Development of dopaminergic neurons is insensitive to optic nerve section in the neonatal rat retina

The development of tyrosine-hydroxylase-immunoreactive (TH-IR) cells was studied in pre- and postnatal rat retinas. Using a modified staining 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-IR cells were always concentrated at the peripheral dorsal part of the retina, in contrast to the expected distribution predicted by the center to peripheral gradient of retinal development. The development of TH-IR cells and their pattern of distribution were insensitive to optic nerve section, indicating that the postnatal development of dopaminergic neurons is independent of the presence of ganglion cells.