What Are Sperm Cells?

Marlene de Wilde

Sperm cells are the male gametes, or cells that function in sexual reproduction, before fertilization. Gametes merge with another gamete, in this case the female egg cell, to form a zygote. A zygote is the ovum, or egg, after fertilization. Sperm is short for spermatozoon, and spermatozoa in the plural form.

Sperm is the reproductive cell in males that fertilizes an egg cell.
Sperm is the reproductive cell in males that fertilizes an egg cell.

In mammals, sperm cells are produced in the male testes. The testes, or testicles, produce over 4 million new sperm every hour. Sperm cells are produced by a cell division called meiosis, which results in each cell having 23 chromosomes, which is half of the chromosomes found in every other cell in the human body except for the female egg, which also contains only 23. When joined, however, they make up the requisite 46 chromosomes, a pair made up of one chromosome from the male and one from the female, necessary for healthy development.

Hot tubs and baths lessen the life of sperm.
Hot tubs and baths lessen the life of sperm.

There are three parts to a healthy sperm cell. There is a head capsule which contains a nucleus, the middle part is called the mitochondria and the long tail is called the flagellum. The nucleus contains the genetic material from the 23 chromosomes. Mitochondria in the body of the cell provides the energy for the swimming activity necessary for the sperm to reach the egg. The side to side movement of the flagellum is made possible by the alternate contraction of the protein fibers that make up the tail, providing the impetus to reach the female egg once the sperm have entered the vagina. There are between 200-500 million sperm cells in a single ejaculation.

Not all of the cells released into the vagina will survive the journey up the cervix to the fallopian tubes. Only the living sperm that are healthy and straight will have any chance of reaching the egg, a feat which requires the microscopic sperm to swim for up to an hour. If there is no egg to be fertilized, the cells can stay alive for up to five days or more in the female reproductive tract.

Male fertility depends on how healthy the sperm cells are and the health of the cells depend to a large extent on lifestyle. Men who are overweight, do not get enough exercise or follow diets lacking in fruit and vegetables may find that their sperm is not as fertile as normal. Stress and pollution also play a major role in decreasing sperm health.

A zygote forms after sperm cells join with an egg.
A zygote forms after sperm cells join with an egg.

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Discussion Comments


The ones who get me are the stupid kids who try to find every way around using birth control! They think that "just once" without protection isn't likely to cause pregnancy. Well, all it takes is one single sperm cell making it to its destination to start a pregnancy.

Or, they'll say they use the "withdrawal" method, or douche with a soda afterward and they won't get pregnant. Good grief. The pathetic ignorance is rampant.

I can't believe how many people are so completely uneducated about sex in a first world country!


I find it amazing how many people know so little about their bodies. I have had women ask me (I'm not a doctor) if, since they've had an ovary removed, if they can only have boys or only girls, since someone told them their "boy ovary" or "girl ovary" was the one removed. How absurd! Do they not know the *male* determines the sex of the child? The woman always produces "X"

chromosomes and the sperm cell carries either an "X" chromosome, in which case the baby will be a girl, or a "Y" chromosome, in which case the baby will be a boy.

In the U.S., anyway, sex education classes are supposed to be taught everywhere, and, I'm assuming, using curriculum printed sometime in the last 20 years.

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