Ultrastructural evidence of remodelling in the microvasculature of the normal rabbit and human eye.

Several investigators have recently presented ultrastructural evidence for remodelling in the mammalian, including human, choriocapillaris. This evidence consists of cytoplasmic processes off endothelium and pericytes that penetrate the basal lamina of the capillary and enter the pericapillary space and redundant layers of basal lamina interpreted as the result of secretory activity subsequent to cellular movement within the wall of the capillary. This report extends these observations to the remaining microvasculature of the choroid--its arterioles and venules--and to another part of the ocular microvasculature--the pars plana of the ciliary body--of the rabbit and human eye. Cytoplasmic processes and redundant basal laminae were observed in the microvasculature at both sites, most frequently associated with venules and capillaries. Cytoplasmic processes and redundant basal laminae are generally associated with cellular movement and vessel growth during ocular neovascularization. However, their presence in histologically normal eyes suggests that these phenomena occur in the absence of neovascularization, i.e. that the microvasculature is remodelled in the normal eye.