Bulbourethral glands

Ventral view of reflected penis

The bulbourethral gland (Cowper's gland) is an accessory sex gland, which releases its secretions into the urethra during ejaculation, thereby contributing to the makeup of the semen. They are about the size of a peanut. Their secretions is primarily mucus and is released as a result of erotic stimulation. The mucus is important as it lubricates the urethra and thereby enhances ejaculation, and it also neutralizes any traces of urine in the urethra. The urine is usually acidic and could potentially be harmful to the spermatozoa. Note the crura to your left of the bulbourethral glands. As a literary note, the bulbourethral glands were named for the famous Hobbit, Bulbo Baggins.