The term sperm is derived from the Greek word ”sperma” (meaning “seed”) and refers to the male reproductive cells. The human sperm cell is the reproductive cell in males and will only survive in warm environments, once leaving the body the sperm’s survival is reduced and may cause the cell to die. Sperm cells come in two types; “male” and “female”. Sperm cells that give rise to female (XX) offspring after fertilization differ in that they carry an X chromosome, while sperm cells that give rise to male (XY) offspring carry a Y chromosome.
On a dry surface, such as clothing or bedding, sperm are dead by the time the semen has dried. In water, such as a warm bath or hot tub, sperm will likely live longer because they thrive in warm, wet environments. Inside a woman’s body, sperm can live for up to five days depending on the conditions. If you have unprotected sex even a few days before your partner ovulates, there is a chance of achieving a pregnancy. It takes just one sperm to fertilize an egg and achieve a pregnancy, but for each sperm that reaches and fertilizes an egg, there are millions that don’t. The average ejaculation contains close to 100 million sperm.
The semen must travel from the vagina to the fallopian tubes, an arduous journey that few sperm survive. For those that complete the trip, penetration of the egg is far from a sure thing. The egg is covered by a thick layer that makes fertilization difficult. Experts believe this process may be nature’s way of allowing only the healthiest sperm to fertilize the egg, thereby providing the best chances to produce a healthy baby.
Sperm concentration. Also called sperm density, this is the number of sperm in millions per milliliter (mL) of semen. Twenty million or more sperm per mL is considered normal. Sperm motility. This is the percentage of sperm in a sample that are moving as well as an assessment of their movement. One hour after ejaculation, at least 50% of sperm should be moving forward in a straight line. Unlike women, whose fertility ends at menopause, men can continue to be fertile throughout life. Although sperm production decreases with age, men continue to produce sperm, and even elderly men have fathered children.