How sperm enters the vagina

After the semen is ejaculated into the vagina during sexual intercourse, most of it accumulates in the posterior vaginal fornix, and the cervix is ??soaked in this semen pool. Under normal circumstances, sperm can enter the cervical canal after a few minutes. The normal vaginal environment is acidic. This environment has important physiological significance for the self-cleaning effect of the vagina, but is not conducive to the activity and survival of sperm.

How do sperm pass through the cervix?

Whether sperm can pass through the cervix is ??closely related to the biochemical properties of cervical mucus. The secretion of cervical mucus is directly affected by the levels of estrogen and progesterone secreted by the ovary. During the pre-ovulatory period, mature follicles secrete a large amount of estrogen, which makes the cervical mucus thinner, as clear and transparent as egg white, and the amount increases. It contains nutrients such as sugar, antibiotics and salts, which provide energy for sperm activity. The cervix plays a screening role for sperm. Only sperm with normal morphology and high motility can pass through the cervix smoothly. Furthermore, there is a substance in the seminal plasma that inhibits sperm activation and is attached to the sperm head. When the sperm passes through the cervical mucus, it can remove these substances and gain the ability to fertilize. This process is called capacitation.

How does sperm move in the uterine cavity?

After the sperm enters the uterine cavity through the cervix, it continues to swim upward with the help of the uterine cavity fluid, and generally does not stay in the uterus. Sperm passes through the uterine horns and reaches the isthmus of the fallopian tube. Of course, sperm will pass through both fallopian tubes, unless there is obstruction in the fallopian tubes.

How sperm passes through the fallopian tube

Sperm travels in the fallopian tube mainly through the short-term segmental contraction of the fallopian tube muscle wall, allowing the sperm and tube fluid to flow to the ampulla of the fallopian tube. The fallopian tube epithelial cells have numerous cilia, and the cilia swing in the direction from the fimbriae to the uterine cavity. After the egg escapes from the ruptured mature follicle, it is captured by the fimbriae of the fallopian tube. The egg itself has no ability to move. Its movement depends on the contraction of the fallopian tube smooth muscle and the swing of the epithelial cilia. It passively moves toward the uterine cavity, where it combines with the sperm flowing upstream and is fertilized. The fertilized egg passively moves into the uterine cavity. Implantation occurs in the endometrium, and a new life begins.