Histogenesis of the cat retina

Abstract

The development of the retina of the cat was studied with light and transmission electron microscopy from prenatal day 36 (E36) through postnatal day 9 (P9; eye opening), and at the adult stage (1 year). Tissue samples were taken from the posterior pole of the retina. At E36, the optic cup was completely formed, the pigment epithelium was a single cell layer, the retina consisted of an inner marginal fiber layer and an outer layer of neuroblastic cells, and the innermost cells of the neuroblastic cell layer, presumptive ganglion cells (which might still migrate through the inner plexiform layer) were displacing away from the neuroblastic cell mass. At E40, a distinct ganglion cell layer was seen. At E46, primitive horizontal cells appeared within the neuroblastic cell layer. Separation of the neuroblastic cell mass into inner and outer nuclear layers was first evident on E48; by E60, the layers were clearly separate. Conventional synapses were seen in the inner plexiform layer in the week prior to birth. Blood vasculature was observed prenatally as deep as the inner plexiform layer. In the newborn a few discs were seen in some photoreceptor cell outer segments. Synaptic ribbons appeared first in the outer plexiform layer in the newborn and then in the inner plexiform layer by P4.