Lentoidogenesis from neural retina cells in culture is affected by interactive relationships between different cell types.

By centrifugation in a Percoll gradient, two cell fractions were separated from cell populations harvested from 8-day cultures of neutral retina cells of 3-5-day-old quail embryos. The heavy (H-) fraction contained mostly N-cells, which are considered to be putative neuronal cells, while the light (L-) fraction contained both E-cells, putative retinal glial cells, and N-cells. Determination of choline acetyltransferase activity in both fractions suggested that this enzyme is predominantly localised in N-cells. After replating the separated L-fraction for further culturing, frequent lentoidogenesis occurred from clusters of N-cells which, though few in number, were included in this fraction. Addition of H-fraction to L-fraction cells caused a significant increase in lentoidogenesis up to a ratio of N- to E-cells of 3:1. However, addition of excess H-fraction cells beyond this ratio inhibited lens differentiation. This difference in the expression of lens phenotypes resulting from the different ratios of H- and L-fraction was confirmed by monitoring the level of delta-crystallin in cultures. These results are discussed in the light of interactive relationships between N- and E-cells in the transdifferentiation of neural cells into lens in cell culture.