Salivary glands of kangaroos

Abstract

The position and histological appearance of the parotid, submaxillary, and sublingual glands in five red kangaroos (Megaleia rufa) and six grey kangaroos (Macropus giganteus and M. fuliginosus melanops), including pouch young, are described. The parotid of adult kangaroos, although histologically similar to that in calves and sheep, was twice as heavy in relation to body weight. The submaxillary was of similar weight, in relation to body weight, as the submaxillary of the ruminants, but had a much greater proportion of serous-type secretory cells than the submaxillary of sheep. Weights of the three types of glands were all significantly correlated with empty body weight. The glands, particularly the parotid gland, were incompletely developed even in advanced pouch young (250 days). Saliva secretion was stimulated electrically in an anaesthetized red kangaroo (M. rufa) and parotid and submaxillary saliva samples were collected via cannulae in the ducts. The ionic composition of these samples resembled that of sheep and calf saliva more than that of non-ruminants. It had high sodium and bicarbonate concentrations which would afford good buffering capacity. However, the kangaroo parotid saliva contained amylase, which is not found in ruminant saliva.