Thiamine-like fibers in the monkey brain: an immunocytochemical study.

The distribution of thiamine-immunoreactive structures was studied in the brain of the monkey using an indirect immunoperoxidase technique. Fibers containing thiamine, but no thiamine-immunoreactive cell bodies, were found. The highest density of fibers containing thiamine was observed in the pulvinar nucleus and in the region extending from the pulvinar nucleus to the caudate nucleus. In the mesencephalon, immunoreactive fibers containing thiamine were only found at rostral level close to the medial lemniscus (at the mesencephalic-diencephalic junction). In the thalamus, the distribution of thiamine-immunoreactive structures was more widespread. Thus, immunoreactive fibers were found in nuclei close to the midline (centrum medianum/parafascicular complex), in the ventrolateral thalamus (medial geniculate nucleus, inferior pulvinar nucleus), and in the dorsolateral thalamus (lateral posterior nucleus, pulvinar nucleus). Finally, in the anterior commissure and in the cerebral cortex a low density immunoreactive fibers was visualized. Thus, in the brainstem, no immunoreactive structures were visualized in the medulla oblongata, pons, or in the medial-caudal mesencephalon, and no immunoreactive fibers were observed in the cerebellum, hypothalamus and in the basal ganglia. The present report describes the first visualization and the morphological characteristics (thick, smooth and short, medium or long in length) of the thiamine-immunoreactive fibers in the primate central nervous system using an antiserum directed against this vitamin. The distribution of thiamine-immunoreactive structures in the monkey brain suggests that this vitamin could be involved in several physiological mechanisms.

Riboflavin-like inmunoreactive fibers in the monkey brain.

Using an antiserum directed against the vitamin riboflavin, we studied the distribution of riboflavin-like immunoreactive structures in the monkey brain. In the mesencephalon, at the level of the mesencephalic-diencephalic junction, single riboflavin-like immunoreactive fibers were observed in its dorsal part, whereas a low density of immunoreactive fibers was found below the surface of the section and close to substantia nigra, and a high density was observed above the substantia nigra and close to the medial geniculate nucleus. In the thalamus, single riboflavin-like immunoreactive fibers were found in the ventral regions of the lateral posterior and the medial geniculate nuclei; a low density in the region located above the medial and lateral geniculate nuclei and a high density in the ventral part of the pulvinar nucleus and in the region extending from this latter to the caudate nucleus. Immunoreactive fibers were not observed in the medulla oblongata, pons, cerebellum, hypothalamus, basal ganglia and cerebral cortex. Moreover, no riboflavin-like immunoreactive cell bodies were observed in the monkey brain. The distribution of riboflavin-like immunoreactive fibers in the monkey suggests that this vitamin could be involved in several physiological mechanisms.

Folic acid in the monkey brain: an immunocytochemical study.

The present report describes the first visualization of folic acid-immunoreactive fibers in the mammalian central nervous system using a highly specific antiserum directed against this vitamin. The distribution of folic acid-immunoreactive structures was studied in the brainstem and thalamus of the monkey using an indirect immunoperoxidase technique. We observed fibers containing folic acid, but no folic acid-immunoreactive cell bodies were found. In the brainstem, no immunoreactive structures were visualized in the medulla oblongata, pons, or in the medial-caudal mesencephalon, since at this location immunoreactive fibers containing folic acid were only found at the rostral level in the dorsolateral mesencephalon (in the mesencephalic-diencephalic junction). In the thalamus, the distribution of folic acid-immunoreactive structures was more widespread. Thus, we found immunoreactive fibers in the midline, in nuclei close to the midline (dorsomedial nucleus, centrum medianum/parafascicular complex), in the ventral region of the thalamus (ventral posteroinferior nucleus, ventral posteromedial nucleus), in the ventrolateral thalamus (medial geniculate nucleus, lateral geniculate nucleus, inferior pulvinar nucleus) and in the dorsolateral thalamus (lateral posterior nucleus, pulvinar nucleus). The highest density of fibers containing folic acid was observed in the dorsolateral mesencephalon and in the pulvinar nucleus. The distribution of folic acid-immunoreactive structures in the monkey brain suggests that this vitamin could be involved in several mechanisms, such as visual, auditory, motor and somatosensorial functions.