Question

What are the changes that occur in the uterus if:-
(i) Fertilization occurs
(ii) When fertilization does not occur

Answer 1

Answer:

When the ovum remains unfertilized, the corpus luteum starts to degenerate and the level of progesterone in the blood decreases.

∙ This causes the failure of maintaining the endometrium lining and hence it ruptures.

∙ The unfertilized ovum, ruptured endometrium, about 50 ml of blood and mucus are discharged from the vaginal opening.

∙ This is called menstrual flow or menstruation.

∙ The decreased level of progesterone and estrogen stimulates the hypothalamus to release FSH-RH which further stimulates pituitary glands to release FSH leading to the follicular phase.

Answer 2

The changes that occur in the uterus are:-

√ if fertilization occurs:- The inner lining of the uterus will become *thick*

√if fertilization doesn't occur:- Breakdown of the inner lining of uterus i.e *menstruation*

• Every month uterus prepares itself to receive the fertilized egg.

• If the egg is fertilized by sperm then it travels down the fallopian tube.

•Now this fertilized egg will get attached to the lining of the uterus.

• The lining of the uterus becomes thick to support the developing embryo.

• Now, the *placenta* develops (The placenta is a large organ that develops during pregnancy)

• Placenta transfers oxygen and important nutrition from the mother to the foetus.

•In case, the egg is not fertilized then, the inner lining of the uterus *breaks down.*

• The breakdown of the inner lining of the uterus is called *MENSTRUATION*.