SIMILARITIES AND DIFFERENCES IN SUPPORTING AND CHROMAFFIN CELLS IN THE MAMMALIAN ADRENAL MEDULLAE : AN IMMUNOHISTOCHEMICAL STUDY

BACKGROUND: 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. CONCLUSIONS: 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.