While approximately 200-300 million sperm are produced per day in men who can have children, only half or 100 million of them turn into live sperm. Sperm reaches the epididymis 72 days after it begins to be produced in the testes, the male ovaries. The epididymis is an appendage organ consisting of thin microscopic tubes that are densely wrapped behind the testicles and extends along the testicle, just behind the testicle. As the sperm moves through the epididymis, it matures and gains the ability to fertilize and move on its own. Semen analysis reflects the event weeks ago.
After ejaculation, the semen first coagulates and then liquefies with prostate enzymes within 20-30 minutes. The alkaline pH of the semen temporarily protects the sperm from vaginal acidity, and any sperm remaining in the vagina die within two hours. 35% of sperm are lost by reflux. 90 seconds after ejaculation, sperm reaches the uterus through the cervix. Only 1% of the sperm reaches the woman's tubes, which is the area where fertilization with the egg will occur.
Under the influence of estrogen, the female hormone, the cervix secretes a high amount of watery mucus (>96%). The water ratio of mucus is directly related to sperm passage. The pregnancy rate is higher in sexual intercourse on the day when the highest amount of watery mucus is produced. The mucus of the cervix prevents the passage of sperm with poor motility and morphology. Mucosal folds form channels extending towards the inner cavity of the uterus.
Sperm Cells Reaching the Tubes
Sperm passes from the mucus in the cervix to the fallopian tubes within 5 minutes. Sperms live for 1-3 days in the cervical canals during the ovulation period, when the mucus is most optimal, and the cervix serves as a storage for sperms for up to 72 hours. After ejaculating into the vagina, the sperm advances towards the cervix, uterus and tubes with its own movements at a rate of 2.7 mm per minute. It reaches the tubes in 65-70 minutes. Sperm transport is greater in the tube on the side where the egg is located.
After ejaculation, only a few hundred (<1000) of the 200-300 million sperm in the semen can reach the vicinity of the egg. Sperm is not stored in the tubes. The inner surface cells of the tubes are the most suitable environment to maintain the fertilization ability and mobility of the sperm. However, normal movement and morphology of sperms do not guarantee passage through the tubes.
Tupl. Mucosal folds and mucus on the inner surface of the penis slow down the passage of sperm in the tube, thus prolonging the presence of sperm in the fallopian tube and preventing more than one sperm from fertilizing the egg. The sperm's fertilization of the egg takes place in the ampulla region of the tube.
Sperms must first go through some stages in order to gain the ability to fertilize. Only sperm that have completed the capacitation process can move towards the ampulla region of the tube. Capacitation is the process in which sperms fully acquire the ability to fertilize within the reproductive ducts and become suitable for fertilization.
At the end of capacitation, the sperm acquires the features of the Acrosome reaction, binding to the zona pellucida, the outer membrane of the egg, and hyperactive movement. Capacitation ensures hypermotile sperm, and the increased speed is a critical factor in passing the zona, the outer membrane of the egg. The capacitation process takes an average of 7 hours.
When the sperm reaches the place where the egg is or comes into contact with the liquid containing the egg, called follicular fluid, it undergoes further and more serious changes. Some of the capacitation occurs in the epididymis, which are the male ducts, and some of it occurs when it passes through the mucus in the woman's cervix.
Although capacitation is defined as the changes that the sperm will undergo in the female genital tract, when the sperm is kept in special liquid environments in the laboratory for a short time, it does not occur in the female reproductive tract. It can also gain fertilization ability. The time required for capacitation in the laboratory environment is 2 hours.
When the sperm approaches the egg, an ACROSOMAL REACTION occurs, which is necessary for the sperm to cross the egg membrane. It passes through the egg membrane by releasing ACROSIN, an enzyme that dissolves the sperm membrane.
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