iPedia Free Information Center

Information about Ovarian Follicle

Human ovarian follicle
Latinfolliculi ovarici primarii, folliculi ovarici vesiculosi
subject #266 1256
Precursorcortical cords
MeSH Ovarian+Follicle
Dorlands/Elsevier f_11/12372180
Ovarian follicles are the basic unit of female reproductive biology, they are roughly spherical aggregations of cells found in the ovary. They contain a single oocyte (aka ovum or egg). These structures are periodically initiated to grow and develop, culminating in ovulation of usually a single competent oocyte.

Structure

Enlarge picture
Section of vesicular ovarian follicle of cat. X 50.


The cells of the ovarian follicle are the oocyte, granulosa cells and the cells of the internal and external theka layers.

Oocyte

The oocyte in a follicle is in the stage of a primary oocyte. The nucleus of such an oocyte is called a germinal vesicle[1] (see picture).

Granulosa

The oocyte is surrounded by a glycoprotein layer, the zona striata, or zona pellucida. This, in turn, is swaddled in a layer of granulosa cells. In early tertiary follicles, the granulosa cells connecting the oocyte to the rest of the granulosa cells (membrana granulosa are the discus proligerus or cumulus oophorus.

Theka

The granulosa cells, in turn, are enclosed in a thin layer of extracellular matrix – the follicular basement membrane or basal lamina (fibro-vascular coat in picture). Outside the basal lamina, the layers theka interna and theka externa are found.

Development

Main article: Folliculogenesis


Primordial follocles are undiscernible to the naked eye. However, they develop to primary, secondary and finally mature vesicular follicles. Mature vesicular follicles are sometimes called Graafian follicles (after Regnier de Graaf).

In humans, oocytes are established in the ovary before birth, and may lay dormant awaiting initiation for up to 50 years [2].

After rupturing, the follicle is turned into a corpus luteum.

Development of oocytes in ovarian follicles

Main article: Oogenesis
In a larger perspective, the whole folliculogenesis from primordial to preovulatory follicle is located in the stage of meiosis I of ootidogenesis in oogenesis.

The embryonic development doesn't differ from the male one, but follows the common path before gametogenesis. Once gametogonia enter the gonadal ridge, however, they attempt to associate with these somatic cells. Development proceeds and the gametogonia turns into oogonia, which become fully surrounded by a layer of cells (pre-granulosa cells).

Oogonia multiply by dividing mitotically; this proliferation ends when the oogonia enter meiosis. The amount of time that oogonia multiply by mitosis is species specific. In the human fetus, cells undergoing mitosis are seen until the second and third trimester of pregnancy [3]; [4]. After beginning the meiotic process, the oogonia (now called primary oocytes) can no longer replicate. Therefore the total number of gametes is established at this time. Once the primary oocytes stop dividing the cells enter a prolonged ‘resting phase’. This ‘resting phase’ or dictyate stage can last anywhere up to fifty years in the human.

For each primary oocyte that undergoes meiosis, only one functional oocyte is produced. The other two or three cells produced are called polar bodies. Polar bodies have no function and eventually deteriorate.

The primary oocyte turns into a secondary oocyte in mature ovarian follicles. Unlike the sperm, the egg is arrested in the secondary stage of meiosis until fertilization.

Upon fertilization by sperm, the secondary oocyte continues the second part of meiosis and becomes a zygote.

Pathology

Any ovarian follicle that is larger than about two centimeters is termed an ovarian cyst.

References

1. ^ Biology-online
2. ^ McGee, E. A., and Hsueh, A. J. (2000). Initial and cyclic recruitment of ovarian follicles. Endocrine Reviews 21, 200-14.
3. ^ Baker, T. G. (1982). Oogenesis and ovulation. In "Book 1: Germ cells and fertilization" (C. R. Austin and R. V. Short, Eds.), pp. 17-45. Cambridge University Press, Cambridge.
4. ^ Byskov, A. G., and Hoyer, P. E. (1988). Embryology of mammalian gonads and ducts. In "The physiology of reproduction" (E. Knobil and J. Neill, Eds.), pp. 265-302. Raven Press, Ltd, New York.

