Follicle Stimulating Hormone antibody (FSH) is a hormone found in humans and other animals. It is synthesized and secreted by gonadotrophs of the anterior pituitary gland. FSH is involved in the maturation of ovarian follicles and estrogen secretion in females. In males, FSH stimulates the secretion of testosterone. Studies have shown that FSH may be a useful marker in the study of pituitary disease, classification of pituitary tumors and in the differential diagnosis of primary and metastatic tumors of the pituitary.