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 immunofiuorescence technique had revealed early temporal and spatial differences with regard to the lens crystallins. Antibodies, specific for δ, cathodal β, anodal β and α crystallins, were applied to sections through the lens of 2½-, 3-, 3½-, 4-, 5-, 8- and 16-day embryonic and 1-day post-hatch normal and Hy-1 chicks. δ crystallin appears precociously in the external layer, and α crystallin in the prospective fiber region, of the lens rudiment of Hy-1 embryos. Both anodal and cathodal β 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.
