Abstract
For the investigation of t h e morphology and architectonics of the glial cells in the chicken brain and spinal cord, the author observed first the glial cells in the optic tract, where no nerve cell bodies occur, staining with hematoxylin and other routine stainings for the nuclei of glial cells and with various kinds of silver impregnation methods for the cell body and processes of the glial cells.
The morphological characteristics of glial cells in th e chicken optic tract, which were stained with silver impregnation methods, were classified into four types of fibrous astrocyte, oligodendroglia, microglia (lamellar form) and unknown type of glial cells as in the white matter of mammals.
Though the types of glial cells which were stained satisfactorily were more or less different according to kinds of silver impregnation methods employed, the characteristics of silver impregnated images of each type of glial cells scarcely showed a difference.
According to the nuclear structures of glial cells, they were classified into four types. The three types were considered to correspond to astrocyte, oligodendroglia and microglia respectively which were seen in silver impregnated materials, and the fourth type of glial nuclei was small and chromatin-rich, and might be immature glial cells as described by Smart and Leblond (1961). In the optic tract the glial cells consisted chiefly of oligodendroglia (so-called interfascicular glia) and they were arranged in various length of rows between nerve fibers. The glial cells were also found along small blood vessel walls in a long line in the stratum opticum or in a short line in the optic chiasm and its neighbouring region. In the optic chiasm and its neighbouring region the numerous glial cells were occasionally found to form clusters around the small blood vessels. These groups consisted of numerous oligodendroglia and a few of astrocytes and microglia.
