ABSTRACT
Adrenal glands of nonmammals fail to exhibit the anatomical medullary-to-cortical relationships characteristic of mammals. Avian adrenal glands, for example, consist of a mixture of cortical and chromaffin cells with no distinct cortex and medulla found, and cardiac chromaffin cells have been claimed to represent the homologue of the adrenal medulla in lungfishes. Nonetheless, both NE and Epi are produced by pheochromocyters of nonmammals, and their physiologic actions are thought to be similar to those described for mammals (Ch. 72).
