LH-RH Neuron System of the Newt by Immunohistochemical Study

Abstract

The location of LH-RH [luteinizing hormone releasing hormone] producing neurons, the pathways and terminal distribution of their fibers in the newt C. pyrrhogaster were studied immunohistochemically. The LH-RH positive perikarya are located in the nucleus of the diagonal band of Broca and the medial septal nucleus. No LH-RH immunoreactive neuronal perikarya could be detected in the diencephalon. The pathways of fibers originating from the LH-RH reactive neurons were classified into 3 groups: the first project to the median eminence, the second to the olfactory bulb and the third to the habenular nucleus. The latter 2 pathways are extrahypothalamic, similar to those in mammals. These observations are briefly discussed and compared with those in other amphibian and mammalian species.