Light micrograph of a section through the pituitary gland, a hormone-secreting gland at the base of the brain. It is composed of two lobes, the anterior pituitary (left) and the posterior pituitary (right). Between the two is the pars intermedia (blue). The anterior pituitary, under the influence of the hypothalamus, secretes hormones that regulate physiological processes including growth, reproduction and stress. The majority of the posterior pituitary consists of the pars nervosa, which contains nerve fibres that secrete hormones synthesised by the hypothalamus into the blood stream. Magnification: x13 when printed at 15cm wide.