Histological structure and distribution of carbonic anhydrase isozymes (CA-I, II, III and VI) in major salivary glands in koalas.

While the mandibular glands usually consist of only mucous acinar cells or a combination of mucous and serous cells in other species of mammals, those of koalas were serous glands. Rabbit mono-specific polyclonal anti-canine CA-I, II, III or VI antiserum showed cross-reactivity against corresponding koala carbonic anhydrase (CA) isozymes. Although immunohistochemical reactions to CA-I, II and VI in ductal cells were moderate to strong in the tested salivary glands, no reaction or only slight reactions were observed against CA-III. In the sublingual glands, moderate immunohistochemical reactions to CA-I, II and VI were also evident in serous acinar cells and serous demilunes. However, no reactions to the tested isozymes were observed in mucous acinar cells in these glands. With the exception of the histological structure of the mandibular glands, histological features and the distributional profile of CA isozymes of the salivary glands in koalas are relatively close to results obtained from horses.