Development of the macular circulation.

The development of the primate retinal vasculature has been investigated in fetal monkeys (M. mulatta) during the latter half of gestation. Vascularization is found to be retarded in the region of the macula. The macula is found to become completely encircled by a network of primitive capillaries which then proliferate centripetally towards the presumptive fovea. These encircling vessels normally cease to proliferate before reaching the center of the fovea, and the resulting central avascular zone and centripetal pattern of vessels persist thereafter in the mature macula. The superficial peripapillary network of capillaries, like the outer vascular net, is found to be derived from the inner network of vessels.