Semen , also known as seminal fluid , is a bodily fluid that contains spermatozoa. Spermatozoa are secreted by the male gonads sexual glands and other sexual organs of male or hermaphroditic animals and can fertilize the female ovum. In humans and placental mammals , seminal fluid is ejaculated through the penis and contains several components besides spermatozoa: proteolytic and other enzymes as well as fructose are elements of seminal fluid which promote the survival of spermatozoa and provide a medium through which they can move or "swim".
The fluid is adapted to be discharged deep into the vagina , so the spermatozoa can pass into the uterus and form a zygote with an egg. Semen is collected from animals for artificial insemination or cryoconservation of genetic material.
Cryoconservation of animal genetic resources is a practice that calls for the collection of semen in efforts for conservation of a particular breed. Depending on the species , spermatozoa can fertilize ova externally or internally. In external fertilization , the spermatozoa fertilize the ova directly, outside of the female's sexual organs.
Female fish , for example, spawn ova into their aquatic environment, where they are fertilized by the semen of the male fish.
Internal fertilization occurs inside the female's sexual organs after a male inseminates a female through copulation. In most vertebrates , including amphibians , reptiles , birds and monotreme mammals, copulation is achieved through the physical mating of the cloaca of the male and female. During the process of ejaculation , sperm passes through the ejaculatory ducts and mixes with fluids from the seminal vesicles , the prostate , and the bulbourethral glands to form the semen.
