Distribution of cytokeratin polypeptides detected by monoclonal antibodies K8.13 and K8.12 in the fetal bovine ruminal epithelium.

Temporal and spatial distributions of cytokeratin (CK) polypeptides were detected by monoclonal antibodies (mAbs) K8.13 and K8.12 during the development of the bovine ruminal epithelium. By the Western blotting analysis after the sodium dodecyl sulfate-polyacrilamide gel electrophoresis, mAb K8.13 confirmed 60.8 and 63.0 kD CK polypeptides in the fetal ruminal epithelial extract, and mAb K8.12 also 48.0 and 54.0 kD CK polypeptides. Immunohistochemical reactivities against both mAbs were detected only in the epithelial cells throughout the fetal periods. Distributions of CK polypeptides detected only by mAb K8.13 were observed on the basal side of the epitherial layer, but not by mAb K8.12 in the 7 cm fetus in crown-rump length. MAb K8.13 reacted also intensely with columnar-shaped cells in the basal layer in the fetuses of the later developmental periods. These results suggest that CK polypeptides detected by mAb K8.13 might be involved in the differentiation and/or the maintenance of the basal layer in the ruminal epithelial development.