Nuclei of the human raphe

Abstract

Along the raphe of the brain stem, a series of small neuronal groups can be observed in the medulla oblongata, the pons and the mesencephalon. The neurons located in and adjacent to the raphe are considered to produce mainly serotonin (5-HT). The groups of nuclei containing 5-HT were first reported in experimental animals in the early 1960s¹⁾. The presence of such nuclei, however, has not yet been brought to light in the human brainstem except the few atlases^{2, 3)}, although in several neuroanatomy textbooks⁴⁾, extrapolated data are shown in the form of drawings as if they were the data from the human brain. The aim of this study is to present microscopic photos of such raphe nuclei made from serial sections of the human brainstem, and to clarify the differences between findings in human and textbook drawings from animal data.