Erectile tissue is any tissue in the body that is capable of achieving stiffness. This state is usually achieved when it is filled with blood. Although erectile tissue is most commonly associated with sexual anatomy, it can also be found in other parts of the human body, such as the ears and nose.

The penis is the best known location for erectile tissue. This organ actually contains three tissue sections. Two of them form a pair called the corpus cavernosa, while the third is named the corpus spongiosum. Known as corpus cavernosum in singular form, the corpus cavernosa are named for their cave-like structure. They line the penis shaft, with both sections joining together at its head.

The smaller tissue, the corpus spongiosum, is named for its sponge-like sections. In earlier times, it was referred to as the corpus cavernosum urethrae because it surrounds the urethra of the penis. This structure transports the organ's urine and semen.

The erectile tissues of the penis work together to make sure that the penis is rigid enough to indicate sexual arousal and possible sexual intercourse. The corpora cavernosa's chambers receive a certain amount of blood to harden the organ, a state known as tumescence. Meanwhile, the corpus spongiosum retains an elastic state to allow ejaculation, which is the ability to eject semen. The inability to achieve penile erection translates into erectile dysfunction (ED).

The corpus cavernosum clitoridis is the erectile tissue that serves as the female equivalent of the corpus cavernosum penis. Like the male reproductive organ, the clitoris has a pair of this type of erectile tissue. The vestibular bulbs, also known as the clitoral bulbs, are also included. They flank the female urethra, the sponge that surrounds it, and the vagina.

The two different types of erectile tissue in the clitoris have virtually the same functions as the corpora cavernosa and corpus spongiosum. The corpus cavernosum clitoridis and the vestibular bulbs fill with blood to cause clitoral erection. The latter, however, has the additional capability of shackling the vagina's opening. This causes the external borders of the vagina, known as the vulva, to swell in an outward motion.

Erectile tissue in the penis and clitoris are lined by endothelium. This is a thin layer of cells responsible for reducing the instability of the flow of blood, thereby permitting it to travel farther. Also, they have connective tissue known as septa, which enclose and separate them into smaller units. This results in the different types of erectile tissue in the male and female genitalia.