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GEORGE K. SMELSER; Embryology and Morphology of the Lens. Invest. Ophthalmol. Vis. Sci. 1965;4(4):398-410.
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© ARVO (1962-2015); The Authors (2016-present)
The lens is derived from surface ectodermal cells which lie directly over the optic vesicle from which they are separated by the basement viembranes and a thin interepithelial space. Early differentiation, following induction, involves forming a compact disk of these epithelial cells in which the intercellular spaces have disappeared and their height increased. This disk or placode invaginates to form a vesicle surrounded by the basement membrane mentioned before. This becomes converted into the capsule. The cells of the posterior toall of the vesicle elongate rapidly, at this time, filling the vesicle and forming the primary fibers. Metamorphosis of the epithelial cells to fibers, both primary and secondary, consists of the formation of low density, diffuse clouds of minute fibrils. These are thought to be composed of the specific lens proteins, alpha, beta, and gamma crystallin. As these develop, the cytoplasmic organelles become reduced in number and segregated in the tips of the cells (fibers). Specific adult lens antigens are demonstrable as soon as morphological differentiation of the lens is observable. Experiments indicating an earlier appearance of these antigens are discussed. Induction of the lens is reviewed ivith emphasis on concepts which require "contact" between the optic vesicle and surface eotoderm, and the transfer of substances from the eye vesicle to the presumptive lens cells.
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