Question

Explain the term
a) Implantation
b) Placenta

Answer 1

Hint: There is a series of events that take place before and after pregnancy. After ovulation, if the egg is not fertilized, then the menstrual cycle goes on smoothly. But if fertilization takes place, the zygote formed after fertilization moves down the fallopian tube and comes to the uterus. Then a series of events take place.

Complete answer:
Both the processes are related to the gestation period in humans.
a) Implantation- It is defined as the stage of human pregnancy where the attachment of the fertilized egg takes place to the lining of the uterus wall. It is at this stage when a woman is said to be pregnant. It occurs after \[8 - 9\] days after fertilization and as late as $12$ days after ovulation. There are some symptoms of implantation including, bleeding or spotting, nausea, mood swings, mild cramps, bloating, and headache.
b) Placenta- It is a complex double-layered spongy vascular tissue in human females formed by the joint activity of the maternal part (endometrium) and fatal tissue (chorionic sac) in the wall of the uterus. It is meant for the attachment, nourishment, respiration, and waste disposal of the fetus. It stays till the entire gestation period is over and the baby is delivered.

Note:
Some of the complicated cases of pregnancy are due to improper implantation of the embryo. The implantation can take place anywhere in the uterus, whether on the left or right endometrium. But sometimes it takes place in the fallopian tubes itself, known as Ectopic pregnancy/tubal pregnancy which might be life-threatening.