Así es el proceso de fecundación

Fertilization is the incredible story of a sperm overcoming amazing challenges to unite with an egg and create a new life. This is the story of us all… Fertilization… During sexual intercourse, approximately 300 million sperm enter the vagina. Shortly after, millions of them must either flow out or die in the acidic environment. However, many survive thanks to the protective elements of the surrounding fluid. Next, the sperm must pass through the cervix, the lower part of the uterus that opens into the vagina. It usually remains closed, but it stays open for a few days while a woman ovulates. The sperm have the difficult task of swimming through the cervical mucus, which has a very watery consistency designed to help the sperm reach the uterus quickly. Once inside the cervix, the sperm continue swimming toward the uterus, but millions of them will die trying to penetrate the mucus. Some sperm become trapped in the cervix, but they can continue their journey later. Once inside the uterus, muscular contractions help the sperm on their way to the egg. However, the woman's immune system cells, mistaking the sperm for invaders, destroy thousands. Subsequently, half of the sperm enter the empty fallopian tube, while the other half swim to the fallopian tube containing the unfertilized egg. Now, only a few thousand remain inside the fallopian tube. Meanwhile, tiny cilia propel the egg toward the uterus, so the sperm must follow this movement to reach the egg. However, it's important to note that some sperm become trapped in the cilia and die during this part of the journey. On the other hand, certain chemicals in the reproductive tract cause the membranes on the sperm heads to change. As a result, the sperm become hyperactive, making them swim stronger and faster toward their destination. Finally, the sperm reach the egg. At this point, only a few dozen of the 300 million sperm remain on the journey. The sperm must be pushed through this layer to reach the egg's outer layer, the zona pellucida, which prevents more than one sperm from entering, thus ensuring normal fertilization. Within the zona pellucida, there is a small fluid-filled space just outside the ovum membrane, and the first sperm to make contact will fertilize the egg. That's right, after a perilous journey and against all odds, a single sperm adheres to the ovum membrane. In a few minutes, their outer membranes fuse, and the ovum draws the sperm inside. This event causes changes in the membrane that prevent other sperm from adhering to it, and then it releases chemicals that repel other sperm from the egg, making it impenetrable. Meanwhile, inside the ovum, the male genetic material spreads and a new membrane forms around it, creating a male pronucleus. Inside, the genetic material reassembles into 23 chromosomes. Meanwhile, the female genetic material awakens and finishes dividing through the fusion of the sperm and the ovum, resulting in the female pronucleus, which also has 23 chromosomes. Once the male and female pronuclei have formed, tissues called microtubules pull them together, thus uniting the two sets of chromosomes and completing the fertilization process. At this moment, a unique genetic code is created, determining its sex, hair color, eye color, and hundreds of other characteristics. The new single-celled zygote is the beginning of a new human being, and now the fallopian tubes and cilia gently sweep the zygote toward the uterus, where it will implant in the rich uterine walls, growing and maturing for the next nine months until the birth of a new life. If you liked this video, give it a like, share it with all your friends and loved ones so they can learn this valuable information, and leave your opinion in the comments. #Education #Fertilization #Pregnancy