Catecholamine innervation of the forebrain in the bull frog, Rana catesbiana.

The innervation of forebrain catecholamine (CA) were experimentally investigated with use of sensitive fluorescence method of glyoxylic acid formaldehyde in the brain of the bull frog, Rana catesbiana. The CA of the olfactory bulb is supplied by CA neurons situated in olfactory bulb. And CA neurons in the hypothalamus contribute the main source for the forebrain CA except olfactory bulb. The hypothalamic CA neurons also give rise to long descending axons to innervate the brain stem. Judging from their anatomical aspects it seems that the structure homologous to mammalian nigro-neostriatal dopamine or mesolimbic dopamine system is not present in amphibian brain.