Electron Microscopic Analysis of Phagocytic Activity of Chick Embryonic Retinal pigment cells in vitro

The phagocytosis of latex particles by retinal pigmented cells from chick embryos was studied in vitro. The pigment epithelial cells phagocytized latex particles within 2 hr without a latent period, as found in some mamalian species. The number of latex phagosomes increased with time, and the phagosomes eventually became distributed nearly uniformly in the cytoplasm. When cultures that had been exposed to latex particles for 24 hr were incubated without the particles for a further 7 days, numerous latex phagosomes remained inside the cells without any decrease in their number. This indicates that phagocytized particles are not ejected from the cells, presumably due to a defect in, or absence of, exocytotic activity.