Distribution of carbonic anhydrase isozyme VI in the developing bovine parotid gland.

The distribution of bovine carbonic anhydrase isozyme VI (CA-VI), purified from bovine saliva, was studied immunohistochemically using antiserum against bovine CA-VI in bovine parotid glands during fetal and postnatal development. A weak expression of CA-VI in undifferentiated epithelial cells and ductal cells was observed in a 4- to 5-month-old fetus with a 26-cm crown-rump length. The reaction in both acinar and ductal cells subsequently persisted during late gestation and birth. Although anti-CA-VI reactivity was still seen in both regions immediately following birth, the reactivity had almost completely disappeared from most duct segments by 1 month following birth. Changes in the localization and time-dependent expression of the isozyme in parotid glands may reflect changes in the biological function of structurally closely related isozymes.