The prostate (from Greek προστάτης, prostates, literally one who stands before, protector, guardian) is a compound tubuloalveolar exocrine gland of the male reproductive system in most mammals. It differs considerably among species anatomically, chemically, and physiologically.he prostate (from Greek προστάτης, prostates, literally one who stands before, protector, guardian) is a compound tubuloalveolar exocrine gland of the male reproductive system in most mammals. It differs considerably among species anatomically, chemically, and physiologically.