Resumen de Postnatal development of the rat cochlear nuclei. Qualitative study with the glial markers GFAP and vimentin.

P. Gil-Loyzaga, F. J. Valderrama-Canales

• The cochlear nuclei are the first central step in the ascending auditory pathway. Studies on the development of the cochlear nuclei have been devoted to the histogenesis, neuronal maturation and migration, development and setting up of projections, and development of neurotransmitters. During postnatal maturation of the cochlear nuclei, neurons migrate to their definitive positions and the connections of the nuclear complex are established and refined. However, in spite of the fundamental role of the glia during the morphogenesis of the central nervous system, little attention has been paid to the presence and function of the astroglial cells within the cochlear nuclei. In light of this, here we investigated the presence, morphology and temporal patterns of the appearance of the astroglial cells of the cochlear nuclei. To identify the glial cells, monoclonal antibodies were used to detect glial fibrillary acidic protein and vimentin. The immature intermediate filament cytoskeleton of astrocytes it is made up of vimentin, and that of radial glial cells, and, as development proceeds, glial fibrillary acidic protein constitutes the intermediate filament cytoskeleton in mature astrocytes. Our study revealed the presence of radial glial cells and astrocytes within the cochlear nuclei along postnatal development. A reciprocal relationship in the distribution of glial fibrillary acidic protein and vimentin during maturation of the cochlear nuclear complex is reported. The morphology, temporal patterns of appearance, and maturation of glial cells are discussed in relation to the morphogenesis and maturation of the cochlear nuclei, placing the possible role of radial glia in the migration of cochlear cells and in the guidance of the axons to their functional targets.