Human Reproduction

The human reproduction cycle starts with the penetration of the penis into the vagina resulting in ejaculation of the spermatozoonatozoonatozoa. The spermatozoon then travels up the cervix undefiled the uterus tract and into the ovary ducts with the help of chemotaxis quest a hunt of progesterone secreted by cells surrounding the tributary oocyte, where a secondary oocyte from a graffian follicle is awaiting fertilization. Fertilization begins with the binding of a sperm taste to the glycoprotein coating of the unessential oocyte called the zone pellucida. Exocytosis of the acrosome at the tip of the sperm head releases enzymes that digest a path through the geographical zone and enable the sperm head to bind to the plasma tissue layer of the oocyte, as soon as this happens the secondary oocyte goes into meiosis pin two. When the spermatozoa fuses with the zona pellicuda it disintergrates leaving only the heart and soul to immortalize the secondary oocyte, the secondary oocyte and the spermatozoa have 23 chromosomes each and when the nucleus enters the secondary oocyte it is now a secondary oocyte with 46 chromosomes. short the nucleus of the successful sperm enlarges into the male pronucleus. At the like time, secondary oocyte completes meiosis II forming a second paired physical structure and the distaff pronucleus, it is now known as an egg cell.

The male and female pronuclei move toward each opposite while duplicating their DNA in S phase. Their nuclear envelopes disintegrate. A spindle is formed following replication of the sperms centriole, and a salutary launch of dyads assembles on it. The fertil! ized ovum now known as the fertilized ovum is now go down for its first mitosis. When this is done, 2 cells each with a diploid set of chromosomes are formed. cleavage now happens which is a series of rapid mitotic divisions that subdivides the cytoplasm of the zygote into smaller, essentially equipotential cells called blastomeres contained by the zona pellucida. Cleavage generates a cellular system essential for further...If you want to sign a unspoilt essay, order it on our website: OrderCustomPaper.com

If you want to get a full essay, visit our page: write my paper