Major cell types of the central nervous system comprise neurons, glial cells 
(astrocytes, oligodendrocytes, ependymal cells, and microglia), choroid plexus 
cells, cells related to blood vessels and coverings. These cells show a wide 
range of reactions to various noxious agents, which can be detected in routine 
stainings. Some of these reactions are nonspecific to different injuries; 
however some, such as the appearance of inclusion bodies, can be highly 
disease-specific. Immunohistochemical markers are widely used in neuropathologic 
diagnostic practice and help to understand the pathogenesis of diseases. The 
most widely used neuronal markers comprise phosphorylated and nonphosphorylated 
neurofilaments, microtubule-associated protein-2, NeuN, or synaptic markers such 
as synaptophysin. The best antibody for the detection of astrocytes is anti-GFAP 
(glial fibrillar acidic protein); however, to support a glial origin, S100 or 
vimentin is also used in the diagnostic practice. Further astroglial markers 
include connexin-43, excitatory amino acid transporters, aquaporin-4, heat shock 
protein Hsp27, and α-B-crystallin. Depending whether the tissue is fixed or 
nonfixed, different oligodendroglial markers are available, such as myelin basic 
protein, myelin oligodendrocyte glycoprotein, myelin-associated glycoprotein, 
proteolipid protein, Olig2, NG2, 2' 3'-cyclic nucleotide 3-phosphodiesterase 
(CNPase), and tubulin polymerization-promoting protein/p25 alpha (TPPP/p25). A 
wide range of microglia functions is recognized. Apart from a role in 
immune-mediated disorders, inflammation, and response to injury, microglia are 
important during the development and aging of the brain. The best markers 
include the clone CR3/43, Iba1, and CD68. Evaluation of cell reactions is the 
first step in the diagnostic procedure.