G. Bodega et al., EPENDYMA - PHYLOGENETIC EVOLUTION OF GLIAL FIBRILLARY ACIDIC PROTEIN (GFAP) AND VIMENTIN EXPRESSION IN VERTEBRATE SPINAL-CORD, Histochemistry, 102(2), 1994, pp. 113-122
The phylogenetic evolution was studied of both glial fibrillary acidic
protein (GFAP) and vimentin expression in the ependyma of the adult v
ertebrate spinal cord. Eleven species from different vertebrate groups
were examined using different fixatives and fixation procedures to de
monstrate any differences in immunoreactivity. GFAP expression in the
ependymal cells showed a clear inverse relation with phylogenetic evol
ution because it was more elevated in lower than in higher vertebrates
. GFAP positive cells can be ependymocytes and tanycytes, although dep
ending on their structural characteristics and distribution, the scarc
e GFAP positive ependymal cells in higher vertebrates may be tanycytes
. Ependymal vimentin expression showed a species-dependent pattern ins
tead of a phylogenetic pattern of expression. Vimentin positive ependy
mal cells were only found in fish and rats; in fish, they were tanycyt
es and were quite scarce, with only one or two cells per section being
immunostained. However, in the rat spinal cord, all the ependymocytes
showed positive immunostaining for vimentin. The importance of the im
munohistochemical procedure, the cellular nature of GFAP positive epen
dymal cells and the relationship between tanycytes and ependymocytes a
re discussed, as well as GFAP and vimentin expression.