Abstract
Keratins (Ks) expressed in the absorptive cells of rabbit duodenal epithelium were studied immunohistochemically and immunoelectron microscopically. These keratins were classified into three groups based on their distribution: keratins forming an apex network just under the terminal web, those forming a Golgi-associated network surrounding the Golgi apparatus, and those forming an entire cytoplasmic network. The apex network was composed of K5/K18 keratin filaments. The Golgi-associated network at first consisted of K8/K14 keratin filaments alone. When the cell migrated out of the crypt to the mid-villus, actin and K7/K17 keratin filaments successively entered this network. The entire cytoplasmic network was detected at the villus base, and consisted of K7/K17 keratin filaments. Thereafter, K5/K18 keratin filaments entered this network during migration of the cell. The apex network may serve to maintain cell-cell contact, since its filaments are tightly anchored to desmosomes. The Golgi-associated network may be involved in the maintenance of the complex structure of the Golgi apparatus, since its filaments constitute a three-dimensional network around the organelle. The entire cytoplasmic network may play a major role in the maintenance of cell structure and the distribution of cell organelles.
