Ontogeny and localization of the crystallins during lens development in normal and Hy-1 (hyperplastic lens epithelium) chick embryos.

A strain of chickens selected for high growth rate has been found to exhibit an anomalous eye lens morphology indicating a failure of the normal process of growth regulation. Hyperplasia of the lens epithelium and annular pad, often with fiber formation, has recently been described in day-old chicks of this strain, termed Hy-1 (Clayton, 1975). The earliest evidence of this condition in this study has been found in the 11-day embryonic Hy-1 lens. Before this time, no definitive lens abnormality could be detected histologically in the Hy-1 embryos. However, the indirect immunofluorescence technique had revealed early temporal and spatial differences with regard to the lens crystallins. Antibodies, specific for delta, cathodal beta, anodal beta and alpha crystallins, were applied to sections through the lens of 2 1/2-, 3-, 3 1/2, 4-, 5-, 8- and 16-day embryonic and 1-day post-hatch normal and Hy-1 chicks. delta crystallin appears precociously in the external layer, and alpha crystallin in the prospective fiber region, of the lens rudiment of Hy-1 embryos. Both anodal and cathodal beta crystallins are retarded, however, in their appearance in the external layer/epithelium of Hy-1 lenses. Localization of the crystallin classes within the lenses of the two strains continues to vary during lens differentiation until 1 day post-hatch, at which time and during late embryogenesis annular pad and epithelium abnormalities can be frequently be seen in the Hy-1 lens. This inability to control normal lens histogenesis thus manifests itself early as alterations in the appearance of an organ-specific gene product, the crystallins.