Histogenesis of corticotropin releasing factor-like immunoreactive amacrine cells in the rat retina.

The histogenesis of amacrine cells expressing corticotropin releasing factor-like immunoreactivity (CRF-LI) was examined in the rat retina by incorporating [3H]thymidine autoradiography and immunohistochemistry. Our results indicate that, during the period of amacrine cell generation, the population of CRF-LI amacrine cells are generated within a window of time from gestational days (ED)-16 to -20; the majority of them are produced by ED-18. No CRF-LI cells have been found to be 'born' postnatally. The histogenetic pattern of these cells follows a center-to-periphery gradient. Furthermore, CRF-LI cells in both the inner nuclear layer and the ganglion cell layer are generated in the same histogenetic wave and follow an identical temporo-spatial pattern. These results are consistent with and extend our previous findings of a differential change in CRF-LI cell density and total cell number during postnatal development.