Tissue culture of the retinal pigment epithelial cells.

Pure culture of the retinal pigment epithelial (RPE) cells of the chick embryo was carried out and the morphological characteristics of each developmental stage were observed under light microscope and transmission and scanning electron microscopes. Immature cells had a few, short processes on the apical surface and a few melanin granules in the cytoplasm. However, mature cells had two types of processes on the apical surface, one being narrow and the other wide. Many melanin granules were diffusely dispersed in the cytoplasm and the cells were joined by a junctional complex near the apical portion. Beneath the cultured cells, basement membrane and collagen fibrils were evident and were apparently produced by the culture RPE cells. The structure of the cultured cells in the well-differentiated stage appeared to be the same as that of living cells.