Similarities and differences in supporting and chromaffin cells in the mammalian adrenal medullae: An immunohistochemical study

Backgrounds: The adrenal medulla is a typical paraganglion, having the same origin as the sympathetic ganglia, and contains at least two types of parenchymal cells: chromaffin cells and supporting cells. We previously reported that the extent of cellular association of chromaffin cells with supporting cells was remarkably higher in noradrenaline (NA)‐than in adrenaline (A)‐cell regions in the adrenal medullae of the rat and pig. Methods Cryostat sections of adrenal medullae of nine mammalian species fixed with Zamboni fluid for 24 h were immunostained by ABC methods using antisera to S‐100 protein and PNMT. Results The distribution patterns of A and NA cells in the adrenal medullae were classified into four types. In the chipmunk and rabbit, adrenomedullary chromaffin cells consisted of A cells. S‐100‐immunoreactive cells were present more frequently in NA‐ than in A‐cell regions in seven species (rat, golden hamster, cat, dog, pig, ox, and horse). These cells sent out cytoplasmic processes and formed a network by immunoreactive elements among NA cells. The cell‐association patterns of S‐100‐positive cells with NA cell were classified into three types. In A‐cell regions, only a few S‐100‐positive cells were seen in most of the species, although the frequency of S‐100‐labeled cells were exceptionally high in the horse. Conclusion The close association of supporting cells with NA cells was commonly found in the adrenal medulla in many mammalian species, irrespective of the proportions and distribution patterns of A cells and NA cells. On the other hand, species differences existed in details of the cellular association between supporting cells and NA cells. © 1996 Wiley‐Liss, Inc.