During the ovulation phase of the menstrual cycle, ovulation is caused by secretion of:
A. Estrogen
B. Progesterone
C. Luteinizing hormone
D. Follicle- stimulating hormone
Explanation: During the ovulation phase of the menstrual cycle, ovulation is caused by the secretion of Luteinizing Hormone (LH) from the anterior pituitary gland.
Correct Answer:
Luteinizing Hormone (LH)
Explanation
Ovulation is the process in which a mature Graafian follicle ruptures and releases an ovum (egg) into the fallopian tube. This occurs approximately on day 14 of a typical 28-day cycle.
The trigger for this event is a sudden surge of LH (Luteinizing Hormone). This LH surge is stimulated by a high level of estrogen produced by the maturing follicle.
Sequence of events leading to ovulation:
1. Follicle in ovary matures due to FSH (Follicle Stimulating Hormone)
2. Maturing follicle secretes high estrogen
3. High estrogen causes positive feedback to pituitary
4. LH surge occurs
5. Ovulation occurs within 24–36 hours after LH surge
Role of Other Hormones
Hormone Role
FSH Helps growth and maturation of ovarian follicles
Estrogen Thickens endometrium; high level triggers LH surge
Progesterone Secreted after ovulation by corpus luteum; maintains endometrium
LH Causes ovulation and formation of corpus luteum
Summary
👉 Ovulation is caused by LH surge
👉 Without adequate LH, ovulation does not occur.
Other Options Deatails
Here is the explanation and description of all the options:
A. Estrogen
- Estrogen is the primary female sex hormone produced mainly by the ovaries (specifically by growing follicles).
- It helps in the development of secondary sexual characteristics such as breast development and widening of hips.
- It is responsible for the thickening of the endometrium (lining of uterus) during the menstrual cycle.
- High levels of estrogen before ovulation trigger the release of luteinizing hormone (LH), leading to ovulation.
B. Progesterone
- Progesterone is another important female reproductive hormone produced mainly by the corpus luteum after ovulation.
- Its primary role is to maintain the endometrium and prepare the uterus for implantation of the fertilized egg.
- It prevents uterine contractions to support pregnancy.
- If pregnancy does not occur, progesterone levels fall, leading to menstruation.
C. Luteinizing Hormone (LH)
- LH is a hormone produced by the anterior pituitary gland.
- A sudden increase in LH is known as the LH surge, which is the main cause of ovulation (rupture of Graafian follicle).
- In females, LH also stimulates the formation of the corpus luteum, which then secretes progesterone.
- In males, LH stimulates Leydig cells to produce testosterone.
D. Follicle-Stimulating Hormone (FSH)
- FSH is also produced by the anterior pituitary gland.
- It stimulates the growth and maturation of ovarian follicles in females.
- Works with estrogen to prepare the ovary for ovulation.
- In males, FSH stimulates the seminiferous tubules for sperm production.
Summary Table
Hormone Main Function Estrogen Builds endometrial lining and triggers LH surge Progesterone Maintains endometrium, supports early pregnancy Luteinizing Hormone (LH) Causes ovulation and forms corpus luteum Follicle Stimulating Hormone (FSH) Maturation of ovarian follicles