Maturation of the central nervous system: comparison of equine and other species.

This review covers the development and maturation of the cerebellum of the horse and compares this developmental sequence with that of man, mouse and chicken. These comparisons attempt to correlate morphological and neurochemical features, developmental time and functional performance necessary for survival at birth. Although there is great disparity between these 3 species, the basic anatomical structures of the cerebellum are present as are specific cellular groups, synapses and neurochemical markers. In addition to this structural homogeneity, other attributes of the cerebellum are its easily identified cellular populations and its well ordered pattern of growth and differentiation. The cerebella of the developing chick and mouse have been studied in great detail as they are amenable to experimental manipulations. The pattern of cellular differentiation appears to be reproducible from species to species and differs primarily as it relates to gestational age and functional requirements at birth. For instance, most of the large neurones of the cerebellar cortex differentiate early with small neurones and neuroglia differentiating later. Neurogenesis of the cerebellar cortex is fairly complete in the newborn foal and chick hatchling, but not in the human or rodent newborn.