An immunohistochemical study on the tissue-specific localization of metallothionein in dogs.

To study the tissue specificity of metallothionein (MT) expression, tissues of dogs ranging in age from 1 day to 18 years were examined immunohistochemically. Of the organs examined, liver and kidney showed the strongest immunoreactivity; a comparable intensity of MT immunolabelling was noted in the two organs in adult animals. In the central nervous system, astrocytes and ependymal cells showed MT immunoreactivity. MT labelling was shown in the sustentacular cells of the olfactory epithelium, but immunoreactivity was slight in the epithelium of the respiratory tract. Slight MT immunoreactivity was demonstrated in the epithelium of a variety of glands (sweat, uterine, mammary, olfactory, perianal and thyroid) and in parietal cells of the fundic glands of the stomach. Sporadic MT immunolabelling was demonstrated in the columnar and goblet cells of the small and large intestines, surface mucosal cells of the stomach and epithelial cells of the hair follicles. These findings may help in understanding important features of MT, such as its dynamic induction mechanism, its systemic degradation pathway and the possible biological functions.