Testosterone modulation of the male marsupial Metachirus nudicaudatus paracloacal (scent) glands

Abstract

We investigated the possible influence of androgens on the odoriferous (scent) glands of the neotropical male marsupial Metachirus nudicaudatus. Glands of control animals from wild populations in the breeding and non-breeding seasons were compared with the ones of castrated animals. Radioimmunoassay was used to detect testosterone levels in all studied groups. When compared with the major (yellow) and the minor (brown) glands in the breeding season, the yellow gland was larger in two of three animals. In the non-breeding season, they were closely the same size, whereas in castrated animals, the major glands were smaller than the minor ones. The number of layers of the holocrine secretory epithelium and the mean cell area of the major (yellow) gland were also well developed in the breeding season (8–12 layers) in contrast to non-breeding (1–9 layers) and castrated animals (1–5 layers). There was no significant difference in the minor (brown) gland concerning the gland volume and the number of layers of the holocrine secretory epithelium in all surveyed groups. The mean cellular areas of tubular glands inserted in yellow glands of the breeding season were larger than those in the non-breeding season and castrated subjects. On the other hand, some variations observed in the average cell areas of the brown glands did not obey the standard of testosterone activity. In conclusion, the major (yellow) paracloacal gland of Metachirus nudicaudatus males is under the influence of testosterone, while the minor (brown) gland is not.