Histochemical and ultrastructural features of neuronal pigment in some encephalic nuclei of ruminants

Neuronal pigment in red nucleus, locus coeruleus and substantia nigra from cattle, sheep and goat was examined with the aid of light and electron microscopy. In the red nucleus and locus coeruleus neurons of all the species examined the pigment shows the histochemical and ultrastructural features typical of lipofuscins. The ultrastructural observations indicated that the morphology of pigment granules is related to age and permitted identification of various stages of pigment evolution, which suggested a lysosomal origin of the pigment bodies. In bovine and sheep the substantia nigra is very reduced and contains no detectable pigment; while in goat, some neurons appear to contain discrete amounts of neuromelanin. Ultrastructurally this kind of pigment appears characterized by the features of a lipofuscin-like granule which stores highly electron dense material identifiable as melanin.