Reproduction in the mountain possum, Trichosurus caninus (Ogilby), in captivity

Abstract

Reproduction was studied in eight female T. caninus held in captivity in Armidale, N.S.W., for up to 5 yr. Oestrus was diagnosed from the vast increase in epithelial cells in the vaginal smear, post-oestrus being detected by the appearance of many leucocytes and of some elongate epithelial cells. The mean of 17 oestrous cycles was 26.4+- 1.0 days and the mean of 10 gestation periods was 16.2+-0.2 days. The teats evert and the female first ovulates at the end of her 2nd year, but no captive female gave birth till near the end of her 3rd year. In the anatomy of the uteri and vaginae, T. caninus resembles T. vulpecula but the ovaries of T. caninus are markedly distinguished by the presence of up to seven large corpora lutea. Although the weight of the luteal tissue may contribute as much as 83.9 % of the total ovarian weight, there is no evidence from the uteri that these large corpora lutea are functional in hormone secretion. The luteal cells are large but vacuolated and are separated by a well developed network of connective tissue. As the corpora lutea persist throughout the life of the animal, it is suggested that their number be used to indicate the maximum age of the animal.