Endocrine Development Hormone from hormon (Gk) to Table of Contents| ... Hormones Produced by endocrine glands – ductless glands that secrete hormones into the ... secreted by the magnocellular

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  • EndocrineDevelopmentHormone from hormon (Gk) to set in motion, to urge on (E.H. Starling 1866-1927)

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  • Objectives

    Understandingofhormonetypes Focusonhypothalamusandpituitarydevelopment Understandingofendocrineglanddevelopment Understandingofendocrinedevelopmentalfunctions Briefunderstandingofmolecularregulationandsignalling

    mechanisms

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  • Citation: TheDevelopingHuman:clinicallyorientedembryology9th ed.KeithL.Moore,T.V.N.Persaud,MarkG.Torchia.Philadelphia,PA:Saunders,2011.Chapter9 PharyngealApparatus,Face,andNeckChapter12 UrogenitalSystem

    Citation: Larsen'shumanembryology4thed.Schoenwolf,GaryC;Larsen,WilliamJ,(WilliamJames).Philadelphia,PA :Elsevier/ChurchillLivingstone,c2009.Chapter16 DevelopmentofthePharyngealApparatusandFaceChapter15 DevelopmentoftheUrogenitalSystem

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    Nussey,S.andWhitehead,S.(2001).Endocrinology AnIntegratedApproach.UKOxford:BIOSScientificPublishers.ISBN10:1859962521.DetailedTableofContents |BookshelfLinkChapter1.PrinciplesofendocrinologyChapter2.TheendocrinepancreasChapter3.ThethyroidglandChapter4.TheadrenalglandChapter5.TheparathyroidglandsandvitaminDChapter6.ThegonadChapter7.ThepituitaryglandChapter8.Cardiovascularandrenalendocrinology

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    Hormones

    Producedbyendocrineglands ductlessglandsthatsecretehormonesintotheblood

    Aminoacidderivatives noradrenaline(norepinephrin),adrenalin(epinephrin),thyroidhormone

    Peptidesandproteins Thyroidstimulatinghormone,leutenising hormone,folliclestimulatinghormone(HPGaxis)

    Steroids androgens,glucocorticoids(regulateinflammation),mineralocorticoids(saltandwaterbalance)

    Allhormonesactuponcellsindifferenttissuesandcanbeclassifiedbythe"distance"oftheiraction,theclassicaldescriptionisthathormonesaredeliveredbytheblood.

    Autocrine actsonself(extracellularfluid) e.g.cytokinessuchasinterleukin1inmonocytes Paracrine actslocally(extracellularfluidorblood) e.g.fgf,Wnt,shh, Endocrine actsbysecretionintobloodstream(endocrineorgansarerichlyvascularized).

    HormoneReceptors cellsurface modifiedaminoacids,peptides,proteins e.g.FSHreceptor,Gproteincoupled

    receptor intracellularcytoplasmic/nuclear steroids androgenreceptor,Nuclearreceptorsubfamily

    3,C4(NR3C4)

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    Thepinealisaconeshapeddiverticulumoftheroofofthediencephalon

    Pineconeshaped Secretesmelatonin Producedbypinealocytes Inputfromvisualsystem Hasaroleintheinhibitionof

    gonadotrophichormoneswhenitisdamaged,prematurepubertyensues.

    Diminishesafterpuberty Notisolatedbytheblood

    brainbarrier richvasculature

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    Positionoftheadultpinealgland

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    Thehypothalamus controlsanteriorpituitaryandformstheposteriorpituitaryHormones Thyrotrophin releasinghormone(TRH),Corticotrophinreleasinghormone(CRH),Argininevasopressin(AVP),Gonadotrophin releasinghormone(GnRH),Growthhormonereleasinghormone(GHRH),Somatostatin,Prolactinrelasing factor(PRF),Dopamine

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    Thehypothalamus controlsanteriorpituitaryandformstheposteriorpituitaryHormones Thyrotrophin releasinghormone(TRH),Corticotrophinreleasinghormone(CRH),Argininevasopressin(AVP),Gonadotrophin releasinghormone(GnRH),Growthhormonereleasinghormone(GHRH),Somatostatin,Prolactinrelasing factor(PRF),Dopamine

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    Abbreviations:AHA,anteriorhypothalamicarea;AR,arcuate nucleus;DMN,dorsomedial nucleus;MB,mammillarybody;ME,medianeminence;MN,medialnucleus;OC,opticchiasm;PHN,posteriorhypothalamicnucleus;POA,preoptic area;PVN,paraventricularnucleus;SCN,suprachiasmatic nucleus;SO,supraoptic nucleus;VMN,ventromedialnucleus

    Endocrinology:AnIntegratedApproach.Nussey S,WhiteheadS.Oxford:BIOSScientificPublishers;2001

