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Pre-ejaculate (also known as pre-ejaculatory fluid, preseminal 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 no or low levels of sperm in pre-ejaculate, though these existing studies are non-generalizable due to examining small numbers of men.〔〔〔 A contrary, yet non-generalizable study that found mixed evidence, including individual cases of a high sperm concentration, was published in March 2011. Pre-ejaculate is believed to function as a lubricant and an acid neutralizer. The amount of pre-ejaculate emitted varies widely between individuals, and may depend on circumcision status; some men emit none. ==Origin and composition== 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.〔, which cites: 〕 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pre-ejaculate」の詳細全文を読む スポンサード リンク
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