The abdominal perisympathetic neurohemal organs of the cockroach Periplaneta americana: Innervation revealed by cobalt chloride diffusion

By retrogradely diffusing Co²⁺ through the two perisympathetic organs associated with the transverse nerve of the third abdominal ganglion and subsequently precipitating the sulfide, four groups of neuron somata in that ganglion and two somata in the second abdominal ganglion are revealed. The four groups in the third abdominal ganglion occur at various levels adjacent to the midsaggital plane, and there are 8 to 16 neurons in each group. Comparable numbers of putative neurosecretory cells, with granules that are paraldehyde fuchsin and azocarmine positive, are located in most of these regions. Axons containing granules with these staining characteristics are also present in the perisympathetic organs. It is suggested that the granules are secretory products of the median neurons. The locations of the cell bodies, their sizes, and some of the intraganglionic pathways of their processes are described.