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The immunohistochemical expression of glial fibrillary acidic protein (GFAP) and vimentin (VIM) was studied in reactive astrocytes of the rat cerebral cortex 5 days after a brain injury. Seriated Epon semithin sections were immunostained alternatively for GFAP or VIM. Thereafter, both antigens were detected in consecutive sections of the same cell. Bordering the wound, an inner reactive glial layer 300–350 μm thick, showed positive astrocytes with the two immunohistochemical techniques. In this layer, about 60% of the GFAP positive astrocytes were also positive for VIM. Outside the inner layer, only GFAP positive astrocytes could be found.

The localization of vimentin (VIM) and glial fibrillary acidic protein (GFAP) was studied immunohistochemically in adult rat optic nerve. Consecutive Epon semithin tissue sections were immunostained respectively for VIM or GFAP. With this method, both antigens were detected in consecutive sections of the same cell. According to our results, most astrocytes in the adult rat optic nerve showed coexpression of VIM and GFAP.

Sympathetic nerve fibers arising from the superior cervical ganglia are the main innervation of the rat pineal gland. Since most organs innervated by these ganglia contain nerve growth factor (NGF), the hypothetical existence of NGF in the pineal gland was investigated. The peroxidase anti-peroxidase technique was applied for the immunohistochemical demonstration of NGF using a polyclonal antiserum on Bouin-fixed, paraffin-embedded pineal glands from adult, young and 6-hydroxydopamine (6-OHDA)-treated rats. Few immunopositive cells were observed in the adult pineal gland. A more conspicuous population of immunoreactive cells was noted in young animals (20-45 days old), especially in those chemically denervated with 6-OHDA. NGF immunoreactive cells displayed a stellate shape resembling the interstitial or glial cells previously described in the rat pineal gland. Since NGF plays a trophic effect on sympathetic neurons during development and adulthood, we postulate that its presence in the pineal gland may exert a trophic role on its sympathetic innervation.