[Ultrastructure of the proliferation of astrocytes and microglia]

Glial cell proliferation was studied during axonal reaction of hypoglossal nerve, and around stab wound in the brain cortex of the rat. The cytoplasm and chromosomes of astroglial mitoses were pale. Lipid droplets, few sparse dense bodies with heterogenous structure were present in the cytoplasm. The mitotic astrocytes had irregular outlines. The ultrastructure of "light microglial" cells was described; it was found that these cells divided and gave rise to microglial cells. The cytoplasm and the chromosomes of microglial mitoses were dense; the cytoplasm contained always groups of dense bodies and lipfuscine granules. The outlines of mitotic microglial cells were more regular.