Yolk Sac Formation In Early Embryo: Simplified For Students

Yolk Sac Formation In Early Embryo: Simplified For Students

Question 1. Yolk sac
Answer:

• As the fluid from the uterine cavity enters morula, it gets converted to blastocyst The outer layer of it is formed by trophoblast and inner layer by inner cell mass
• Some of the inner cell mass layer cells become flattened – these are called hypoblast
• Remaining cells become columnar to form epiblast
• The space between epiblast and hypoblast is called amniotic cavity
• Flattened cells from hypoblast spread and line blastocytic cavity and form primary yolk sac
• After formation of extra-embryonic coelom, the yolk sac becomes smaller and lined by cubical cells and form secondary yolk sac

Question 2. Effects of fertilization:
Answer:

Effects of fertilization Fertilization:

• It is the process by which male and female gametes fuse is known as fertilization.
• Site: In the ampullary region of the uterine tube.
• Effects:
  • Binding of sperm to zona pellucid of the ovum.
  • Penetration of the sperm through the zona pellucida
  • Fusion of the cell membranes of the sperm and the ovum.
  • Release of acrosomal enzymes.
  • Prevention of entry of other spermatozoon into the oocyte.
  • Metabolic changes within the ovum.
  • The diploid chromosome number is restored.
  • Sex determination takes place.