[Morphology of glial cells in the lower olivary complex of the pigeon (Columba livia). I. Astrocytes].

The morphologic peculiarities of astrocytes in the lower olivary complex (LOC of a pigeon were examined at light and electron microscopic level. Usage of histological technique established the presence of three varieties: fibrous, real protoplasmic and covered type of astrocytes. In LOC of a pigeon most of astrocytes, observed by the electron microscope, possessed in their cytoplasm bunches of filaments, which passed and proceeded along side to astrocytic arborizations parallelly. Other type of arborizations were the so-called astrocytic plates, which were frequently arranged at layers and embraced the elements of the neuropappila under the form of capsules. Multiple desmosomo-like and gap junctions were encountered between adjoining astrocytic membranes. Heterogenous astro-oligodendrocytic gap junctions were observed as well. The functional significance of these glial cells and their probable role in neuronal metabolism is discussed on the basis of a comparative analysis of the structural and ultrastructural characteristics of astrocytes in LOC of a pigeon and in various species of mammals.