question_answer 67)

  What changes are observed in the uterus if fertilization does not occur?

Answer:

                  If the egg is not fertilized, it lives for about one day. Since, the ovary releases one egg every month, the uterus also prepares itself every month to receive a fertilized egg. Its lining becomes thick and spongy. This would be required for nourishing the embryo if fertilization had taken place. Now, however, this lining is not needed any longer. So, the lining slowly breaks and comes out through the vagina as blood and mucous. This cycle takes place roughly every month and is known as menstruation. It usually lasts for about two to eight days.