Studies of the cutaneous glands and hair follicles of some species of Macropodidae

Abstract

Histological studies were made on skin samples from wild red kangaroos, Megaleia rufa (Desmarest), grey kangaroos, Macropus canguru (Miiller) syn. M. giganteus and M. major of three colour variants, euros, Macropus robustus Gould, and one swamp wallaby, Protemnodon bicolor (Desmarest). The hair cover was densest in the mid-dorsal region of the body, on the cheeks, and on the shoulders and the thighs. The density decreased ventrally. On the tail the hair follicles were less dense on the ventral than on the dorsal surface. The red kangaroo had the densest hair cover. The thickness of the hair fibres varied inversely in relation to the density of hair cover. Hair follicle grouping on the ventral surface of the tail was characteristic for each species and the hairs there uniformly resembled bristles. Males of all species, except the euro, were found to have consistently thicker skin on the ventral surface of the body but in females the skin was thicker on the back. In the tails of both sexes of all species the skin was thicker on the ventral than on the dorsal side. The thickness of the papillary layer on the ventral surface of the tail was correlated with the size of the animal and it is suggested that it may possibly be used as a measure of age. The complete absence of a reticular layer was noted in the skin of all species of macropods examined. The type and distribution of sweat glands was studied and sex, age, and species differences were demonstrated. Euros were found to have sweat glands with a characteristically bulbous lower part, in addition to the types of sweat glands present in the other species. In males of all species highly convoluted apocrine glands occurred in the breast and axillary regions while in females they were most common in the cloaca-pouch area. The behavioural importance of the secretion of these glands is suggested. Histological differences in the skin of the three colour variants of the grey kangaroo are described and the taxonomic value of skin characteristics is suggested.