Embryology and Morphology of the Lens.
نویسنده
چکیده
The lens is derived from surface ectodermal cells which lie directly over the optic vesicle from which they are separated by the basement membranes and a thin interepithelial space. Early differentiation, folloicing induction, involves forming a compact disk of these epithelial cells in luhich 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 wall 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 cnjstallin. As these develop, the cytoplasmic organelles become reduced in number and segregated in the tips of the cells (fibers). Specific adult lens antigens are deinonstrable 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 eotodenn, and the transfer of substances from the eye vesicle to the presumptive lens cells.
منابع مشابه
Ontogeny of lens crystallins in marine cephalopods.
The ontogeny of the lens crystallin antigens throughout development of three marine cephalopod embryos, Loligo vulgaris, Sepia officinalis and Octopus vulgaris has been investigated using the indirect immuno-cytochemical staining against respective homologous anti-total lens protein antiserum. The cellular mechanism of lens development appears to be the same in all species investigated and so d...
متن کاملA light and electron microscopic study of cell behavior and microtubules in the embryonic chicken lens using Colcemid.
متن کامل
Abnormalities in the differentiation and cellular properties of hyperplastic lens epithelium from strains of chickens selected for high growth rate.
Similar morphological abnormalities of the lens of the eye of two unrelated strains of chicks, both of which had been selected for high growth rate, were found to be associated with epithelial cells showing marked deviations from the normal in cell surface properties, mitotic rate, capacity for differentiation, and in DNA, RNA and protein metabolism. The relationship between these modified prop...
متن کاملPermissive and directive interactions in lens induction.
The interactive events leading to lens formation and the developmental potentialities of the presumptive lens ectoderm were examined in vitro. The presumptive lens ectoderm of both mouse and chick embryos was capable of forming a lens even when isolated from the optic vesicle before the two tissues reach the stage of close association. This lens-forming bias can be released with favourable cult...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Investigative ophthalmology
دوره 4 شماره
صفحات -
تاریخ انتشار 1965