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Abstract
The synthesis of crystallins was studied in chicken embryos of 48 hours up to 8 days of incubation, by means of the indirect fluorescent antibody technique. The first positive reactions were observed in 23 somite embryos (50 to 53 hours of incubation). A few cells in the morphologically most advanced area of the lens placode showed fluorescence. With the deepening of the placode the reaction gradually spread to more exterior parts, concomitant with signs of morphodifferentiation. At 3 to 3.5 days of embryonic life both anterior epithelium and fibers were positive. Intra- and extra-embryonic ectoderm, neural tissues, and optic cup and its derivatives did not show fluorescence in any of the stages studied. On the basis of these and of earlier residts current theories regarding lens induction in the chicken embryo are rejected. It is assumed that the onset of crystallin synthesis may be dependent on gene activation in the lens cell nuclei under the influence of retinal factors. Some other theoretical aspects of lens differentiation are discussed