Additional images


Histology of the preovulatory follicle.

Pre-antral follicle

Graafian follicles


External links

 •  • [ e]
Female reproductive system
Ovaries/OogenesisGerminal epithelium • Tunica albuginea • cortex (Cumulus oophorus, Stroma) • Medulla
Follicles/Folliculogenesiscorpus (hemorrhagicum, luteum, albicans) • Theca folliculi (externa, interna) • Follicular antrum (Follicular fluid) • Corona radiata • Zona pellucida • Membrana granulosa (Granulosa cells)
LigamentsProper • Suspensory • Round • Broad (Mesovarium, Mesosalpinx, Mesometrium) • Cardinal
Fallopian tubesIsthmus • Ampulla • Infundibulum • Fimbria
Uteruscervix/neck (External orifice, Canal of the cervix, Internal orifice) • corpus/body (Cavity of the body, Fundus) • layers (Endometrium, Myometrium, Perimetrium)
VulvaMons pubis • Labium  (Labial commissures, Frenulum labiorum pudendi, Labia majora, Cleft of venus, Labia minora, Vulval vestibule, interlabial sulci) • Clitoris  (Clitoral hood , Clitoral glans, Frenulum clitoridis, Clitoral crura, Corpus cavernosa, Vestibular bulbs) • Vagina (Bartholin's glands, Bartholin's ducts, Skene's glands, Skene's ducts, Fossa of vestibule of vagina, Vaginal fornix, Hymen)
BreastMammary glands • Nipple • Areola • Lactiferous duct
OtherG-spot • Urethral sponge
Latin}}} 
Official status
Official language of: Vatican City
Used for official purposes, but not spoken in everyday speech
Regulated by: Opus Fundatum Latinitas
Roman Catholic Church
Language codes
ISO 639-1: la
ISO 639-2: lat
..... Click the link for more information.
Embryology is the study of the development of an embryo. An embryo is defined as any vertebrate in a stage before birth or hatching. Embryology refers to the development of the egg cell (zygote) after fertilization and the differentiation of cells into tissues and organs.
..... Click the link for more information.
In embryology, cortical cords (also called secondary cords) are structures that develop from sex cords in the female. After further development they become the ovarian follicles.
..... Click the link for more information.
Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed
..... Click the link for more information.
Elsevier, the world's largest publisher of medical and scientific literature, forms part of the Reed Elsevier group. Based in Amsterdam, the company has substantial operations in the UK, USA and elsewhere.
..... Click the link for more information.
Editing of this page by unregistered or newly registered users is currently disabled due to vandalism.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.
For ovary as part of plants see ovary (plants)
An ovary is an egg-producing reproductive organ found in female organisms. They are usually purple. It is often found in pairs as part of the vertebrate female reproductive system.
..... Click the link for more information.
An oocyte, ovocyte, or rarely oöcyte, is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum. An Oocyte is part the Ovary development, Different names for different stages.
..... Click the link for more information.
ovum (plural ova) is a haploid female reproductive cell or gamete. The word is derived from Latin, meaning egg or egg cell. Both animals and embryophytes have ova. The term ovule
..... Click the link for more information.
Ovulation is the process in the menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum (also known as an oocyte, female gamete, or casually, an egg) that participates in reproduction.
..... Click the link for more information.
An oocyte, ovocyte, or rarely oöcyte, is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum. An Oocyte is part the Ovary development, Different names for different stages.
..... Click the link for more information.
The zona pellucida (or zona striata in older texts) is a glycoprotein membrane surrounding the plasma membrane of an oocyte. It is a vital constitutive part of the latter, external but not extraneous to it.
..... Click the link for more information.
A granulosa cell is a somatic cell found closely associated with the developing female gamete (called an oocyte or egg) in the ovary of mammals.

