Fertilization: Process ||Class 12 Biology

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  Fertilization is the fusion of haploid gametes i.e. ova(egg) and sperm, to form the diploid zygote.
  The process of fertilization explained below-
  During copulation, semen is released by the penis into the females vagina close to the cervix and is called insemination. The motile sperms move through the cervix enter the uterus and finally reach the junction of the isthmus and ampulla (ampullary-isthmic junction) of the fallopian tube.
  The ovum released from ovary is also reach the ampullary-isthmic junction of fallopian tube where fertilization takes place. Fertilization can only occur if the ovum and the sperms are reached simultaneously to the ampullary-isthmic junction of the fallopian tube. When a sperm comes in contact with the zona pellucida (the thick transparent membrane surrounding a mammalian ovum before implantation) of the ovum and induces changes in the membrane which blocks the entry of the other Sperms. Thus, it ensures that only one sperm can enter to fertilized an ovum, i.e. secondary oocyte.
  The secretions of the acrosome help the sperm enter into the cytoplasm of the ovum through the zona pellucida and the plasma membrane. This induces the completion of meiotic division of the secondary oocyte. The secondary meiotic division results in the formation of the secondary polar body and a haploid ovum (ootid).
  The haploid nucleus of the sperm and that of ovum fuse together to form a diploid.

Fertilization



Location: India

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