Monoclonal antibody to glial fibrillary acidic protein reveals a parcellation of individual barrels in the early postnatal mouse somatosensory cortex.

The relative dispositions of cells in immature and mature mouse barrel field cortices that bind antibody to glial fibrillary acidic protein (GFAP) were examined and photographed under the light microscope. Light micrographs demonstrate that radially oriented glial cells are present in the barrel field of postnatal day 6 cortices and that they are located predominantly within the presumptive barrel sides and/or septae, thus sharply delineating individual barrels from each other. The relative dispositions of radial glial fibers observed at this time implicate glia in development of topographic order during early postnatal development of the somatosensory cortex. In contrast, no such delineation could be detected in the cortices of more mature mice, because GFAP-positive astrocytes are present throughout the barrel field and are not confined to barrel sides. This ephemeral nature of the GFAP-delineated barrel field is of interest with respect to the recently reported ephemeral lectin-delineated barrel field.