Ovulation - Nucleus Health

Summary

Ovulation is a crucial part of the menstrual cycle where a mature egg is released from the ovary. This process occurs around day 14 of a typical 28-day cycle, following a surge in luteinizing hormone. The cycle begins with the growth of multiple follicles, but only one becomes dominant and continues to mature. As the dominant follicle bursts, it releases the egg, which is then captured by the fallopian tube. If fertilized within 12-24 hours, pregnancy may occur; otherwise, the egg disintegrates and is shed during menstruation.

Takeaways

• 😀 Ovulation is part of the menstrual cycle when the ovary releases a mature egg.
• 😀 The ovary contains hundreds of thousands of follicles, each housing an immature egg.
• 😀 During the first 7 days of the cycle, a few follicles begin to grow and secrete estrogen.
• 😀 Estrogen prepares the uterus for potential pregnancy by thickening the uterine lining.
• 😀 Around Day 7, most follicles stop growing and degenerate, leaving one dominant follicle.
• 😀 The dominant follicle continues to grow, nourishing the egg inside it.
• 😀 Around Day 12, the dominant follicle secretes a large amount of estrogen, triggering the pituitary gland to release luteinizing hormone.
• 😀 The luteinizing hormone surge causes the follicle to undergo a rapid growth spurt around Day 14.
• 😀 Just before ovulation, the egg detaches from the follicle, and the follicle bursts, releasing the egg into the abdominal cavity.
• 😀 The fimbriae at the end of the fallopian tube sweep the egg into the tube, where it is transported toward the uterus.
• 😀 The egg survives for 12-24 hours post-ovulation, during which it must be fertilized by sperm for pregnancy to occur.

Q & A

What is ovulation?

Ovulation is the process in the menstrual cycle when the ovary releases a mature egg (ovum), making it available for fertilization.

How many follicles are present in the ovaries?

The ovaries contain hundreds of thousands of follicles, each containing an immature egg at the center.

What happens to the follicles during the menstrual cycle?

At the beginning of the menstrual cycle, a few follicles begin to grow. As the cycle progresses, all but one of these follicles degenerate, and the dominant follicle continues to grow and nourish the egg inside.

What role does estrogen play during the menstrual cycle?

Estrogen, secreted by the maturing follicles, helps prepare the uterine lining for a possible pregnancy.

When does the dominant follicle begin to secrete estrogen, and what is its effect?

Around Day 12 of the menstrual cycle, the dominant follicle secretes a large amount of estrogen, signaling the hypothalamus and pituitary gland to release luteinizing hormone (LH).

What is luteinizing hormone (LH), and why is it important?

Luteinizing hormone (LH) is released by the pituitary gland in response to estrogen. It triggers the final maturation of the dominant follicle and causes ovulation.

What happens during ovulation?

During ovulation, the dominant follicle bursts open, releasing the egg and surrounding fluid into the abdominal cavity. The fallopian tube then picks up the egg using fimbriae, tiny projections at the end of the tube.

How does the egg travel through the fallopian tube after ovulation?

After ovulation, microscopic cilia on the fimbriae of the fallopian tube move the egg into the tube, and muscular contractions push the egg toward the uterus.

How long does the egg remain viable for fertilization after ovulation?

The egg remains viable for fertilization for 12 to 24 hours after ovulation. If it is not fertilized during this time, it will dissolve and be shed during menstruation.

What happens if the egg is not fertilized?

If the egg is not fertilized, it dissolves and is eventually expelled from the body along with the uterine lining during menstruation.