Frequently Asked Questions About Semen, Sperm, and Vaginal Discharge

What is semen?

Semen is a mixture that comes from secretions of the testes, seminal vesicles, prostate, and bulbourethral glands (Cowper’s glands). and is the medium of travel for the sperm.  Seminal plasma is the most prominent ingredient of human semen. Seminal plasma is a fluid that is secreted by the seminal vesicles and prostate gland, which make up the male reproductive organs. The seminal plasma mediates the chemical function of the ejaculate.  Semen’s purpose is to feed and protect the spermatozoa (sperm cell) during their long trip up to the female’s ova via acidic conditions it encounters in the female vagina.  Over 95% of the ejaculate volume originates from the sex accessory tissues and not from the testes, as is often mistakenly believed. A human male’s ejaculate volume is about 3 ml and ranges from 2 to 6 ml. Of the 3 ml of an ejaculate, a very small proportion, 0.2 ml, originates from the Cowper’s gland and 0.5 ml from the prostate gland. The largest portion, approximately 2 ml, is secreted from the seminal vesicles and appears in the latter portion of the ejaculate volume.


What is sperm?

The mature fertilizing gamete of a male organism, usually consisting of a round or cylindrical nucleated cell, a short neck, and a thin motile tail. Also called sperm cell, spermatozoon.


What is vaginal discharge?

This is the discharge of secretions from the cervical glands of the vagina; normally clear or white.  This discharge is normal and varies during menstruation.  Semen can be detected in vaginal discharge up to 10 days after intercourse.  Acid Phosphatase from semen in vaginal discharge can be detected up to 72 hours after ejaculation. Prostate Specific Antigen (PSA) is commonly detected in vaginal discharge up to 7 days and we have several cases specified by customers that the intercourse was at 10 days (DNA matches spouse).  See this link for variations of vaginal discharge.

How do I detect vaginal discharge in my husband’s underwear?

Please select this link for more information.

What if the man cannot produce sperm?

DNA is found in sperm, not semen. If an individual is vasectomized or azoospermic (producing no sperm), DNA will only be available from the epithelia cells shed during ejaculation. The success rate of a DNA extraction from a stain containing semen from a vasectomized or azoospermic individual is greatly reduced but is still possible.