Immunocytochemical demonstration of astrocytes and microglia in the whale brain

Whale brains have attracted the attention of neuroscientists but there are only sparse studies on whale glial cells. Here we report on immunolabeling of astrocytes by antibodies to glial fibrillary acidic protein (GFAP) or protein S-100 beta (both by the streptavidin/biotin technique), and labeling of microglial cells by Griffonia simplicifolia agglutinin (GSA I-B4, coupled to horseradish peroxidase), in the neocortex of a harbour porpoise Phocoena phocoena L. Many subpial and perivascular astrocytes were stained; they differed greatly in thickness and length of their processes. Subpial astrocytes were coarse with a few stout stem processes, whereas perivascular astrocytes deeper in the brain had many long and slender processes. Additionally, some long radial astrocytes were observed. Microglia were labeled throughout the brain, and showed similar features as 'resting' (ramified) microglia in the brain of other mammals.