Changes in retinoid binding levels during development of the chicken cornea.

[3H]-retinol binding to cellular retinol-binding protein (CRBP) increased more than five-fold in developing chicken corneal epithelium at 14 days of incubation, the time when the initial increase in corneal transparency occurs in the developing embryo. In contrast, [3H]-retinoic acid binding to cellular retinoic acid-binding protein (CRABP) was highest at the earliest stages and decreased progressively to a very low level in the corneal epithelium near the time of hatching. Thus, there appear to be changing and differing requirements for retinol and retinoic acid during development of the chicken cornea.