Observations on the anatomy and amine histochemistry of the nerves and ganglia which supply the pelvic viscera and on the associated chromaffin tissue in the guinea-pig

Summary The organs of the lower abdominal and pelvic regions of the guinea-pig receive nerves from the inferior mesenteric ganglia and pelvic plexuses. The inferior mesenteric ganglia connect with the sympathetic chains, the superior mesenteric ganglia, the pelvic plexuses via the hypogastric nerves, and with the gut. Each pelvic plexus consists of anterior and posterior parts which send filaments to the internal generative organs and to the rectum, internal anal sphincter and other pelvic organs. The pelvic nerves enter the posterior plexuses, which also receive rami from the sacral sympathetic chains. The adrenergic neurons of the pelvic plexuses are monopolar, do not have dendrites and are supplied by few varicose adrenergic axons. Nearly all the nerves contain adrenergic fibres. After exposure to formaldehyde vapour the chromaffin cells appear brightly fluorescent with one or two long, often varicose, processes. Most of the chromaffin cells are in Zuckerkandl's organ or in chromaffin bodies associated with the inferior mesenteric ganglia. Groups of chromaffin cells are found along the hypogastric nerves and in the pelvic plexuses; they become smaller and fewer as regions more posterior to Zuckerkandl's organ are approached.This work was supported by grants from the Australian Research Grants Committee and the National Health and Medical Research Council. We thank Professor G. Burnstock for his generous support.