Anatomy and function


..... Click the link for more information.
cumulus oophorus( Latin cumulus=heap Greek or oo=egg phorus=carrying)discus proligerus, and in it the ovum is imbedded.

External links

  • Organology at UC Davis Reproductive/mammal/ovary5/ovary3

..... Click the link for more information.
extracellular matrix (ECM) is the extracellular part of animal tissue that usually provides structural support to the cells in addition to performing various other important functions. The extracellular matrix is the defining feature of connective tissue in animals.
..... Click the link for more information.
folliculogenesis is the maturation of the ovarian follicle, a densely-packed shell of somatic cells that contains an immature oocyte. Folliculogenesis describes the progression of a number of small primordial follicles into large preovulatory follicles
..... Click the link for more information.
Regnier de Graaf (July 30, 1641 – August 17, 1673); first name is often spelled Reinier or Reynier, was a Dutch physician and anatomist.

Graff was born in Schoonhoven, Netherlands.
..... Click the link for more information.
The corpus luteum (Latin for "yellow body") (plural corpora lutea) is a temporary endocrine structure in mammals, involved in the production of the progestogens which are needed for the maintenance of a pregnancy.
..... Click the link for more information.
Oogenesis or rarely oögenesis is the creation of an ovum (egg cell). It is the female process of gametogenesis. It involves the various stages of immature ova.

Oogenesis in mammals

In mammals, oogenesis occurs in the ovarian follicle of the ovary.
..... Click the link for more information.
This article or section is in need of attention from an expert on the subject.
Please help recruit one or [ improve this article] yourself. See the talk page for details.
..... Click the link for more information.
Gametogenesis is a process by which the diploid germ cells undergo a number of chromosomal and morphological changes to form mature haploid gametes. Depending on the biological life cycle of the organism, gametogenesis occurs by meiotic division of gametocytes into various gametes
..... Click the link for more information.
In embryology, the gonadal ridge (or genital ridge) is the precursor to the gonads. The gonadal ridge initially consists mainly of mesenchyme and cells of underlying mesonephric origin. Once oogonia enter this area they attempt to associate with these somatic cells.
..... Click the link for more information.
A granulosa cell is a somatic cell found closely associated with the developing female gamete (called an oocyte or egg) in the ovary of mammals.

Anatomy and function


..... Click the link for more information.
The dictyate or dictyotene[1] is a prolonged resting phase in oogenesis. It occurs in the stage of meiotic prophase I[2]. It starts late in fetal life[2] and is terminated shortly before ovulation.
..... Click the link for more information.
Polar body is a cell structure found inside an ovum. Both animal and plant ova possess it.

Asymmetrical cell division (cytokinesis) leads to the production of polar bodies during oogenesis.
..... Click the link for more information.
For other meanings see Zygote (disambiguation).
A zygote (Greek: ζυγωτόν) is a cell that is the result of fertilization.
..... Click the link for more information.
1 centimetre =
SI units
010−3 m 0 mm
US customary / Imperial units
010−3 ft 0 in
A centimetre (American spelling: centimeter, symbol cm
..... Click the link for more information.
Benign ovarian cyst. Most of the native ovary has been displaced by the cyst. The white oval at the 8 o'clock position is a Corpus albicans, the old remnant of a corpus luteum. The Fallopian tube runs over the top of the cyst, with the fimbriae at the top left of the image.
..... Click the link for more information.
The State University of New York Health Science Center at Brooklyn, better known as SUNY Downstate Medical Center, is an academic medical center and is the only one of its kind in the Borough of Brooklyn in New York City.
..... Click the link for more information.
Boston University (BU) is a private research university located in Boston, Massachusetts, United States. Although chartered by the Massachusetts Legislature in 1869, Boston University traces its roots to the establishment of the Newbury Biblical Institute in Newbury,
..... Click the link for more information.


This article is copied from an article on Wikipedia.org - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the wikipedia encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License.
Herod_Archelaus


page counter