ovarian follicle

Examples of ovarian follicle in the following topics:

• Hormonal Regulation of the Female Reproductive Cycle

  • The rise in FSH recruits tertiary-stage ovarian follicles (antral follicles) for entry into the menstrual cycle.
  • Follicle-stimulating hormone induces the proliferation of granulosa cells in the developing follicles and the expression of luteinizing hormone (LH) receptors on these cells.
  • Ovulation is the process in a female's menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum (oocyte).
  • In the preovulatory phase of the menstrual cycle, the ovarian follicle undergoes cumulus expansion stimulated by FSH.
  • The ovum then leaves the follicle through the formed stigma.

• Ovarian Cysts

  • An ovarian cyst is a fluid-filled vacuole within or on an ovary.
  • Any ovarian follicle that is larger than about two centimeters is termed an ovarian cyst.
  • Ovarian cysts affect women of all ages.
  • Some ovarian cysts cause problems, such as bleeding and pain.
  • About 95% of ovarian cysts are benign .

• Ovarian Cycle

  • The rise in FSH levels recruits five to seven tertiary-stage ovarian follicles (also known as Graafian or antral follicles) for entry into the menstrual cycle.
  • These follicles compete with each other for dominance.
  • This slowdown in LH and FSH production leads to the atresia (death) of most of the recruited follicles, though the dominant follicle continues to mature.
  • Ovulation is the phase in which a mature ovarian follicle ruptures and discharges an ovum (also known as an oocyte, female gamete, or egg).
  • The ovarian cycle is the series of changes that occur in the ovary during the menstrual cycle that cause maturation of a follicle, ovulation, and development of the corpus luteum.

• Female Duct System

  • When an ovum is developing in an ovary, it is encapsulated in a sac known as an ovarian follicle.
  • On maturation, the follicle and the ovary's wall rupture, allowing the ovum to escape.

• Ovaries

  • The ovaries are located in the lateral wall of each side of the pelvis in a region called the ovarian fossa.
  • The uterine extremity points downward and is attached to the uterus via the ovarian ligament.
  • The developing egg cell (or oocyte) grows within the environment provided by ovarian follicles.
  • Follicles are composed of different types and number of cells according to their maturation stage, which can be determined by their size.
  • When oocyte maturation is completed, a luteinizing hormone (LH) surge secreted by the pituitary gland stimulates follicle rupture and oocyte release.

• Female Hormones

  • The stages of the ovarian cycle in the female are regulated by hormones secreted by the hypothalamus, pituitary, and the ovaries.
  • The first half of the ovarian cycle is the follicular phase.
  • The follicles that did not rupture degenerate and their eggs are lost.
  • The level of estrogen decreases when the extra follicles degenerate.
  • Rising and falling hormone levels result in progression of the ovarian and menstrual cycles.

• Male and Female Gonads

  • The ovary is a paired, ovum-producing, reproductive organ located in the lateral wall of the pelvis in a region called the ovarian fossa.
  • The ovaries are not attached to the fallopian tubes but to the outer layer of the uterus via the ovarian ligaments.
  • Prior to ovulation, follicle-stimulating hormone is secreted by the granulosal cells that convert testosterone into estradiol.
  • The presence of both testosterone and follicle-stimulating hormone is needed to support spermatogenesis.
  • The left ovary is visible above the label ovarian arteries.

• Ovarian Cancer

  • Ovarian cancer arises from the epithelial layer of the ovary and in some cases, the fallopian tube.
  • Ovarian cancer is a cancerous growth arising from the ovary.
  • In most cases, the exact cause of ovarian cancer remains unknown.
  • The risk of developing ovarian cancer appears to be affected by several factors.
  • The more children a woman has, the lower her risk of ovarian cancer.

• Oogenesis

  • Follicle development signals the beginning of the menstrual cycle.
  • At the start of the menstrual cycle, some 12-20 primary follicles begin to develop under the influence of elevated levels of follicle-stimulating hormone (FSH) to form secondary follicles.
  • The primary follicles form from primordial follicles, which develop in the ovary as a fetus during conception and are arrested in the prophase state of the cellular cycle.
  • The remaining follicle, called the dominant follicle, is responsible for producing large amounts of estrogen during the late follicular phase.
  • This causes the secondary follicle to develop into a tertiary follicle, which then leaves the ovary 24–36 hours later.

• Infertility

  • In this case synthetic FSH by injection or Clomid (Clomiphene citrate) via a pill can be given to stimulate follicles to mature in the ovaries.
  • If the sperm are of good quality and the mechanics of the woman's reproductive structures are good (patent fallopian tubes, no adhesions or scarring), physicians may start by prescribing a course of ovarian stimulating medication.