Which gland is responsible for producing a fluid that cleanses the urethra before ejaculation?

The correct answer is the structure known as the bulbourethral glands. These glands produce a pre-ejaculatory fluid that helps to cleanse and lubricate the urethra before ejaculation occurs. This fluid is important for providing a more favorable environment for sperm as it passes through the urethra, clearing out any residue or acidity that could harm sperm viability.

In addition to contributing to lubrication, the bulbourethral glands also play a role in neutralizing the acidity of any urine present in the urethra, ensuring that the passage is suitable for sperm. This cleansing action is crucial for reproductive success.

The other glands listed serve different functions. The vesicular glands, also known as seminal vesicles, contribute seminal fluid high in fructose and nutrients for sperm, while the prostate gland adds additional secretions to the semen, including enzymes and buffering agents, but these are not primarily responsible for cleansing the urethra. The corpus luteum is not a gland associated with the male reproductive system; rather, it relates to female reproduction and is involved in hormone production following ovulation.