The zona fasciculata constitutes the middle and also the widest zone of the adrenal cortex, sitting directly beneath the zona glomerulosa. Constituent cells are organized into bundles or fascicles. Situated along the perimeter of the adrenal gland, the adrenal cortex mediates the stress response through the production of mineralocorticoids and glucocorticoids, such as aldosterone and cortisol, respectively. It is also a secondary site of androgen synthesis. Light micrograph.