The central nervous system location of neurochemicals that are widely distributed among extant animals may give us clues to changes that occurred in the brains of these animals during evolution. We have been studying the brains of cartilaginous…
We examined the distribution of immunoreactivity to serotonin (5-HT), leu-enkephalin (LENK), tyrosine-hydroxylase (TH), and substance P (SP) within the primary visceral sensory region of cartilaginous fish. Two genera of sharks, Squalus and…
In previous studies on reptiles and elasmobranchs, we determined that some reticular groups are either absent or may be displaced compared to their locations in mammals. For example, nucleus raphe dorsalis, the largest serotoninergic cell group in…
