Define (i) menarche, and (ii) menopause.
Menstruation: -The cycle of events taking place in female reproductive organs under control of sex hormone, in every 28 days and marked by bleeding or menstrual flow is called menstruation.
It is the stage of initiation of menstruation in the life of a female girl. it generally occurs at an age of 11-13 years. It refers to the beginning of the reproductive phase in girls.
It is the stage at which menstruation stops In the life of women . it occurs in women at the age between 45-50 years. It refers to the end of the reproductive phase in the women.