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- The penis is the male reproductive organ
- containing the urethra, the channel through
- which urine and semen are voided. It
- transfers sperm to the female reproductive
- tract to fertilize the ovum. In mammals, the
- penis is made erect by vessels that fill with
- blood, and in most mammals (but not humans)
- is stiffened by a bone. Snakes and lizards
- have a paired structure that serves as a
- penis, whilst other reptiles have a single
- organ. A few birds, mainly ducks and geese,
- also have a type of penis, as do snails,
- barnacles, and some other invertebrates.
- Many insects have a rigid, nonerectile male
- organ, usually referred to as an
- intromittent organ.
-
- Subject by: Vince Pike
-