The penis is the male sex organ, reaching its full size during puberty. In addition to its sexual function, the penis acts as a conduit for urine to leave the body.
The penis is made of several parts:
- Glans (head) of the penis: In uncircumcised men, the glans is covered with pink, moist tissue called mucosa.
- Covering the glans is the foreskin (prepuce). In circumcised men, the foreskin is surgically removed and the mucosa on the glans transforms into dry skin.
- Corpus cavernosum: Two columns of tissue running along the sides of the penis. Blood fills this tissue to cause an erection.
- Corpus spongiosum: A column of sponge-like tissue running along the front of the penis and ending at the glans penis; it fills with blood during an erection, keeping the urethra — which runs through it — open.
- The urethra runs through the corpus spongiosum, conducting urine out of the body.