Explain the terms
(I) implantation of embryo
(ii) placenta
Answers
1 Under normal circumstances, fertilization occurs in one of the Fallopian tubes, then the fertilized egg begins to make its way to the uterus. By about the fifth day after conception, the embryo finally reaches the uterus, where it implants itself in the endometrium, or uterine lining.
2 The placenta is an organ that develops in your uterus during pregnancy. This structure provides oxygen and nutrients to your growing baby and removes waste products from your baby's blood. The placenta attaches to the wall of your uterus, and your baby's umbilical cord arises from it.
Answer:
(i) Implantation: The embedding
of a fertilised mammalian egg (embryo) into the inner thick wall of the uterus (womb) where it will continue its development is called implantation.
(ii) Placenta: It is a complex double-layered spongy vascular tissue in human female formed by the joint activity of maternal and foetal tissues in the wall of uterus that is meant for attachment, nourishment and waste disposal for the foetus.
(b) The average duration of human pregnancy is 40 weeks or 280 days.
Explanation: