The role of cell and tissue interactions in the differentiation and development of the nervous system has been little investigated. Notwithstanding the spectacular domination of nervous tissue during the early stages of vertebrate embryogenesis, most of the factors governing morphological and functional differentiation of the various neuronal types are still obscure, and the origins of regional differences are poorly understood. The proven necessity of intimate spatial relationships between cells of some developing systems indicates that factors arising from cellular contacts are essential to full typespecific differentiation.2 The complexity of such requirements shifts with age or stage of development.3 Critical interactions and mutual contributions between different tissues, eg, epithelium and mesoderm, in early organogenesis are, moreover, similarly well documented although the chemical identity of the inductors is largely unknown.2,4
The cerebellum of the newborn mouse is extremely immature, showing little of the complex structure and cyto-architecture of
Allerand CD, Murray MR. Myelin Formation in Vitro: Endogeneous Influences on Cultures of Newborn Mouse Cerebellum. Arch Neurol. 1968;19(3):292–301. doi:10.1001/archneur.1968.00480030070007
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