Synaptogenesis in the Fetal Corpus Striatum, Globus Pallidus, and Substantia Nigra

Abstract

Synaptogenesis can be detected in tissue sections by immunoreactivity for synaptophysin, a synaptic vesicle glycoprotein that serves as a marker of synaptic maturation. Reactivity was prospectively studied postmortem in sections of the striatum, globus pallidus, and substantia nigra in 172 normal human fetuses and neonates of 6 to 41 weeks’ gestation. Caudate nucleus and putamen show patchy reactivity beginning at 13 weeks’ gestation around some intracapsular neurons; the pattern is well developed in all regions before midgestation. Near-uniform reactivity throughout the striatum is achieved by 34 weeks, but subtle patchiness is still perceived at term. The globus pallidus shows uniform reactivity without stria from 13 weeks and the substantia nigra from 9 weeks. Synaptic patchiness in the fetal corpus striatum appears to correspond to the “striosomes of Graybiel” that define adjacent neurotransmitter-rich and neurotransmitter-poor zones. Clinical correlation is proposed with dystonic postures and athetoid movements observed in normal preterm neonates of 26 to 32 weeks.