What is the function of the Cowper's glands?

The Cowper's glands, also known as bulbourethral glands, play an important role in the male reproductive system primarily by secreting a clear, mucus-like fluid that serves to lubricate the urethra. This secretion is released during sexual arousal and helps to neutralize any acidity in the urethra, creating a more hospitable environment for sperm as they travel through the urethra during ejaculation. This lubricating function is essential for the ease of passage of sperm and can contribute to better reproductive health.

In contrast, while the other choices mention functions such as sperm production, regulation of testosterone levels, and filtering toxins from the blood, these are associated with different organs or systems. Sperm production is primarily the function of the testes. The regulation of testosterone levels primarily occurs through the hypothalamus and pituitary gland interactions, and the liver and kidneys are responsible for filtering toxins from the blood, not the Cowper's glands. Thus, the primary function of the Cowper's glands is accurately described by their role in lubricating the urethra.