    Thenucleiofthehypothalamus

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    Pituitarydevelopmentmovie Interactionbetweenthefloorofthediencephalonandtheectodermalroofofthestomadeum

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    Rathkes pouch thehypophysial diverticulum formstheanteriorlobeevidentat45weeksThedowngrowth oftheneuroectoderm theneurohypophysial diverticulumformstheposteriorlobe

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    Pituitarydevelopmentlate

    Connectionwiththeoralcavityislostasthesphenoidbonedevelopsaspartofthechondocranium atthebaseoftheskull.Thepituitarybecomesencasedinthesella turcica(turkish saddle)

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    Pituitarydevelopmenttimeline

    Week4 hypophysial pouch,Rathkes pouch,diverticulumfromroofWeek5 elongation,contactsinfundibulum,diverticulumofdiencephalonWeek6 connectingstalkbetweenpouchandoralcavitydegeneratesWeek8 basophilicstainingcellsappearWeek9 acidophilicstainingcellsappearWeek10 growthhormoneandACTHdetectableWeek16 adenohypophysis fullydifferentiatedandTSHincreasestopeakat22weeksWeek20to24 growthhormonelevelspeak,thendeclineBirth secondTSHsurgeanddecreasespostnatal

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    Thevascularsystemofthepituitary

    Thepituitaryglandmaintainsconnectionswiththebrainbutsitsoutsideofthebloodbrainbarrier.

    Thepituitaryhasoneoftherichestbloodsuppliesofanywhereinthebody.

    Theposteriorlobeissuppliedbytheinferiorhypophyseal artery

    Theanteriorlobeissuppliedbythesuperiorhypophyseal artery

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    Thevascularsystemofthepituitary

    Thelongportalvesselsofthesuperiorhypophyseal arteryformsthebasisofthehypothalamohypophyseal portalsystem.

    Inhibitoryorstimulatingpeptidesarereleasedfromthemedianeminenceandquicklytransportedtotheanteriorpituitary.

    Oxytocinandvasopressinaresecretedbythemagnocellularneurosecretory cellsthathaveaxonalprojectionsintotheposteriorpituitary

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    Inductionofpituitarydevelopmentinthemouse

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    Differentiationofthesixmatureendocrinecelltypesoftheanteriorpituitaryisdeterminedbytheactionofacascadeoftranscriptionfactors

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    Thyroiddevelopment

    Functionsfromweek10,requiredforneuraldevelopment,stimulatesmetabolism(protein,carbohydrate,lipid),reduced/absence=cretinism

    Hormones (aminoacidderivatives)Thyroxine (T4),Triiodothyronine (T3)

    Beginsat24daysasendodermalthickeningwhichoutpouches toformthethyroidprimordium.Asthetongueandthyroidgrowsthethyroiddescendsintotheneckventraltothehyoidboneandlaryngealcartilages.Theductthatisleftbehind thethyroglossal ducteventuallydisappears

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    Stage13 week45

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    Sagittalviewofthyroiddevelopmentinthecontextofthedevelopingtongue

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    thyroidmedianendodermalthickeninginthefloorofpharynxbetweenthetuberculum impar andthecopula

    Thisoutpouches toformthethyroiddiverticulum tonguegrows,cellsdescendinneck thyroglossal duct proximalendattheforamencecumoftonguethyroglossal duct thyroiddiverticulum hollowthensolid,rightandleftlobes,centralisthmus

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    Parathyroidfunction

    4glandsintheneckontheposteriorsurfaceofthethyroidaboutthesizeofagrainofrice

    ParathyroidHormone Increasecalciumions[Ca2+]inthebloodstimulatesosteoclasts,increaseCa GITabsorption(oppositeeffecttocalcitoninproducedbytheparafollicular cellsofthethyroidformedfromtheultimobranchial body)

    AdultCalciumandPhosphate Dailyturnoverinhumanwithdietaryintakeof1000mg/day

    secretedbychiefcells Principalcellscordsofcells

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    Parathyroiddevelopment

    Derivedfromthe3rd formstheinferiorand4th pharyngealpouches formsthesuperiorPositionswapsroundduringdevelopmentElongatesasadiverticulumandthensolidifiesinitsfinallocationEpitheliumofthe3rd and4th pouchproliferatesduring5th weektoformsmallnodules,whichisinvadedbyvascularmesenchymetoformbloodvessels

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    ThymusfunctionThymus bonemarrowlymphocyteprecursorsbecomethymocytes,andsubsequentlymatureintoTlymphocytes(Tcells)Thymushormones thymosins stimulatethedevelopmentanddifferentiationofTlymphocytes.Notlimitedtothethymus.

