MYELINATION OF THE OVINE CNS WITH SPECIAL REFERENCE TO BORDER DISEASE. I. QUALITATIVE ASPECTS*

Abstract

Myelination of the ovine CNS with special reference to Border disease. I. qualitative aspectsA detailed qualitative study of the process of myelination in the dorsal funiculus of a series of ovine fetuses of known gestational age has been made and compared with age‐matched fetuses affected with experimental Border disease (hypomyelino‐genesis congenita). The fetuses, obtained by hysterectomy, were perfused with glutaraldehyde and examined by light and electron microscopy. It was found that the process of myelination in the normal fetal sheep is similar to that in other mammalian species. In Border disease the irregularities of axon profile which occur briefly during their normal premyelination enlargement tend not to resolve. This change is associated with slow and inadequate myelination and a large increase in and persistence of Type III glial cells. These cells contain hydrophilic lipids, butshow little evidence of phagocytosis.