On the ultrastructure of the developing and adult mouse corneal stroma

The EM study of the mouse embryonic cornea from the 12th to the 19th day of gestation as well as on postnatal days 2 and 18 and on adult animals allow the following conclusions to be drawn: 1. Immediately after the separation of the lens vesicle, the mesenchyme cells migrate into the cornea anlage. 2. There is no collagenous primary stroma in the mouse embryo. 3. During days 12-14 the stroma cells (fibroblasts) differentiate and develop the organelles required for ICS (intercellular substance) secretion. 4. In the posterior region of the stroma, the collagen fibrils are deposited in bundles approximately perpendicular to each other. 5. The adult mouse stroma is divided into 2 zones. In zone I the subepithelial fibrils are randomly distributed and are not bundled (rudimentary Bowman's membrane). In zone II the fiber bundles lie in the plane of the cornea and form a highly ordered three-dimensional network. Basic differences between the mouse and other species are discussed.