[Scanning electron microscopic observation on altered fenestration of the choriocapillaris in sodium iodate-treated rats]

Fenestration of the choriocapillaris may be lost and regained in various pathologic conditions. The purpose of this study was to observe the gradual disappearance of fenestrae with the scanning electron microscope. Pigmented rats were treated with an intravenous injection of sodium iodate. Changes in the choriocapillaris were produced by damaging retinal pigment epithelium. The eyes were processed for styrene embedded cracking on the third, fifth, and seventh days. Dense clusters of fenestrae were seen at the luminal surface facing retina on the third day. These clusters were surrounded by protrusion of cellular surface. The clusters of fenestrae were smaller with some variation in size on the fifth and seventh days. The protrusion between the clusters became flatter and wider. Some endothelial cells had a flat surface with tiny clusters of fenestrae. Although there was loss of fenestrae with smaller clusters and some variation in size, the tendency of the fenestrae to cluster was sustained in the same way as during the reformation of fenestrae in the choriocapillaris after laser photocoagulation.