The anatomical distribution and morphology of extraadrenal chromaffin tissue (abdominal paraganglia) in the dog

Abstract

The anatomical distribution, in situ, and morphology of extraadrenal chromaffin tissue in the retroperitoneum of dogs of various ages was studied by utilizing glutaraldehyde perfusion followed by glutaraldehyde/potassium dichromate immersion. This method of study produced a gross chromaffin reaction that clearly demonstrated abundant catecholamine-containing paraganglionic tissue. The procedure also provided excellent tissue preservation for subsequent light and electron microscopic study of the dichromate-traced organs. The largest chromaffin organ consistently occurred ventral and lateral to the abdominal aorta in the mid-retroperitoneum. Extensions of this body often reached the adrenal glands, but a specific continuity between intra- and extra-adrenal chromaffin tissues was not observed. Smaller organs, probably corresponding to the Organs of Zuckerkandl in the human, occurred around the inferior mesenteric artery. Light microscopy identified a parenchyma rich in epithelial cells exhibiting cytoplasmic vesicles and prominent nuclei and nucleoli. Connective tissue and numerous blood vessels delineated the chromaffin cells into groups. Electron microscopy showed cellular detail characteristic of chromaffin cells and confirmed the cytoplasmic presence of typical catecholamine granules. The majority of granules exhibited homogeneously dense cores. However, many others appeared less dense and displayed granular cores. This study provides evidence that extraadrenal chromaffin organs in dogs are voluminous, rich in catecholamine granules, and persist into adulthood.