Scrotum
The scrotum is a cutaneous pouch containing the testes and part of the spermatic cord. Immediately beneath the skin is a thin layer of muscular fibers (the cremaster), which is controlled by temperature and contracts or relaxes to lower or raise the testes in relation to the body. This muscular activity of the scrotum is necessary to regulate the temperature of the testes, which is important in the maturation of sperm cells.

Penis
The penis is a cylindrical organ that conveys urine and semen through the urethra to the outside. The penis is composed of three columns of spongy cavernous tissue, bound together by connective tissue and loosely covered by a layer of skin. Two of the columns, the corpora cavernosa, lie superiorly side by side; the third column, the corpus spongiosum, lies below the other two columns. The urethra is located in the corpus spongiosum. The dilated distal end of the corpus spongiosum is known as the glans penis (fig. 1-60). The urethra terminates at the glans penis.

The cavernous tissue becomes greatly distended with blood during sexual excitement, causing an erection of the penis. The loose skin of the penis folds back on itself at the distal end (forming the prepuce, or foreskin) and covers the glans. The prepuce is sometimes removed by a surgical procedure called a circumcision.