FOETAL SHEEP - MORPHOGENESIS OF NERVOUS SYSTEM AND HISTOCHEMICAL ASPECTS OF MYELINATION

The development of the central nervous system of the sheep foetus with particular reference to myelin forming cells and myelination has been studied by morphological and histochemical methods. The development of the spinal cord resembles that described for other species and broadly similar patterns of development have been found for the other major regions. Differentiation of definitive cell types is marked by the appearance of cytochrome oxidase activity in their cytoplasm. In gray matter strong cytochrome oxidase activity persists into post‐natal life whereas in white matter activity declines following commencement of myelination. Lipids having the histochemical reactions of myelin first appear in a particular region as the capillary circulation of that region develops. It is suggested that phospholipid elements of perivascular lipid may be rapidly incorporated into the developing myelin sheath whilst galactolipids from the same location are more slowly utilized. The implications of the findings are discussed. Copyright © 1969 The Wistar Institute of Anatomy and Biology