Glial filaments

Glial filaments Mr = 50,000 Some glial cells, e.g., astrocytes... 

Intermediate filaments (10 nm) are intermediate in diameter between microtubules (25 nm) and actin filaments (7 nm). Intermediate filaments are classified into five groups cytokeratin, desmin, vimentin, neural, and glial filaments (for review, see Lazarides, 1980). In skeletal muscle, there are both desmin and vimentin filaments. 

Tremblay GF, Lee VMY, Trojanowski JQ. Expression of vimentin, glial filament, and neurofilament proteins in primitive childhood brain tumors A comparative immunoblot and immunoperoxidase study. Acta Neuropathol. 1985 68 239-244. 

Trojanowski JQ, Lee VMY, Schlaepfer WW. An immunohistochemical study of central and peripheral nervous system tumors with monoclonal antibodies against neurofilaments and glial filaments. Hum Pathol. 1984 15 248-257. 

Trojanowski JQ. Neurofilament and glial filament proteins. In Wick MR, Siegal GP, eds. Monoclonal antibodies in diagnostic immunohistochemistry. New York Marcel Dekker 1988 115-146. 

Although these tumors are pleomorphic, most nuclei lack sharp angulations, and the giant cells are not crowded. These cells may contain glial filaments variably positive for GFAP (see Fig. 20.16A). 

Cavitary gliosis Wall of gliosis GFAP in glial filaments (-i-) S-100 (-I-) Cerebrum CNS... 

Fig. 8. Electron micrograpn aemonstrating the formation of intermembranous electron dense junctions (thick arrows) between neuronal processes (NP) and astrocytic membrane. GF glial filaments.

Tissue-specific intermediate filaments have been classified into vimentin filaments, glial filaments, neurofilaments, desmin filaments and cytokeratin filaments. Although each type of filament is composed of a different protein, the various proteins demonstrate remarkable sequence homology. Their functions are unknown. There are at least nine different proteins associated with intermediate filaments. 

---