ovarian follicle

(noun)

The basic units of female reproductive biology, each composed of roughly spherical aggregations of cells found in the ovary.

Related Terms

  • fallopian tubes
  • oviduct

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.
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