Intercellular junctions in the adrenal medulla: a comparative freeze-fracture study.

Observations of freeze-fractured specimens revealed that intercellular junctions in adrenal medulla are different in nature and number according to species. Only gap junctions of diverse size exhibiting characteristic loop-like configurations were found in hamster chromaffin cells. In addition to such gap junctions, polymorphic focal tight junctions occasionally combined with particle clusters or small gap junctions were found in guinea-pig. So far, no intercellular junctions were found in rat. Discussion is focused on the possible function of these junctions, in keeping with their presumably high lability.