Summing up: The composition of semen
The semen discharged in an ejaculation (usually somewhat less than a teaspoonful) is composed of sperm cells and secretions from the epididymides, the seminal vesicles, the prostate gland, and the bulbourethral (Cowper's) glands. None of these fluids contains any harmful substances. People who swallow semen, whether by accident or on purpose, have no reason to fear any ill effects (except, of course, if the semen carries bacteria or viruses causing a sexually transmitted disease). Semen is usually thick and greyish white in color. However, at times it may also be thin and rather watery. The exact amount, consistency, and composition of semen depends on the frequency of ejaculations. An ejaculation usually contains between 150 and 500 million sperm cells, with 200 million representing an average amount. The number varies from one person to another and even in the same individual, depending on his age and frequency of ejaculations.