Glutamine Synthetase in the Cells of the Developing Rat Spinal Cord

The formation of the glutamatergic system of the spinal cord is intensively studied, however, there are hardly any studies devoted to the investigation of the dynamics of the formation of glutamine synthetase-containing structures that protect the nerve cells of the embryonic spinal cord from the toxic effects of glutamate. In this paper, the localization, distribution, and morphological features of rat spinal cord (SC) cells expressing glutamine synthetase (GS) in the embryonic and early postnatal period were studied using immunohistochemical methods. It was found that the first GS-containing cells are identified in the ventral part of the ependymal layer of the formed SC during the beginning of gliogenesis, on the 15th day of embryonic development. After 1 day, cells expressing this enzyme are also present in the mantle layer of the SC. In this study, it was shown for the first time that a part of the boundary cap cells located in the transition zone between the SC and the peripheral nervous system synthesizes glutamine synthetase. The present study allowed us to determine the dynamics of the formation of GS-containing glial cells of the embryonic spinal cord and to assume the functional significance of such cells in embryogenesis.