Development and characterization of the lens capsule of mouse embryos (day 12 to day 19 of gestation).

The development of the lens capsule (LC) of mouse embryos was investigated between days 12 and 19 of gestation using immunomorphological (collagen type I, II, III or IV, laminin, BL-heparan sulfate, fibronection) and electron microscopic techniques. The lens capsule contains the typical components (collagen type IV, laminin and BL-heparan sulfate) of the basal lamina (BL) and can therefore be considered as thickened BL. Tannic acid fixation is especially suited for an electron microscopic demonstration of the lens capsule. The development of the lens capsule starts on day 12 of gestation. Its thickening is due to BL accumulation from the outside. This mode of thickening can be explained by the tendency to two-dimensional self assembly of collagen type IV. Electron-dense granules occur in the basal cytoplasm of lens epithelial cells. These granules can be considered as secretion granules. Their increased occurrence towards the end of gestation is attributed to a delayed secretion rather than to an increased synthesis.