Dopaminergic periglomerular cells in the turtle olfactory bulb.

With the indirect immunofluorescence technique using antisera to three catecholamine synthesizing enzymes, labeled periglomerular cells as well as their intraglomerular processes were observed in the turtle olfactory bulb. These cells could also be recognized in the EPL and the glomerular layer. Unlabeled periglomerular cells were also seen. Thick labeled processes (presumably dendrites) entered the glomerular neuropil, and there formed a dense network, with numerous terminal varicosities. These results support the existence of a unique, homologous dopaminergic subdivision of the periglomerular interneurons throughout classes of vertebrates. In addition, a second type of weakly tyrosine hydroxylase immunoreactive neurons was observed in the outer part of the granule layer. Dopamine beta-hydroxylase positive fibers were seen in the granule, mitral and external plexiform layers.