Here we see the 3 layers of the adrenal cortex, followed by the medulla of the adrenal gland. The zone glomerulosa is the most superficial layer and is the main source of mineralocorticoids. Next is the zona fasciculata, which is the thick middle layer. It consists of parallel fascicles, blood capillaries, spongiocytes, and secretes glucocorticoids and androgens. The 3rd layer is the zone reticularis which forms a branching network and also secretes glucocorticoids and androgens.