The scrotum is an anatomical male reproductive structure that consists of a suspended sack of skin and smooth muscle that is dual-chambered, present in most terrestrial male mammals and located under the penis.One testis is typically lower than the other, which functions to avoid compression in the event of impact.tream-lined, aquatic mammals such as whales and seals typically lack an external scrotum. It is a distention of the perineum and carries some abdominal tissues into its cavity including the testicular artery, testicular vein and pampinform plexus.