Pituitary gland blood vessels. Coloured scanning electron micrograph (SEM) of a resin cast of blood vessels in the pituitary gland. The smallest blood vessels, capillaries, are coiled around and through the gland, while larger blood vessels, such as the arteries on either side, bring blood to and from the capillaries. The pituitary gland, an endocrine gland, is at the base of the brain. It has two sections, the posterior (ring-shaped) and anterior (ball-shaped) lobes. The pituitary hormones, secreted directly into the bloodstream through the permeable capillary walls, control a wide range of functions, including kidney and thyroid function. The cast was made by injecting resin into the blood vessels. The surrounding tissues were then chemically digested.