Distributions of fibronectin, laminin, type I and IV collagens and carbonic anhydrase isozyme III during bovine ruminal epithelial development.

The present study describes the immunohistochemical distributions of extracellular matrices and the carbonic anhydrase isozyme III (CA-3) in the bovine ruminal epithelium during fetal development. Fibronectin (FN), laminin and type I and IV collagens were distributed in the ruminal subepithelial mesenchymal regions with nonspecific regionality during the gestational periods. At stages after about 59 cm crown-rump length (CRL), FN of the epithelial basement membrane disappeared, and CA-3 appeared in the basal epithelial cells of the root of the ruminal papillae, suggesting that the functional differentiation of the ruminal epithelium might start at around 59 cm CRL in bovine fetuses.