In Depth: Sagittal Cross-section
The corpus spongiosum is yet another part of the male anatomy that facilitates sexual reproduction. It is a soft, spongy tissue that surrounds the urethra.
While the corpus cavernosum’s physiologic role is to become engorged with blood to make the penis erect, the corpus spongiosum itself remains spongy and limber to protect the urethra from closing during an erection. Because of the corpus spongiosum, semen can travel down the urethra and out of the penis during ejaculation.
A typical sexual episode for the average man works like this:
- Whether physical or mental, a man’s sexual stimulation begins in the brain. From there, the body sends signals to nerves within the penis, particularly the dorsal nerve of the penis.
- This signals the corpora cavernosa, which is comprised of two cylinder-like columns of tissue, to begin to fill with blood. This process causes the penis to become erect.
- With further stimulation, a man becomes increasingly aroused. During this time, the penis expands more.
- Stimulation of the nerves in the exterior of the penis sends signals back and forth to the brain. This signals the appropriate vessels, organs, and glands to be at the ready.
- As the man comes close to orgasm, the Cowper’s gland releases a clear liquid that prepares the urethral tract for the semen. This liquid, known as pre-ejaculate, kills any harmful elements that may have been left by urine.
- As the man is about to ejaculate, the testes release sperm through the epididymides, two long, twisted tubes connected to the testes that connect to the vas deferens, other tubes that transport sperm before ejaculation.
- From there, the sperm travel to the seminal vesicle, which, along with the prostate, secretes fluids that mix with the sperm and comprise the majority of semen.
- When the man climaxes, the semen travels down the urethra, through the glans penis, and out the tip of the penis. The urethra remains open despite the engorged muscle tissue around it thanks to the corpus spongiosum.
- After ejaculation, the blood drains out of the corpora cavernosa and returns to other parts of the body.
Cells within the ejaculate typically live for only a few hours.