Female Reproductive Tract Influence On Sperm Survival And Selection
Fertilization is the process by which male gamete, also known as spermatozoon, meets up with female gamete to form an embryo that eventually develops into a baby. This meeting requires fertilization to occur at a specific location, which is the site where sperms reside and swim before they meet eggs, and it's called the female reproductive tract. The female reproductive tract consists of various parts such as vagina, uterus, ovaries, fallopian tubes, cervix, and others. These organs work together to facilitate mating and conception. Each part plays a significant role in ensuring survival and selection of sperms during their journey towards egg.
The vagina is the entry point for both sperm and urine and has an acidic environment that helps kill harmful bacteria or viruses present in semen. It also secretes fluid that lubricates the penis during intercourse. Sperms pass through the vaginal wall and enter the cervical opening, which contains cells responsible for killing those that are weakened or damaged. From there, they travel through the uterus, where they encounter another barrier made of mucus produced by specialized epithelial cells lining the uterus walls. The mucus kills off any bacteria while allowing healthy sperm to move forward.
Inside the uterus, sperm are subjected to different physical and chemical conditions to weed out unhealthy ones. The fallopian tube connects the uterus to the ovary, where ovulation occurs. Ova (egg) leaves from the ovary every month, and when it's fertilized, it moves into the uterus where it develops into a baby. If not, it passes out through the vagina.
Sperm can stay alive up to five days inside the female reproductive tract, but this depends on various factors such as age, nutrition, and quality of the male's ejaculate. Only about 1% of all sperms reach the oocyte because of natural selection processes like swimming ability, motility, morphology, chemotaxis, etc., making conception difficult. As the sperm progresses towards egg, its membrane hardens, making it more resistant to changes in pH levels and other environmental factors along the way.
When fertilization happens, an enzyme called hyaluronidase is released by the zona pellucida surrounding the oocyte that allows the sperm to penetrate and fuse with it for successful implantation. However, if it fails to do so within twenty-four hours, it dies away from lack of nourishment and energy. This process prevents multiple pregnancies since only one zygote survives while others die off naturally.