What happens to the wall of the uterus during menstruation ?

Explanation

1) During early stage of menstruation the cells in the wall of uterus increase in number by repeated mitoticd divisions.
2) The inner lining of uterus increase in number by repeated mitotic division.
2) The inner lining of uterus becomes thick and soft with lot of blood cappilliaries in it.
3) These changes in the uterus are necessary because the ovum released by the ovray gets fertilised by the sperm,then the uterus has to keep this fertilised ovum for further development and supply it with food and oxygen, etc.