Topographical localization of substance P in the human post-mortem brainstem. An immunohistochemical study in the newborn and adult tissue.

The localization of substance P-immunoreactive nervous structures in the newborn and adult human brainstem is studied by the indirect immunofluorescence technique of Coons and collaborators. Substance P-containing perikarya, nerve fibres and terminals are widely and unevenly distributed in several areas of the human brainstem, with a location similar to that described in other mammals; however, some remarkable differences are detectable, which speak in favour of the existence of species differences. For example, in the human brain there is a dense plexus of substance P-immunoreactive fibres in the cuneate fasciculus. The use of the newborn tissue is very helpful in the detection of the immunoreactive neuronal cell bodies. The comparative study of the newborn and the adult tissue reveals that the distribution of the substance P-like immunoreactivity changes in man during ontogeny and results in a more complete map of the substance P-containing neuron system.