The monthly cyclical changes which occur in the ovaries and lining of the uterus (endometrium) of females, starting with the preparation of an oocyte for fertilization to the shedding of endometrium is known as menstrual cycle.Complete answer:
Menstrual cycle is approximately a 28-day cycle. The cyclical changes which occur during menstrual cycles are quite dynamic in nature.
1. A secondary oocyte is prepared by oogenesis and the Graafian follicle starts growing larger by action of follicle stimulating hormone (FSH).
2. Simultaneously, the endometrium wall thickens. On day 14 or 15, ovulation occurs, luteinizing hormone level reaches its peak, causing ovulation.
3. Oocyte along with some cells gets released from the ovary and reaches the fallopian tube where fertilization could occur. Meanwhile, the uterus prepares for fertilization; follicle turns into corpus luteum, releasing progesterone.
4. After a period of about 24 hours, if fertilization does not occur, ovum reaches the uterus and signals for endometrial shedding.
5. The shedding marks initiation of a new cycle.So, the correct answer is 1 i.e. true.Note:
The shedding of endometrial lining, blood and mucus is called menstruation. In other Primate females, the cyclical changes that occur are called oestrous cycles.