred in seminiferous tubule fluid production but partial recovery occurred in ABP content and production rate. Serum FSH, LH levels and in-vitro testosterone production by the testis remained elevated and did not change from the values found during cryptorchidism.

Fertility testing at 6 months revealed a small number of rats in which fertility was restored although the number of embryos was lower than in controls. In this group of animals there was a significant improvement in a number of indicators of Sertoli cell and Leydig cell function. These data provide further evidence to link the changes in Sertoli cell and Leydig cell function to the germ cell complement present in the testis.

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M. T. Hochereau-de Reviers, C. Perreau and G. A. Lincoln

Summary. Seasonal changes in the Leydig, Sertoli and stem cells (undifferentiated A0 and cyclic A1) spermatogonia and the daily spermatid production were analysed in the testes of adult Soay rams exposed to short days (8L: 16D) or long days (16L: 8D) for 12 weeks. The total numbers of Leydig, Sertoli and stem cells (A0 + A1) were not affected by the treatments, but the size of the Leydig and the Sertoli cells, the efficiency of spermatogenesis (i.e. the number of male gametes produced by an A1 spermatogonium and the daily sperm production were all significantly reduced in the rams exposed to long days. There was a positive correlation between the concentration of FSH and testosterone and many of the cytological changes consistent with a causal role for these hormones in mediating the effects of photoperiod on the testicular function in the ram.

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M. de la Lastra, Lili Bravo and Rosa Arriagada

Summary. Ovulation was induced in aminophylline-treated rats by different stimuli acting upon the pituitary gland (LH-RH in pro-oestrous rats treated with chlorpromazine), ovary (LH in pro-oestrous rats treated with chlorpromazine or hypophysectomized) or ovary and pituitary gland (PMSG in immature rats). In the different assays, the proportion of ovulating rats and the number of eggs ovulated were augmented by aminophylline treatment. Immature rats injected with aminophylline 1 day after priming with PMSG had, between 18:00 and 20:00 h, significantly higher blood LH levels than did controls.

Chlorpromazine injected at 10:00 h on the day of pro-oestrus inhibited ovulation and suppressed the LH surge normally observed at 18:00 h. However, aminophylline injected at 13:00 h re-established ovulation and induced within 1 h a slight LH secretion.

The results indicate that aminophylline affects both pituitary gland and ovary, supporting the concept that their cAMP levels play a significant biological role in the magnitude of the ovulatory response.

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M. De, T. R. Sanford and G. W. Wood

Interleukin 1 (IL-1), IL-6 and tumour necrosis factor alpha (TNF-α) are expressed in the mouse uterus on days 1–3 of pregnancy. Cytokine production is temporally associated with the post-mating intrauterine acute inflammatory response. In this study, IL-1, IL-6 and TNF-α were detected in the uterus of pregnant mice from day 3 to day 9, using northern blotting, bioassays and immunocytochemistry. IL-1 bioactivity increased from a low concentration on day 3 to a peak between days 4 and 5 and decreased to low concentrations on days 7 and 8. Blastocyst implantation occurs late on day 4. IL-6 bioactivity was high from day 3 to day 9 and activity was maximal on days 5 and 6. TNF-α bioactivity increased from its lowest concentration on day 3 to a peak on day 8. Although changes in bioactivity concentrations occurred at different times from changes in mRNA concentrations, the changes were approximately parallel. Translation of mRNA into an immunologically detectable product was confirmed using immunocytochemistry with polyclonal anti-cytokine antibodies. We conclude that the cytokines IL-1, IL-6 and TNF-α are produced in the uterus during the periimplantation period of pregnancy in mice. Changes in cytokine concentrations suggested the existence of some form of regulated expression.

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JoGayle Howard, M. Bush, V. de Vos and D. E. Wildt

Summary. A regimented electroejaculation protocol (120 electrical stimulations; 10-30 V) was used to collect semen and characterize ejaculate quality from 9 adult, free-ranging African elephants under anaesthesia. Eight of the 9 ejaculates contained high concentrations of progressively motile spermatozoa. The overall mean ejaculate volume, sperm concentration/ml ejaculate, sperm motility, sperm status and ejaculate pH were 93·3 ml, 2408·6 × 106 spermatozoa/ml, 70%, 3·9 and 7·4, respectively. A high percentage (mean 77·5%) of spermatozoa within each ejaculate was morphologically normal. Of the aberrant spermatozoa, 72% had a cytoplasmic droplet defect. When sperm viability was tested in vitro at 37°C, sperm motility rating declined by at least half of the initial assessment within 3·5 h of semen collection. Generally, spermatozoa maintained motility in vitro for < 6 h. Serum testosterone ranged from 1·4 to 8·2 ng/ml in 4 males evaluated in the morning (07:30–08:00 h). In 4 of the 5 bulls assessed in the afternoon (15:00–18:00 h), testosterone levels were <0·9 ng/ml. The remaining bull, evaluated at 16:00 h, had exceptionally high testosterone concentrations (peak 25·6 ng/ml) and a preputial discharge potentially indicative of 'musth'. The present study demonstrates that high quality semen can be collected consistently from the African elephant and that striking differences exist in serum testosterone amongst free-ranging males which may be due, in part, to a diurnal rhythm.