Growth of rabbit pigmented and nonpigmented ciliary body epithelium.

Pigmented (PE) and nonpigmented epithelial (NPE) cells were carefully dissected from the ciliary processes of rabbit eyes and maintained in vitro. Both epithelial cultured cells showed hexagonal morphology by light microscopy; abundant granules containing pigment could be seen in PE cells while no pigment was seen in the NPE cells. S-100 protein exists in both cultured cells and was used as a marker for the in vitro confirmation of these cells. Collagen type III was used as a negative marker to rule out stromal cell contamination in tissue cultures. PE cells attached and proliferated well in 20% fetal bovine serum (FBS) in minimum essential media (MEM). Greater proliferation was attained when PE cells were exposed to 20% vitreous extract in addition to 20% FBS-MEM. Media conditioned by PE cells did not significantly stimulate PE cells. NPE cells showed greatest proliferation in 20% FBS-MEM with either 20% concentration of media conditioned by PE cells or when exposed to 20% concentration of vitreous extract. Rabbit vitreous may contain factor(s) which stimulate the proliferation of both cultured cells, and conditioned media from the PE cells may contain factor(s) which stimulate NPE cell proliferation.