Sequential differentiation of retinal cells in the mouse studied by diaphorase staining.

During retinal development in mice the early stages of differentiating of ganglion, amacrine and horizontal cells are characterized by high diaphorase activity in the perikarya. The reaction in the ganglion cells, which start differentiation at day 12 of gestation when the layer of nerve fibres is developing, was first localized near the axonal end, but later, in the period of dendritic growth, it shifted to the scleral side. Amacrine cells were first detected on day 16, and showed a transient activity at the initial stage of their differentiation. A variety of large amacrine cells with long bifurcating processes appeared at day 7 after birth, and showed particularly high TPN diaphorase activity. The horizontal cells could be followed from the 16th day of embryonic life. Their activity increased during the period of formation of the outer plexiform layer. Along the outer limiting membrane diaphorase activity was marked from day 13 of embryonic life, and seemed to concentrate later in the rod inner segments. Activity in the bipolar cells first appeared at day 7 after birth, and increased therafter, coinciding with the period of synaptic development in the outer, plexiform layer. Activity in the Müller cells appeared around 14 days after birth, and was most pronounced in the inner processes and basal end feet. The sequential differentiation of retinal cells and cellular interrelationships during retinal histogenesis are discussed.