What is the role of zona pellucida in fertilization . Analize the cganges during the ovum during fertilization .

Dear student.

Please find the solution below.

During fertilisation, when a sperm comes in contact with the zona pellucida layer of the ovum a cortical reaction takes place which leads to a modification of the zona pellucida that blocks polyspermy.
 

After copulation, the semen leaves the male body through the penis into the female reproductive system. It passes through the vagina to the female uterus and fertilizes the ovum in the fallopian tube – the oviduct. Oviduct is a muscular tube that carries the fertilized egg to the uterus for the further development.

  • Fertilization occurs in the fallopian tube if copulation takes place during ovulatory period. The ovum released by the ovary is also transported to the ampullary-isthmic junction where fertilisation takes place. Fertilisation can only occur if the ovum and sperms are transported simultaneously to the ampullaryisthmic junction. This is the reason  why not all copulations lead to fertilisation and pregnancy.
  • Embryo’s development starts immediately and menstruation stops.
  • Embryo moves down to the uterus and implantation occurs.
  • The time period of foetus development till birth is called gestation. Foetal development inside the mother’s body takes approximately 9 months.
  • By the end of gestation the act of giving birth is called as parturition

Note: Only one sperm can enter the egg and immediately after that, the egg emits chemicals that prevent more sperm from entering. But by mutation, rarely if two or more sperms enter the egg, it cannot survive. It will create a wrong genetic material and never develop into a fetus. 

Regards.


 

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