| Abstract: | Through studies of the spinal cord in a large series of the developmental stages of embryos, infant and adult house shrews (Suncus murinus), the central canal provided with ependymal cells was, using the light and electron microscopes, observed to disappear. The canal was obliterated completely from the level of the area postrema to the end of the spinal cord in the infant and adult animals and remained unreformed, the cause being entirely due to spontaneous cell death of ependymal cells lining the central canal during days 22 of gestation to 5 d after birth. Cell degeneration was marked by an increase in electron density of the cytoplasm, lysosomes prominent increase in number, and in later stages, by necrotic fragmentation of ependymal cells, which fragments were phagocytized and digested by macrophages, and microglias were observed in the empty spaces. |
