Development of the glycogen body of the Japanese quail, Coturnix japonica: II. Observations of electron microscopy.

Transmission electron microscopic observations of the relationships of the cells of the glycogen body and those of nervous tissue in the lumbosacral spinal cord show that one day after hatching, glycogen cells at the lateral margins of the glycogen body lie in close association with elements of the neuropil in the adjacent spinal cord. Glycogen cells and their processes appear to extend into the neuropil, where they contact other glycogen cells, blood vessels, neurons, and neuroglia. Junctional complexes and synapses occur among glycogen cells, astrocytes, and oligodendrocytes. Other indications of specialized activities were surmised by the presence of annulate lamellae in continuity with extensive arrays of smooth endoplasmic reticulum in several glycogen cells. These observations enhance our earlier views that cells of the avian glycogen body are metabolically active in the synthesis and degradation of glycogen for neuronal support and myelination in the central nervous system.