Semen is a biological fluid involved in reproduction and secreted by the male reproductive organ. Semen is composed of seminal fluid, sperm, growth hormones, stem cells, nutrients, trace elements and epithelial cells.  Spermatozoa are intended to fertilise an egg. In the vagina, sperm cells have a life span of 2-5 days. If they are frozen, they can be stored for up to 10 years. However, many things can render them ineffective, such as heat, ultrasound, etc.

In men, the ejaculate is made up of the successive or almost simultaneous emission of the following, forming the sperm fluid secreted by Cowper's glands (< 1% of the volume of the ejaculate); prostatic secretions (about 20% of the volume of the ejaculate); secretions from the epididymides containing spermatozoa, then from the vas deferens (about 20% of the volume of the ejaculate); the product of the seminal vesicles (remaining 60% of the volume of the ejaculate).