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Question
What are the phases of the menstrual cycle? Indicate the changes in the ovary and uterus.
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Solution
The four phases of the menstrual cycle are:
- Menstrual or Destructive phase
- Follicular or Proliferative phase
- Ovulatory phase
- Luteal or secretory phase.
Events of the menstrual cycle and changes in the ovary and changes in the uterus.
| Phase | Days | Changes in Ovary | Changes in Uterus | Hormonal changes |
| Menstrual phase | 4 – 5 days | Development of primary follicles. | Breakdown of uterine endometrial lining leads to bleeding. | The decrease in progesterone and estrogen. |
| Follicular phase | 6th – 13th day |
Primary follicles grow to become fully mature Graafian follicles. | Endometrium regenerates through proliferation. | FSH and Oestrogen increase. |
| Ovulatory phase | 14th day | The Graafian follicle ruptures, and releases the ovum (egg). | Increase in endometrial thickness. | LH peak. |
| Luteal phase | 15th – 28th day | Emptied Graafian follicle develops into corpus luteum. | The endometrium is prepared for implantation if fertilization of the egg takes place if fertilization does not occur corpus luteum degenerates, uterine wall ruptures, bleeding starts, an unfertilized egg is expelled. | LH and FSH decrease, Corpus luteum produces progesterone, and its level increases followed by a decline if menstrual bleeding occurs. |
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