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.