Follicular Phase

Definition

The follicular phase is the first stage of the menstrual cycle, occurring between the end of the previous menstrual period and ovulation. During this phase, the ovarian follicles mature and the uterine lining thickens in preparation for implantation.

5 Must Know Facts For Your Next Test

1. The follicular phase is typically the longest phase of the menstrual cycle, lasting approximately 10-14 days.
2. During the follicular phase, the pituitary gland releases follicle-stimulating hormone (FSH), which stimulates the growth and development of several ovarian follicles.
3. One of these follicles will become the dominant follicle, which will eventually release the mature egg during ovulation.
4. As the follicles grow, they produce increasing amounts of the hormone estrogen, which causes the uterine lining to thicken and become more receptive to implantation.
5. The end of the follicular phase is marked by a surge in luteinizing hormone (LH) from the pituitary gland, which triggers the release of the mature egg from the dominant follicle.

Review Questions

• Describe the key events that occur during the follicular phase of the menstrual cycle.
  • During the follicular phase, the pituitary gland releases follicle-stimulating hormone (FSH), which stimulates the growth and development of several ovarian follicles. One of these follicles becomes the dominant follicle, which produces increasing amounts of the hormone estrogen. This estrogen causes the uterine lining to thicken and become more receptive to implantation. The end of the follicular phase is marked by a surge in luteinizing hormone (LH), which triggers the release of the mature egg from the dominant follicle in a process called ovulation.
• Explain the role of the ovarian follicles and estrogen during the follicular phase.
  • During the follicular phase, the ovarian follicles undergo maturation and growth, stimulated by follicle-stimulating hormone (FSH) from the pituitary gland. As the follicles grow, they produce increasing amounts of the hormone estrogen. This estrogen plays a crucial role in the follicular phase by causing the uterine lining to thicken and become more receptive to implantation. The dominant follicle, which will eventually release the mature egg, produces the highest levels of estrogen during this phase.
• Analyze the relationship between the follicular phase and the subsequent stages of the menstrual cycle.
  • The follicular phase sets the stage for the rest of the menstrual cycle. The growth and development of the ovarian follicles, as well as the increasing production of estrogen, directly influence the timing and events of the subsequent stages. The surge in luteinizing hormone (LH) at the end of the follicular phase triggers ovulation, marking the transition to the luteal phase. The thickened uterine lining, prepared during the follicular phase, is then maintained during the luteal phase to support potential implantation and pregnancy. The cyclical nature of the menstrual cycle is dependent on the coordinated events that occur during the follicular phase.

Related terms

Menstrual Cycle:

The cyclic changes in the female reproductive system, including the ovaries and uterus, that occur approximately every 28 days and enable pregnancy.

Ovulation:

The release of a mature egg from the ovary, which occurs around the midpoint of the menstrual cycle and is essential for fertility.

Luteal Phase:

The second half of the menstrual cycle, occurring after ovulation and lasting until the next menstrual period, during which the uterine lining is maintained.