Pre-ejaculate

Pre-ejaculate (also known as pre-ejaculatory fluid, pre-seminal fluid, or Cowper's fluid, and colloquially as pre-cum) is the clear, colorless, viscous fluid that is emitted from the urethra of the penis during sexual arousal. It is similar in composition to semen but has some significant chemical differences. The presence of sperm in the fluid is variable. Research has found low levels of or no sperm in pre-ejaculate, though these existing studies examined small samples of men. Two contrary, yet non-generalizable studies that found mixed evidence, including individual cases of a high sperm concentration, were published in 2011 and 2016. Pre-ejaculate is believed to function as a lubricant and an acid neutralizer.

The fluid is discharged during arousal, masturbation, foreplay or at an early stage during sexual intercourse, some time before the man fully reaches orgasm and semen is ejaculated. It is primarily produced by the bulbourethral glands (Cowper's glands), with the glands of Littre (the mucus-secreting urethral glands) also contributing.

The amount of fluid that the human male issues varies widely among individuals. Some men do not produce any pre-ejaculate fluid, while others emit as much as 5 ml.

Pre-ejaculate contains some chemicals associated with semen, such as acid phosphatase. Some semen markers, such as gamma-glutamyltransferase, are completely absent from pre-ejaculate fluid.

Acidic environments are hostile to sperm. Pre-ejaculate neutralizes residual acidity in the urethra caused by urine, creating a more favorable environment for the passage of sperm. The vagina is normally acidic, so the deposit of pre-ejaculate before the emission of semen may change the vaginal environment to promote sperm survival.

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