The Menstrual Cycle

1 The menstrual cycle marks the sexual maturity of a girl.

2 A girl is born with all the eggs that she will release throughout her life.

3 For fertilisation to take places a mature ovum must be released from one of the female's ovaries.
4 About once every 28 days, a mature ovum is released into the Fallopian tube during a process called ovulation.

5 (a) If the ovum is not fertilised, menstruation takes place.
(b) Menstruation is the breakdown of the uterus lining and its gradual discharge through the vagina.
(c) Menstruation lasts from four to five days.
(d) The length of a menstrual cycle is the number of days from the first day of one menstruation to the first day of the next menstruation.

6 (a) The menstrual cycle is the monthly cycle of changes that occur in the walls of the uterus, the ovary and the vagina,
(b) The walls of the uterus undergo changes that are closely related to the development and release of the ovum.



7 A complete menstrual cycle involves
(a)Menstruation
(b) changes in the thickness of the walls of the uterus
(c) the development of the ovum in the ovary
(d) ovulation (the release of the ovum)

8 Figure shows the thickening of the uterine lining and the changes that occur in the ovary throughout the menstrual cycle.

Menstruation
•24 hours after ovulation, the unfertilised ovum dies.
•The thick lining of the uterus is not needed and starts to break down.
•The unfertilised ovum together with the uterine lining and blood are shed and menstrual flow begins.
•Menstruation stops after about three to five days.