Studies on the vaginal mucusof the marsupial Trichosurus vulpecula

Abstract

The vaginal mucus of T. vulpecula is secreted by the simple columnar epithelium of the vaginal cul-de-sac and upper portion of the lateral vaginal canals. Vaginal mucus was present in measurable quantities for a period of only 3-4 days: from the commencement of oestrus (as judged by vaginal smears) until about half a day after ovulation. Over this period the volume of mucus in the cul-de-sac rose rapidly from practically nil to about 3.5 ml at ovulation. Following ovulation, the volume very soon returned to its former level. Treatment of anoestrous animals with doses of oestradiol benzoate at 40ug/kg body weight daily for 2 or 4 days, and 20 or 40 ug/kg body weight for 8 days, resulted in secretion of mucus in similar quantities to that found in oestrous animals. Preliminary studies of the physical properties (density, percentage dry matter, viscosity, and "stickiness") of the vaginal mucus of T. vulpecula revealed few trends that could be causally related to follicle development, oestrus, and ovulation. However, the pH appeared to follow a trend with regard to follicle development. It was found to fall from 7-8 to 6 at the end of follicle growth. The histochemical findings suggest that the vaginal mucus of T. vulpecula is a carbohydrate-protein com- plex, containing neutral sugars and acidic mucopolysaccharides. The acidic mucopolysaccharides are mainly carboxylated; however, low concentrations of sulphated mucopolysaccharide are also evident. The presence of appreciable quantities of free vaginal mucus in the vaginal cul-de-sac between oestrus and ovulation suggests that it is likely to be functionally important in the maintenance of a sperm reservoir.