Chemospecificity of ontogenetic units in the striatum: demonstration by combining [3H]thymidine neuronography and histochemical staining.

Abstract

Neurons being generated in the striatum o 10 fetal cats were pulse labeled by injection of [3H]thymidine directly into the maternal uterus at times ranging between the 22nd-30th day (E22-E30) of the 65-day gestational period. Many of the striatal neurons labeled during this interval were found, at adolescence, to form 100- to 600-.mu.m-wide cell clusters in the caudate nucleus. In E24-E30 specimens, the distributions of these cell clusters were compared with the locations of patches of low acetylcholinesterase activity and high enkephalin immunoreactivity (the striosomes) visualized in serially adjoining sections. Precise matches were found between most of the cell clusters and the acetylcholinesterase-poor enkephalin-rich zones, regardless of the embryonic age at which exposure to the [3H]thymidine occurred. Histochemically distinct striosomal patchworks observed in the acetylcholinesterase and enkephalin preparations apparently correspond to ontogenetic units of the striatum.