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Summary. The epididymides of adult male hamsters were surgically ligated at the junction of the distal corpus and proximal cauda regions. After 3 days, spermatozoa recovered from the distal corpus displayed greater progressive motility and head to head agglutination in capacitating medium than did those from intact controls, but had low fertilizing ability (3% fertilization rate) in vitro or in vivo. When these spermatozoa were incubated for 6 h with epithelial cells from the proximal cauda epididymidis, previously cultured for 3 days, they maintained motility and exhibited a significant increase in fertilizing ability (30% and 29% in vitro and in vivo respectively). The fertilizing ability of distal corpus spermatozoa incubated with 3-day-old cultures without androgens, or 8–12-day-old epithelial cells with fibroblast overgrowth, or without epithelial cells, remained low (5%). Increase in sperm fertilizing ability was associated with increased sperm binding to the zona pellucida in vitro.

These results demonstrate that, under suitable culture conditions, the final stages in the development of hamster sperm fertilizing ability can be achieved in vitro. Factors secreted by cultured epithelium from the proximal cauda epididymidis are implicated in this maturation process.

Summary. To determine the importance during fertilization of various plasma membrane components of the hamster spermatozoon, monoclonal antibodies were generated in the mouse against specific sperm surface antigens. BALB/C mice were immunized with washed hamster spermatozoa from the cauda epididymidis and immune splenocytes fused with myeloma cells (P3 × 63 Ag8). The sperm-specific immunoglobulins were detected in hybridoma cultures by a solid-phase assay (ELISA). Five monoclonal antibodies bound specifically to the surface of intact hamster spermatozoa, three immunoglobulins to restricted regions of the head and tail plasmalemma as detected by immunofluorescence. In two cases, the affinity of the membrane antigen was modified during passage through the epididymis. Monoclonal antibodies to the sperm head or to the head and tail inhibited fertilization in vitro by blocking sperm attachment to the zona pellucida and the oolemma.

Summary. Epithelium from the proximal corpus region of the epididymis of adult hamsters was cultured in modified RPMI 1640 medium supplemented with growth factors and androgens at 37°C in 5% CO₂ in air. Prepared plaques of epithelium formed spheres of tissue with epithelial cells outermost. At the light and electron microscope level, these epithelial balls displayed morphology consistent with continued secretory and absorptive function. After 3–5 days, cultured cells either plated out over the bottom of plastic wells or formed vesicles which expanded as their interior became fluid filled.

Spermatozoa recovered from the caput epididymidis were co-cultured with epithelium. After 8 and 24 h, a proportion of spermatozoa (30%) exhibited slow but persistent flagellum beats with slow progressive motility. Spermatozoa in control incubations were immotile. This change in motility pattern would suggest that some sperm maturation processes had occurred in vitro.

Summary. A murine monoclonal antibody raised against hamster cauda epididymal spermatozoa was shown to recognize an M _r 34 000 component of epididymal epithelium. Antigen was localized by immunocytochemistry on the surface and in the apical cytoplasm of principal cells in the proximal corpus epididymidis but not in the caput or initial segment regions. Spermatozoa from the corpus epididymidis expressed antigen on their post-acrosomal plasma membrane and annulus.

Epididymal principal cells from the proximal corpus region when cultured in vitro bound antibody on their apical surface for at least 5 days. Spermatozoa from the caput epididymidis co-cultured with epithelium expressed antigen after incubation for 8 and 24 h. These results suggest that a surface change to epididymal spermatozoa during maturation in vivo may also be elicited during in-vitro culture.

Summary. Hormonal detection of urinary pregnanediol-3α-glucuronide proved an effective method of monitoring the progress of oestrous cycles in the blackbuck; observation of sexual behaviour in a vasectomized male was, however, a more practical procedure. Good correlation was observed between the occurrence of minimal pregnanediol concentrations in females and the maximal behavioural response by the male. On the basis of intervals between periods of behaviourally detected oestrus, a mean cycle length of 16·9 days (± 0·62, s.e.m.) was derived from 12 cycles (4 animals).

Eleven females were inseminated in this study, 8 with freshly collected semen and 3 with frozen semen; 6 calves were obtained, 1 after the use of frozen semen. Pregnancy was monitored by measurements of pregnanediol-3α-glucuronide excretion and by ultrasound scanning. The mean interval between insemination and parturition was 183·3 days inclusive, ranging from 182 to 186 days.

Keywords: blackbuck; artificial insemination; oestrous cycles; oestrus detection; pregnancy