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Corpus luteum

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Corpus luteum
Section of the ovary. 1. Outer covering. 1’. Attached border. 2. Centralstroma.3. Peripheral stroma. 4. Bloodvessels. 5. Vesicular follicles in their earliest stage. 6, 7, 8. More advanced follicles. 9. An almost mature follicle. 9’. Follicle from which the ovum has escaped. 10.Corpus luteum.
Details
SystemReproductive system
LocationOvary
Identifiers
Latincorpus luteum
MeSHD003338
TA98A09.1.01.015
TA23484
FMA18619
Anatomical terms of microanatomy

Thecorpus luteum(Latinfor "yellow body";pl.:corpora lutea) is a temporaryendocrinestructure in femaleovariesinvolved in the production of relatively high levels ofprogesterone,and moderate levels ofestradiol,andinhibin A.[1][2]It is the remains of the ovarian follicle that has released a mature ovum during a previous ovulation.[3]

The corpus luteum is colored as a result of concentratingcarotenoids(includinglutein) from the diet and secretes a moderate amount ofestrogenthat inhibits further release ofgonadotropin-releasing hormone(GnRH) and thus secretion ofluteinizing hormone(LH) andfollicle-stimulating hormone(FSH). A new corpus luteum develops with eachmenstrual cycle.

Development and structure

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The corpus luteum develops from anovarian follicleduring theluteal phaseof themenstrual cycleoroestrous cycle,following the release of a secondary oocyte from the follicle duringovulation.The follicle first forms acorpus hemorrhagicumbefore it becomes a corpus luteum, but the term refers to the visible collection of blood, left after rupture of the follicle, that secretes progesterone. While theoocyte(later thezygoteif fertilization occurs) traverses thefallopian tubeinto theuterus,the corpus luteum remains in theovary.[citation needed]

The corpus luteum is typically very large relative to the size of the ovary; in humans, the size of the structure ranges from under 2 cm to 5 cm in diameter.[4]

Its cells develop from the follicular cells surrounding the ovarian follicle.[5]The folliculartheca cellsluteinize into small luteal cells (thecal-lutein cells) and folliculargranulosa cellsluteinize into large luteal cells (granulosal-lutein cells) forming the corpus luteum. Progesterone is synthesized from cholesterol by both the large and small luteal cells upon luteal maturation. Cholesterol-LDLcomplexes bind to receptors on the plasma membrane of luteal cells and are internalized. Cholesterol is released and stored within the cell as cholesterol ester. LDL is recycled for further cholesterol transport. Large luteal cells produce more progesterone due to uninhibited/basal levels ofprotein kinase A(PKA) activity within the cell. Small luteal cells have LH receptors that regulate PKA activity within the cell. PKA actively phosphorylatessteroidogenic acute regulatory protein(StAR) andtranslocator proteinto transport cholesterol from the outer mitochondrial membrane to the inner mitochondrial membrane.[6]

The development of the corpus luteum is accompanied by an increase in the level of the steroidogenic enzymeP450sccthat converts cholesterol topregnenolonein the mitochondria.[7]Pregnenolone is then converted to progesterone that is secreted out of the cell and into the blood stream. During the bovine estrous cycle, plasma levels of progesterone increase in parallel to the levels of P450scc and its electron donor adrenodoxin, indicating that progesterone secretion is a result of enhanced expression of P450scc in the corpus luteum.[7]

The mitochondrial P450 system electron transport chain includingadrenodoxin reductaseandadrenodoxinhas been shown to leak electrons leading to the formation of superoxide radical.[8][9]Apparently to cope with the radicals produced by this system and by enhanced mitochondrial metabolism, the levels of antioxidant enzymes catalase and superoxide dismutase also increase in parallel with the enhanced steroidogenesis in the corpus luteum.[7]

Follicular structure Luteal structure Secretion
Theca cells Theca lutein cells androgens,[10]progesterone[10]
Granulosa cells Granulosa lutein cells progesterone,[5]estrogen(majority),[5]andinhibin A[5][10]
Steroidogenesis,withprogesteronein yellow field at upper center.[11]Theandrogensare shown in blue field, andaromataseat lower center – the enzyme present in granulosa lutein cells that convert androgens intoestrogens(shown in pink triangle).

