Median nerve neurosecretory cells in the abdominal ganglia of the cockroach, Periplaneta americana

Three groups of cells in the abdominal ganglia of Periplaneta americana have their endings in median nerve neurohaemal organs. There is some evidence that these endings are the same as those containing electron transparent vesicles in electron micrographs. The cell bodies of the median nerve cells are located in the midlines of ganglia 1 to 5. They do not exhibit any special staining reactions, but they do become labelled in animals injected with tritiated dopamine. Possible implications of this labelling are discussed.