Somatostatin in the brain of the turtle Testudo hermanni Gmelin. An immunohistochemical mapping study.

An immunohistochemical mapping study in the brain and upper spinal cord of the turtle Testudo hermanni Gmelin revealed a wide distribution of somatostatin perikarya and fibres. Within the telencephalon, somatostatin perikarya are present in the anterior olfactory nucleus, in the medial, dorsomedial and dorsal cortex, in the pallial thickening, in the piriform cortex, paleostriatum augmentatum, in the dorsoventricular ridge, core nucleus of the dorsoventricular ridge, in area c and d, and in the amygdala. In the diencephalon, the periventricular nucleus of the hypothalamus contains many somatostatin perikarya. Cerebrospinal fluid contacting somatostatin perikarya of the infundibular nucleus terminate with club-like endings in the ventricular cavity. Some somatostatin perikarya are present in the nu. reuniens of the thalamus and in the lateral habenular nucleus of the epithalamus. Within the mesencephalon somatostatin perikarya are located in the interpeduncular nucleus, area tegmentalis ventralis and in the nu. reticularis isthmi. In the rhombencephalon, somatostatin perikarya are encountered in the nu. raphe superior, nu. reticularis magnus, periventricular grey matter, bed nucleus of the fasciculus longitudinalis medialis and in the nu. solitarius-vagus complex. Somatostatin fibres form a circular band in the olfactory bulb. In the telencephalon, dense aggregations of somatostatin fibres are present in the anterior olfactory nucleus, in the pallial thickening, in the parahippocampal gyrus, cortex medialis, dorsomedialis, dorsalis and piriformis, in the dorsal ventricular ridge, paleostriatum augmentatum, area c and d, in the septum, nu. diagonalis of Broca, in the amygdala and in the anterior commissure. In the diencephalon, somatostatin fibres terminate at the vessels of the organum vasculosum of the lamina terminalis. A dense band of somatostatin fibres surrounds the rostral third ventricle. Somatostatin fibres terminate in the infundibulum at portal capillaries, and in the neural lobe. Somatostatin fibres are found in the periventricular, ventromedial and lateral nucleus of the hypothalamus. In the thalamus, the area triangularis, the dorsomedial and dorsolateral area and the nu. reuniens contain somatostatin fibres. Somatostatin fibres are very dense in the lateral habenular nucleus. At the mesencephalic level, somatostatin fibres are found in the pretectal nucleus, in the deep layers of the tectum, in the nu. tori semicircularis lateralis, in the interpeduncular nucleus, area tegmentalis ventralis, nu. ruber, substantia nigra and periventricular grey.(ABSTRACT TRUNCATED AT 400 WORDS)