Like the previous theca cells, the theca lutein cells lack thearomataseenzyme that is necessary to produce estrogen, so they can only performsteroidogenesisuntil formation ofandrogens.The granulosa lutein cells do have aromatase, and use it to produce estrogens, using the androgens previously synthesized by the theca lutein cells, as the granulosa lutein cells in themselves do not have the17α-hydroxylaseor17,20 lyaseto produce androgens.[5] Once the corpus luteum regresses the remnant is known ascorpus albicans.[12]

Function

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The corpus luteum is essential for establishing and maintaining pregnancy in females. The corpus luteum secretesprogesterone,which is asteroid hormoneresponsible for thedecidualizationof theendometrium(its development) and maintenance, respectively. It also producesrelaxin,a hormone responsible for softening of thepubic symphysiswhich helps in parturition.[13]

Unsuccessful fertilisation

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If the egg is not fertilised, the corpus luteum stops secreting progesterone and decays (after approximately 10 days in humans). It then degenerates into acorpus albicans,which is a mass of fibrousscartissue.[14]

With cessation of progesterone release, the uterine lining (functional, inner layer of the endometrium) is expelled through the vagina (in mammals that go through amenstrual cycle). Across anestrous cycle,the functional layer regenerates to provide nourishing tissue for potential fertilisation and implantation.[15][16]

Successful fertilisation

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Vaginal ultrasoundshowing a corpus luteum in a pregnant woman, with a fluid-filled cavity in its center

If the egg is fertilised andimplantationoccurs, the syncytiotrophoblast (derived fromtrophoblast) cells of theblastocystsecrete the hormonehuman chorionic gonadotropin(hCG, or a similar hormone in other species) by day 9 post-fertilisation.[citation needed]

Human chorionic gonadotropin signals the corpus luteum to continue progesterone secretion, thereby maintaining the thick lining (endometrium) of the uterus and providing an area rich inblood vesselsin which thezygote(s) can develop. From this point on, the corpus luteum is called thecorpus luteum graviditatis.[17]

The introduction ofprostaglandinsat this point causes the degeneration of the corpus luteum and theabortionof thefetus.However, in placental animals such as humans, theplacentaeventually takes over progesterone production and the corpus luteum degrades into acorpus albicanswithout embryo/fetus loss.[citation needed]

Luteal supportrefers to the administration of medication (generallyprogestins) for the purpose of increasing the success ofimplantationand earlyembryogenesis,thereby complementing the function of the corpus luteum.

Content of carotenoids

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The yellow color and name of the corpus luteum, like that of themacula luteaof the retina, is due to its concentration of certaincarotenoids,especiallylutein.In 1968, a report indicated that beta-carotene was synthesized in laboratory conditions in slices of corpus luteum from cows. However, attempts have been made to replicate these findings, but have not succeeded. The idea is not presently accepted by the scientific community.[18]Rather, the corpus luteum concentrates carotenoids from the diet of the mammal.

In animals

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Similar structures and functions of the corpus luteum exist in some reptiles.[19]Dairy cattle also follow a similar cycle.[20]

Additional images

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  • Order of changes in ovary
    Order of changes in ovary
  • Human ovary with fully developed corpus luteum
    Human ovary with fully developed corpus luteum
  • Luteinized follicular cyst. H&E stain.
    Luteinized follicular cyst.H&E stain.

Pathology

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  • Corpus luteum cyst:hemorrhage into persistent corpus luteum. Commonly regresses spontaneously.

