Origin of the avian glycogen body. II. Observations in support of a glial nature in the chick embryo.

Stem cells of the glycogen body in chick embryos at 7-8 days of incubation (stages 31-34) were studied by light microscopy autoradiography, immunocytochemistry, and following induced spina bifida to discern their nature and origin. Glycogen cells displayed the presence of glial fibrillar acid protein and vimentin at the time of their appearance at 7-8 days of incubation (stages 31-34). Displayed also were indications of DNA synthesis by thymidine incorporation during that period of development. Observations suggest that glycogen body cells are glial in nature, possibly radial glia which arise from neuroepithelium that comprises the ependyma and roof plate of the avian lumbosacral spinal cord.