An immunohistochemical study of the topography and cellular localization of three neural proteins in the sheep nervous system.

The peroxidase-anti-peroxidase (PAP) method was used to determine the topography and cellular localization of glial fibrillary acidic protein (GFAP), myelin basic protein (MBP) and carbonic anhydrase II (CAII) in the central nervous system (CNS), dorsal root ganglia and dorsal and ventral spinal nerve roots of the sheep. Parallel studies of mouse brain provided comparative data. Several fixatives were compared for their relative merits in preserving marker protein expression: GFAP was well preserved irrespective of the fixative employed; MBP was best preserved in formal sublimate and CAII was best preserved in Carnoy's fluid. In sheep, GFAP expression was seen in protoplasmic and fibrous astrocytes, Bergmann glial cells, a proportion of ependymal cells, amphicytes of spinal ganglia and in a proportion of presumed Schwann cells of dorsal and ventral spinal nerve roots. MBP expression was seen in mature and developing myelin sheaths of the central nervous system and in the cytoplasm of sparse myelinating oligodendroglia of the sub-cortical white matter of the cerebrum. CAII expression was seen in choroid plexus epithelium in all ages of sheep studied and, in a young lamb and an adult sheep, in glia and neuropil of ventral horn grey matter of the spinal cord and in the cytoplasm of white matter glia, presumed fibrous astrocytes, throughout the CNS. Compared with sheep brain, mouse brain showed the following differences in marker protein localization. GFAP was weakly expressed by protoplasmic astrocytes and not expressed in ependyma, oligodendroglia expressing intracytoplasmic MBP were frequent and widespread in neonatal mouse brain, CAII was expressed in myelin and oligodendroglia.(ABSTRACT TRUNCATED AT 250 WORDS)