See also

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References

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  1. ^"Histology Laboratory Manual".www.columbia.edu.Archivedfrom the original on 6 May 2017.Retrieved3 May2018.
  2. ^Inquiry Into Biology(Textbook). McGraw-Hill Ryerson. 2007. p. 497.ISBN978-0-07-096052-7.
  3. ^Karch 2017,p. 657.
  4. ^Vegetti W, Alagna F (2006)."FSH and follucogenesis: from physiology to ovarian stimulation".Reproductive biomedicine Online.Archivedfrom the original on 2011-07-15.Retrieved2009-05-26.
  5. ^abcdeBoron 2005,p. 1300.
  6. ^Niswender GD (March 2002)."Molecular control of luteal secretion of progesterone".Reproduction.123(3): 333–9.doi:10.1530/rep.0.1230333.PMID11882010.
  7. ^abcRapoport R, Sklan D, Wolfenson D, Shaham-Albalancy A, Hanukoglu I (March 1998)."Antioxidant capacity is correlated with steroidogenic status of the corpus luteum during the bovine estrous cycle".Biochim. Biophys. Acta.1380(1): 133–40.doi:10.1016/S0304-4165(97)00136-0.PMID9545562.
  8. ^Hanukoglu I, Rapoport R, Weiner L, Sklan D (September 1993)."Electron leakage from the mitochondrial NADPH-adrenodoxin reductase-adrenodoxin-P450scc (cholesterol side chain cleavage) system".Arch. Biochem. Biophys.305(2): 489–98.doi:10.1006/abbi.1993.1452.PMID8396893.
  9. ^Rapoport R, Sklan D, Hanukoglu I (March 1995)."Electron leakage from the adrenal cortex mitochondrial P450scc and P450c11 systems: NADPH and steroid dependence".Arch. Biochem. Biophys.317(2): 412–6.doi:10.1006/abbi.1995.1182.PMID7893157.
  10. ^abcThe IUPS Physiome Project --> Female Reproductive System – CellsArchived2009-12-10 at theWayback MachineRetrieved on Nov 9, 2009
  11. ^Häggström, Mikael; Richfield, David (2014)."Diagram of the pathways of human steroidogenesis".WikiJournal of Medicine.1(1).doi:10.15347/wjm/2014.005.ISSN2002-4436.
  12. ^Marieb, Elaine (2013).Anatomy & physiology.Benjamin-Cummings. p. 915.ISBN9780321887603.
  13. ^Wang, Yan; Li, Yong-Qiang; Tian, Mei-Rong; Wang, Nan; Zheng, Zun-Cheng (2021-01-06)."Role of relaxin in diastasis of the pubic symphysis peripartum".World Journal of Clinical Cases.9(1): 91–101.doi:10.12998/wjcc.v9.i1.91.ISSN2307-8960.PMC7809669.PMID33511175.
  14. ^Kirkendoll, Shelbie D.; Bacha, Dhouha (2023),"Histology, Corpus Albicans",StatPearls,Treasure Island (FL): StatPearls Publishing,PMID31424854,retrieved2023-11-16
  15. ^Critchley, Hilary O. D.; Babayev, Elnur; Bulun, Serdar E.; Clark, Sandy; Garcia-Grau, Iolanda; Gregersen, Peter K.; Kilcoyne, Aoife; Kim, Ji-Yong Julie; Lavender, Missy; Marsh, Erica E.; Matteson, Kristen A.; Maybin, Jacqueline A.; Metz, Christine N.; Moreno, Inmaculada; Silk, Kami (November 2020)."Menstruation: science and society".American Journal of Obstetrics and Gynecology.223(5): 624–664.doi:10.1016/j.ajog.2020.06.004.ISSN1097-6868.PMC7661839.PMID32707266.
  16. ^Campo, Hannes; Murphy, Alina; Yildiz, Sule; Woodruff, Teresa; Cervelló, Irene; Kim, J. Julie (July 2020)."Microphysiological Modeling of the Human Endometrium".Tissue Engineering. Part A.26(13–14): 759–768.doi:10.1089/ten.tea.2020.0022.ISSN1937-335X.PMC7398432.PMID32348708.
  17. ^Oliver, Rebecca; Pillarisetty, Leela Sharath (2023),"Anatomy, Abdomen and Pelvis, Ovary Corpus Luteum",StatPearls,Treasure Island (FL): StatPearls Publishing,PMID30969526,retrieved2023-11-16
  18. ^Brian Davis. Carotenoid metabolism as a preparation for function. Pure and Applied Chemistry, Vol. 63, No. 1, pp. 131–140, 1991.available online.Archived2011-07-26 at theWayback MachineAccessed April 30, 2010.
  19. ^Trauth, Stanley E. (1978). "Ovarian Cycle of Crotaphytus collaris (Reptilia, Lacertilia, Iguanidae) from Arkansas with Emphasis on Corpora Albicantia, Follicular Atresia, and Reproductive Potential".Journal of Herpetology.12(4): 461–470.doi:10.2307/1563350.ISSN0022-1511.JSTOR1563350.
  20. ^Dairy cattle fertility & sterility.Fort Atkinson, Wis: W.D. Hoard & Sons. 1996.ISBN978-0932147271.{{cite book}}:|work=ignored (help)

Bibliography

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  • Karch, Amy (2017).Focus on nursing pharmacology.Philadelphia: Wolters Kluwer.ISBN9781496318213.
  • Boron, Walter (2005).Medical physiology: a cellular and molecular approach.Philadelphia, Penns: Elsevier Saunders.ISBN1-4160-2328-3.
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