Interkinetic nuclear migration during the early stages of lens formation in the chicken embryo

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Abstract
The optic vesicle in the chicken embryo, after growing out sufficiently to establish contact with the overlying ectoderm, adheres very firmly to the latter for a period of 12–15 h (McKeehan, 1951). Within the area of adhesion the surface ectoderm is transformed into a lens placode under influence of the developing retina. Little is known about the biochemical changes involved in this tissue transformation. Langman (1959) and Langman & Maisel (1962) found a cytotoxic effect of lens protein antisera and specific α-crystallin antibodies on presumptive lens cells shortly after induction had started but before the first morphological changes characteristic for the lens placode were visible. They concluded that the synthesis of α-crystallin might be a prerequisite for lens placode formation. Recent studies with the fluorescent antibody technique, however, indicate that the first crystallins are not produced until the very end of the contact period (Zwaan & Ikeda, 1965,1968; Ikeda & Zwaan, 1966).