DEVELOPMENT OF DOPAMINERGIC-NEURONS IN INSENSITIVE TO OPTIC-NERVE SECTION IN THE NEONATAL RAT RETINA

The development of tyrosine-hydroxylase-immunoreactive (TH-IR) cells w as studied in pre- and postnatal rat retinas. Using a modified stainin g method, TH-IR cells were first detectable in retinal wholemounts at embryonic day 19 (E19), much earlier than previously reported. By E20, TH-IR cells were present in every retina examined. These 'early' TH-I R cells were always concentrated at the peripheral dorsal part of the retina, in contrast to the expected distribution predicted by the cent er to peripheral gradient of retinal development. The development of T H-IR cells and their pattern of distribution were insensitive to optic nerve section, indicating that the postnatal development of dopaminer gic neurons is independent of the presence of ganglion cells.