Mitotic activity in the cortical vitreous cells (hyalocytes) after photocoagulation.

After photocoagulation of the rabbit retina wound healing occurs with a marked increase in mitoses not only in choroid, pigment epithelium, and retina, where mainly Midler cells are proliferating, but also in the cortical vitreous cells, the hyalocytes. The rate of mitosis in the hyalocytes ivas investigated by administration of systemic colchicine. The rate of mitosis is highest around the third to the fifth day post photocoagulation. In localized areas near the region of photocoagulation and in more diffuse areas in the zonular region corresponding to the equatorial band of coagulation the rate of mitosis reaches values of up to 100 mitoses per 1,000 cells, when colchicine is in effect for four hours. This is at least five or more times higher than in control eyes. The rate of mitosis is high enough to explain, in large part, the increase in the cell population in the vitreous. The possible relationship between proliferation of hyalocytes after photocoagulation and epiretinal fibroplasia and massive preretinal retraction is discussed.