Appearance of diaminobenzidine-staining glial cells in the rat CNS: an ontogenetic histochemical study.

The postnatal appearance of diaminobenzidine (DAB)-staining glial cells was studied in certain regions of the rat central nervous system. DAB-positive cells appeared in the hypothalamus, the nucleus of the solitary tract and the most superficial laminae of the spinal dorsal horn on the 7th, 8th and 14th postnatal day, respectively. The number and staining intensity of these DAB-positive cells progressively increased and reached the adult levels at the end of the third postnatal week. Glial staining is likely to result from a non-enzymatic oxidation of DAB, since it was resistant to heat pretreatment, but was abolished if hydrogen peroxide was omitted from the incubation medium. The present results reveal that a particular population of glial cells exhibit a characteristic developmental change which can be detected by means of peroxidase histochemistry. The close topographical relationship is suggestive of a functional association between capsaicin-sensitive primary afferents and DAB-positive glial cells.