IN VITRO DIFFERENTIATION OF CHICK EMBRYONIC LENS EPITHELIAL CELLS INTO FIBER CELLS

The processes of fiber-cell formation in the lens epithelium of 9-day-old chick embryo in vitro were studied. Mitotic activity was enhanced during the first 12 hr, but with a drop at the 4th hour of cultivation. After the 24th hour, when the cells began to elongate, almost no mitotic figures or incorporation of 3 H-thymidine into the nuclei were observed. α- and δ-crystallin were contained in and synthesized by the newly isolated lens epithelium. The content and syntheses had diminished by the 12th hour. In the earlier phase of cultivation, both fiber cell formation and crystallin synthesis were suppressed by treatment with Actinomycin D, but after the 12th hour they were resistant to the antibiotic. The correlation between cell division and fiber-cell differentiation in the lens epithelium in vitro is discussed and compared with that reported in Wolffian lens regeneration and in developing bovine lens.