Glial fibrillary acidic protein. A cellular marker of tanycytes in the mouse hypothalamus.

The differentiation of tanycytes during development of the mouse hypothalamus has been followed by immunohistochemistry with a GFA protein antiserum. Radially oriented processes of the tanycytes were stained with GFA antiserum in the ventral and the dorsal lining of the third ventricle in the mouse neonate and at later ages. Typical astrocytes in the hypothalamus could not be visualized before 16-20 days postnatally. These results indicate that tanycytes, which acquire their final position early in embryonic development, exhibit a structural feature of fully differentiated astrocytes early in postnatal development.