Kidneys of frog are mesonephric. They are elongated, flat and reddish-brown structures with outer edges smooth and convex but inner edges notched and straight. The ventral surface of each kidney has an elongated, narrow, yellow adrenal or suprarenal gland which is an important endocrine gland. To the anterior end of each kidney are attached several small finger like fat bodies and a testis (in male) or ovary (in female)..