Figure 4. Histological examination of the lens. Epon semi-thin sections were stained with toluidine blue. A: The control animal is shown. A single layer of the cuboidal epithelium (arrow) transforms at the equator into elongated cells representing future lens fibers. B: The lens of +/Dca heterozygotes corresponded in shape nearly completely with that of control animals. At low magnification, the most pronounced feature of the lens is marked heterogeneity in the stainability of its fibers. The lens capsule has often variable thickness and is almost regularly thicker at the anterior face. Persisting vascularization in the posterior eye chamber can be observed. C: In +/Dca heterozygotes, at the higher magnification and tangential section plane orientation, irregularly dilated intercellular spaces between anterior cuboidal epithelial cells (arrows) and newly formed lens fibers can be demonstrated. D: Severe alterations of lens development were found in homozygous Dca/Dca animals with microphthalmic eyes. The equatorial region forms a regularly sharp angle with a distinct thickening of the lens capsule. The anterior epithelium is discontinuous, and sometimes there are only isolated groups of epithelial cells visible at the anterior face of the lens. Abundant dilatations of intercellular spaces can be seen in some lens regions as great vacuolar formations. Also, stainability of lens fibers increases toward the central part. E: Higher magnification of Dca/Dca lens reveals findings similar to those in D; missing continuity of the anterior cuboidal epithelium and striking disturbances in organization and arrangement of cell to cell contacts.