Characterization of immunofluorescent cyclic GMP-positive fibres in the central nervous system

The cyclic GMP immunofluorescent fibres in the rat central nervous system have been characterized as processes of fibrous astrocytes, on the basis of distribution and similarity to the localization of glial fibrillary acidic protein. The neuroglial localization of the nucleotide is discussed together with the surprising observation that these cyclic GMP positive fibres are absent from the central nervous system of the adult mouse.