Pansegmental primordial glycogen body in the spinal cord of postmetamorphic Pleurodeles waltlii (urodela).

Abstract

Light microscopical histochemistry and transmission electron microscopy have been used to identify large amounts of glycogen stored in the cytoplasm of specialized astroglial cells in the spinal cord of ribbed newts. These cells are found throughout the whole length of the cord. They are located in the dorsolateral lateral aspects of the periependymal stratum, and according to their cytological characteristics they have been considered as glycogenic astroglia. Massive glycogen inclusions occupy a subsurface position mainly in those cell processes that do not project outside the central field, which form a tight packed territory surrounding the ependyma. Topological, histological, histochemical and cytological similarities are revealed between glycogenic astroglia and specialized astroglial cells found in the primordial lumbar avian glycogen body, as well as in the brachial glycogen body of the chick spinal cord. The similarities strongly suggest the homology between these structures. The pansegmental distribution found in the newt could be a clue for understanding the physiological role of such a structure.