Morphology of pig retinal pigment epithelium maintained in organ culture.

Exoplants of porcine retinal pigment epithelium (RPE) attached to Bruch's membrane, choroid, and sclera were maintained in organ culture for up to four weeks. Four-millimeter round buttons of eye wall that contained RPE, choroid, and sclera were trephined from freshly enucleated pig eyes and incubated at 37 degrees C in Eagle's minimum essential medium with 10% fetal calf serum. The RPE cells remained as a monolayer for at least four weeks in organ culture, and individual RPE cells became taller and dome shaped. The RPE cells retained several prominent ultrastructural features, including apical microvilli, intracellular melanosomes and mitochondria, and intercellular tight junctions. Since the cellular substratum can exert important influences on cell behavior, the ability to maintain RPE cells attached to Bruch's membrane provides a new in vitro tool for studying the metabolic activity of this tissue and its response to external stimuli, including laser photocoagulation.