Summary
Serial sections (15 μm, 120 μm, and 400 μm) of nine brain stems treated with a combined lipofuscin pigment-Nissl stain were examined in order to delineate the three-dimensional conformation and subdivisions as well as the neuronal types of the human oral raphe system. Characteristic lipofuscin deposits within the somata of various cell types facilitated the demarcation of the oral raphe nuclei from surrounding structures. The dorsal, central, and linear raphe nuclei, e.g. the major subdivisions of the oral raphe system, share common traits as far as neuronal composition and pigmentation is concerned. The interfascicular subnucleus, the dorsofascicular subnucleus, and the intercalate subnucleus are minor subdivisions of the dorsal raphe nucleus. The intercalate one cannot be differentiated from surrounding areas in preparations solely stained for Nissl-material, while it can facilely be identified in combined pigment-Nissl preparations by virtue of differences in the pigmentation pattern. Our architectonical concept of the oral raphe system is in good accordance with the one derived from immunocytochemical investigations of serotonin-containing neurons in the human brain stem. Furthermore, five main neuronal types are described which constitute the oral raphe nuclei. They have been differentiated according to their characteristics as seen in combined pigment-Nissl preparations. I) Large ovoid to polygonal neurons with densely packed and intensely stained pigment granules. II) Similarily featured cells displaying dust-fine and faintly stained pigment granules. III) Medium-sized, ovoid to polygonal neurons with loosely distributed, small pigment granules. IV) Small ovoid neurons devoid of pigment or with only few, intensely stained granules. V) Small spindleshaped nerve cells with various amounts of intensely stained pigment granules. The morphometrical examination has revealed considerable overlapping in size between types I and II. A fact that would not allow a distinction in preparations solely stained for Nissl-material.
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Ohm, T.G., Heilmann, R. & Braak, H. The human oral raphe system. Anat Embryol 180, 37–43 (1989). https://doi.org/10.1007/BF00321898
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DOI: https://doi.org/10.1007/BF00321898