Adrenal Medulla

In the adult adrenal, medulla is present in the body and head of the gland. The image shows zona reticularis at the top and adrenal medulla in the lower two-third. Medulla is composed of chromaffin cells arranged in anastomosing cords surrounded by a prominent network of fenestrated capillaries. Epinephrine is the main hormonal product. Small amounts of norepinephrine are also produced here. Ultrastructurally, the chromaffin cells of the adrenal medulla contain numerous membrane-bound, electron-dense secretory vesicles containing catecholamines.