Determination of the developmental pattern of retinal ganglion cells in chick embryos by Golgi impregnation and other methods.

The differentiation of retinal ganglion cells was investigated in chick embryos, with special attention to accurate incubation times from stage 20 (about 3 days of incubation) to after hatching (after 20 days of incubation). The morphological differentiation of these cells comprised four main events: 1. Shortening of the bipolar processes attached to the inner and outer limiting membranes and the sprouting of an axon from part of the cell body. These were recognized at stage 25 (about 4.5 days of incubation) by Golgi impregnation methods. 2. Beginning of differentiation of the dendrites, which was recognized at stage 29 to 31 (about 6 or 7 days of incubation). 3. The rapid development of the dendrites. This occurred at stage 34 (about 8 days of incubation). 4. The essential completion of the retinal ganglion cells, which was recognized at stage 39 (about 13 days of incubation).