Pituitary gland. Coloured scanning electron micrograph of tissue of the pituitary gland, also known as hypophysis. Pituitary secretory cells are pale red-brown; capillaries (blue), also known as sinusoids, are seen at centre and top; a large, activated macrophage (yellow) is visible in the sinusoid at centre. The hypophysis is an endocrine gland found in the brain which secretes two functional groups of hormones: hormones which act directly on non-endocrine tissues such as the growth hormone and hormones which stimulate the activity of other endocrine glands. Magnification: x2100 at 6x7cm size.