Congenital eye defects in the mouse. I. Corneal opacity in C57Black mice

Corneal opactities are observed in a small percentage of C57Black mice. Discrete central opacities are found in eyes of normal size; more generalized opacities are found in eyes which are reduced in size, although large enough to protrude through the eyelids. Corneas with discrete opacities are characterized by a gap in the stroma, and disorganization of the overlying epithelium. Similar stromal defects are found in corneas with more generalized opacties, and, in addition, cornea and iris are continuous along their stromal components. Either anterior polar cataract or anterior lenticonus, defects involving the anterior surface of the lens, are almost invariably found in association with the corneal opacities. Study of early lens and corneal development in C57Black embryos implicates prolonged attachment of the lens vesicle to the superficial ectoderm in the genesis of the corneal opacities. The persistence of the lens stalk serves as a barrier to migration of the mesenchyme involved in formation of the corneal stroma. Migration of the mesenchyme destined for a role in development of the stroma of the iris may also be hindered. Separation of the lens vesicle from the superficial ectoderm takes place eventually, but stromal development remains defective. Disorganization of the corneal epithelium appears to be a secondary consequence of the defective stroma. Anomalies of the anterior surface of the lens appear to result from problems associated with the abnormal separation of the lens vesicle from the superficial ectoderm.