Distribution of corticotropin-releasing factor immunoreactive neurons in the brain of the tigerfrog, Rana tigrina.

The distribution of immunoreactive (ir) neurons containing corticotropin-releasing factor (CRF) is described in the brain of the tigerfrog, Rana tigrina. The olfactory bulb, medial pallium, nucleus of the diagonal band of Broca and medial area of the amygdala of the telencephalon showed ir-CRF perikarya. The anterior and ventromedial thalamic nuclei, and the magnocellular nucleus preopticus (NPO) revealed several ir cells; a few NPO neurons were cerebrospinal fluid contacting in nature. The nucleus hypothalamicus ventromedialis contained a few cells, but the nucleus infundibularis ventralis of the infundibulum revealed several diffusely distributed perikarya. Individual ir-CRF perikarya were visualized in the optic tectum and interpeduncular nucleus. Extensive fiber terminals were present in the median eminence, but no fibers were discerned either in the neural lobe or in the pituitary gland.