Apoptosis of the hyaloid artery in the rat eye

The hyaloid artery is a vestigial vessel situated on the optic nerve extend ing to the posterior surface of the lens in the vitreous cavity of the eye. We studied the nature and pattern of cell death during regression of the h yaloid artery. The cells comprising the hyaloid artery appear to be alive f or 20 days after birth in the rat, and cell death during regression of the hyaloid artery has the characteristics of apoptosis. We observed apoptotic bodies containing condensed chromatin and identified the hyaloid vessels as targets of macrophage-mediated remodelling. Using the "TUNEL method" for l abeling fragmented DNA in vascular cells, we assessed the pattern of apopto tic cell death during hyaloid artery regression. Our study demonstrated the appearance of apoptosis in pericytes as well as endothelial cells during r egression in the vasculature, In pericytes, apoptosis appeared to begin or to occur more frequently than in endothelial cells. Both morphological and TUNEL analyses indicated that capillary apoptosis occurs mainly from day 10 to day 20 after birth rather than from the 1st day, Macrophages were prese nt near the hyaloid artery and these may influence apoptosis.