Beta- and gamma-crystallin synthesis in rat lens epithelium explanted with neural retinal.

The main aim of this study was to determine whether the neural retina brought about the qualitative changes in protein synthesis associated with lens fibre differentiation. Explants of lens epithelium from newborn rats which only contain alpha-crystallin in detectable amounts were cultured alone or on pieces of neural retina. In the latter case the explants increased in size and contained alpha-, beta-, and gamma-crystallins. This size increase and change in crystallin composition is characteristic of lens fibre differentiation from epithelial cells. To determine if this was a specific property of the neural retina the epithelium was grown on other tissues. Corneal stroma and cartilage brought about some differentiation in the presence of foetal calf serum but were not as effective as the neural retina. Dermis had no effect on differentiation of the lens epithelium. One interpretation of these results is that the neural retina simply provides a good substratum on which the epithelium can grow and differentiate. However, epithelial explants grown in retina-conditioned medium also differentiate. Therefore the explant response must be a result of the modification of the medium by the neural retina.