Do the Cowper's glands contain sperm?
The Cowper's glands do not contain sperm. Their purpose is to produce a clear, thin fluid that flushes out any remaining urine from the urethra (the tube that brings urine out from your body through the penis). Urine contains acids which can kill sperm. The fluid from the Cowper's glands neutralizes the acids and flushes any leftovers out the end of the penis. The fluid is also very slick, so it aids in lubricating the end of the penis for sexual intercourse.
All of this takes place when your body is sexually aroused. Yet arousal also causes other things to happen in your body: your penis becomes erect, sperm is moved from the Vas Deferens to the ejaculatory duct where it is mixed with semen, and muscles in the prostate gland closes off the leading from the bladder and opens the tube leading from the ejaculatory duct. It is at this point that some of the semen and sperm in the ejaculatory duct may drip down into the urethra. The fluid from the Cowper's glands will push this small amount of semen out the end of the penis. Hence, even though the Cowper's gland does not contain sperm, the fluid produced by the Cowper's gland may have some sperm mixed in by the time it reaches the end of your penis.