Transferrin enhances lentoid differentiation in rat egg cylinders cultivated in a chemically defined medium

Rat egg cylinders at the primitive streak stage were grown in modified organ culture for 2 weeks using a chemically-defined medium. The purpose of the experiment was to determine whether the terminal tissue differentiation is modified by human transferrin. The control sets were grown in medium with or without rat serum. In explants treated with transferrin, groups of atypical cells of the ocular lens (lentoids) appeared more frequently than in both control sets; however neuroblasts were observed as often as in the serum-supplemented medium. Bovine serum albumin (BSA) stimulated the differentiation of neuroblasts but did not promote lentoid formation. We conclude that human transferrin does stimulate the differentiation of lentoids in rat embryonic explants, but the mechanism of its action remains unknown.