Graafian follicle

a fluid-filled vesicle in the mammalian ovary containing a developing egg cell

Graafian Follicle

(named after R. de Graaf), a mul-tilayered saclike follicle that develops in the cortical layer of the ovary of mammals, including humans, under the influence of the follicle-stimulating hormone. The wall of the Graafian follicle consists of an external layer of connective tissue, under which is the multilayered follicular epithelium lining the Graafian follicle cavity, which is filled with a serous liquid. The epithelium forms a process into the Graafian follicle cavity (cumulus oophorus), in which the ovum is located, and provides it with nutrients. The developing follicle produces the hormone estrogen, which prepares the sexual ducts to receive the egg after ovulation, that is, its release from the Graafian follicle and the ovary. The ovulated egg enters the oviduct, where it can join with a spermatozoon and be fertilized. In animals that bear many young at once, several Graafian follicles grow and mature simultaneously.

D. A. POTEMKINA

Graafian follicle

[′gräf·ē·ən ′fäl·ə·kəl] (histology) The mature mammalian ovum with its surrounding epithelial cells.

Graafian follicle

graafian follicle

[graf´e-an] a small sac, embedded in the ovary, that encloses an ovum. At puberty each ovary has a large number of immature follicles (follicles" >primordial follicles), each of which contains an undeveloped egg cell.
About every 28 days between puberty and the onset of menopause, one of the follicles develops to maturity, or ripens, into a graafian follicle (or vesicular ovarian follicle). As it ripens, it increases in size. The ovum within becomes larger, the follicular wall becomes thicker, and fluid collects in the follicle and surrounds the ovum. The follicle also secretes estradiol, the hormone that prepares the endometrium to receive a fertilized egg. As the follicle matures, it moves to the surface of the ovary and forms a projection. When fully mature, the graafian follicle breaks open and releases the ovum, which passes into the fallopian tubes. This release of the ovum is called ovulation; it occurs midway in the menstrual cycle, generally about 14 days after the commencement of the menstrual flow.
The released ovum travels down the tube to the uterus, a process that takes about 3 days. Meanwhile, the empty graafian follicle in the ovary becomes filled with cells containing a yellow substance, the corpus luteum. The corpus luteum secretes progesterone, a hormone that causes further change in the endometrium, allowing it to provide a good milieu in which a zygote (fertilized ovum) can grow through the stages of gestation to become a fetus.

ve·sic·u·lar o·var·i·an fol·li·cle

[TA] a follicle in which the primary oocyte attains its full size and is surrounded by an extracellular glycoprotein layer (zona pellucida) that separates it from a peripheral layer of follicular cells permeated by one or more fluid-filled antra; the primary oocyte occupies the cumulus oophorus; the theca of the follicle develops into internal and external layers. Synonym(s): folliculus ovaricus vesiculosus [TA], antral follicle, graafian follicle, secondary ovarian follicle, vesicular follicle

Graafian follicle

(grä′fē-ən, grăf′ē-)n. Any of the fluid-filled vesicles in the mammalian ovary containing a maturing ovum.

ve·sic·u·lar o·var·i·an fol·li·cle

(vĕ-sik'yū-lăr ō-var'ē-ăn fol'i-kĕl) [TA] A follicle in which the oocyte attains its full size and is surrounded by an extracellular glycoprotein layer (zona pellucida) that separates it from a peripheral layer of follicular cells permeated by one or more fluid-filled antra; the theca of the follicle develops into internal and external layers.
Synonym(s): antral follicle, graafian follicle, secondary follicle.

Graafian follicle

A nest of cells in the ovary that develops into a fluid-filled cyst containing a maturing egg (ovum). One or more of these develops in each menstrual cycle, releasing one or more ova into the FALLOPIAN TUBE and leaving behind the CORPUS LUTEUM. (Regnier de Graaf, 1641–73, Dutch anatomist).

Fig. 179 Graafian follicle . General structure.

Graafian follicle

a structure in the ovary of a female mammal, consisting of an OOCYTE surrounded by granular FOLLICLE cells which enclose also a large, fluid filled cavity, the whole structure being encased in a wall of connective tissue. See Fig. 179 . The Graafian follicle begins to form deep inside the ovary, stimulated by FSH as the OESTROUS CYCLE develops, gradually enlarging and maturing as it moves to the surface, eventually appearing like a blister on the surface, just prior to release of the oocyte (ovulation) by rupture of the wall. After ovulation the follicle becomes a CORPUS LUTEUM. Further ovulation is normally prevented by the corpus luteum secreting PROGESTERONE, which in turn inhibits FSH production by the PITUITARY GLAND, so no further follicles develop. The presence of the cavity distinguishes the Graafian follicle (named after Regnier de Graaf) from the OVARIAN FOLLICLES of other vertebrates.

Graaf,

Reijnier de, Dutch physiologist and histologist, 1641-1673. graafian follicle - a follicle in which the oocyte attains its full size. Synonym(s): vesicular ovarian follicle

Graafian follicle

Graaf·i·an follicle

Graafian follicle

Graaf′i•an fol′licle

Graafian follicle

Graafian follicle

Graafian follicle

Graafian Follicle

Graafian follicle

Graafian follicle

graafian follicle

ve·sic·u·lar o·var·i·an fol·li·cle

Graafian follicle

ve·sic·u·lar o·var·i·an fol·li·cle

Graafian follicle

Graafian follicle

Graaf,

Graafian follicle

Words related to Graafian follicle

noun a vascular body in a mammalian ovary enclosing a developing egg

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