    ThymusDevelopmentEndoderm thirdpharyngealpouchWeek6 diverticulumelongates,hollowthensolid,ventralcellproliferationThymicprimordia surroundedbyneuralcrestmesenchyme,epithelia/mesenchymeinteraction

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    Schoenwolf: Larsen's Human Embryology, 4th ed.Copyright 2008

    Pancreasdevelopment

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    Pancreas

    99%exocrinefunction secretionofpancreaticjuicethatincludestrypsin,chymotrypsin,elastase,carboxypeptidase,pancreaticlipase,nucleasesandamylase

    Isletsoflangerhans Alphacells glucagon(increaseglucose) Betacells insulin(decreaseglucose) Deltacells somatostatin (regulatesalphaandbetacells) Gamma(PP)cells pancreaticpolypeptide(selfregulatespancreatic

    functrion)

    PancreasTimeline Week7to20 pancreatichormonessecretionincreases,small

    amountmaternalinsulin Week10 glucagon(alpha)differentiatefirst,somatostatin (delta),

    insulin(beta)cellsdifferentiate,insulinsecretionbegins Week15 glucagondetectableinfetal plasma

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    Isletcells(yellow)formduringthebranchingmorphogenesisprocessfromendodermcells.Notethatthepancreasdoesntformbranchesthroughfolding(e.g.lung).Itformsastratifiedepitheliumwhichthencreatesmicrolumens thatcoalesce.

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    Adrenalglandsdevelopadjacenttothegonadsintheurogenitalridge

    Cortex mesenchyme,medullaneuralcrest6th weekcortexbeginsasaggregationofmesenchymeMedullafromsympatheticganglionderivedneuralcrestcellsLatermoremesenchymal cellsarisefromthemesotheliumandenclosethecortexCortexsecretesZona glomerulosa aldosterone(bloodpressure)Zona fasciculata glucocorticoidsZona reticularis androgensMedulla(chromaffin cells)secretes(modifiedsympatheticganglion)20%noradrenaline80%adrenaline

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    Suprarenal(adrenaldevelopment)

    Schematicdrawingsillustratingdevelopmentofthesuprarenalglands.A, At6weeks,showingthemesodermalprimordium ofthefetal cortex.B, At7weeks,showingtheadditionofneuralcrestcells.C, At8weeks,showingthefetalcortexandearlypermanentcortexbeginningtoencapsulatethemedulla.D andE, Laterstagesofencapsulationofthemedullabythecortex.F, Glandofaneonateshowingthefetal cortexandtwozonesofthepermanentcortex.G, At1year,thefetal cortexhasalmostdisappeared.H, At4years,showingtheadultpatternofcorticalzones.Notethatthefetal cortexhasdisappearedandthattheglandismuchsmallerthanitwasatbirth(F).Zona reticularis presentat3yearsold

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    Fetal cortexverylarge secretessteroidprecursorsusedbytheplacentaforthesynthesisofoestrogen.Theglandshrinksastheembryoniccortexregresses.

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    Gonadsasendocrineorgans

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    Placenta

    Humanchorionicgonadotropin(hCG) likeleutenizing hormone,supportscorpusluteum inovary,pregnantstateratherthanmenstrual,maternalurineinsomepregnancytesting

    Humanchorionicsomatommotropin (hCS) orhumanplacentallactogen stimulate(maternal)mammarydevelopment(possible) functionsimilartogrowthhormone

    Humanchorionicthyrotropin (hCT)orTSH Humanchorioniccorticotropin (hCACTH)orcorticotropinreleasinghormone progesteroneandoestrogens supportmaternalendometrium Relaxin

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    Other

    EndocrineHeartAtrialnatriureticpeptide(ANP) IncreaseFiltrationrate/decreaseNa+reabsorptionEndothelins ET1,ET2,ET3,Vasoconstriction/IncreaseNONitricoxide(NO) VasodilatationEndocrineKidneyRenin IncreaseAngiotensinaldosteronesystemProstaglandins decreaseNa+reabsorptionErythropoietin IncreaseErythrocyte(rbc)production1,25(OH)2vitaminD calciumhomeostasisPrekallikreins IncreaseKinin productionGITEndocrineEntericcontrolofdigestivefunctionGastrin Secretedfromstomach(Gcells),roleincontrolofgastricacidsecretionCholecystokinin smallintestinehormone,stimulatessecretionofpancreaticenzymesandbileSecretin smallintestinehormone(epithelialcells),stimulatessecretionofbicarbonaterichfluidsfrompancreasandliverAdiposeTissueLeptin polypeptidehormoneproducedinadiposeandmanyothertissueswithalsomanydifferentrolesAdiponectin regulationofenergyhomeostasisandglucoseandlipidmetabolism,aswellasactingasanantiinflammatoryonthecellularvascularwallResistin (forresistancetoinsulin,RETN)a108aminoacidpolypeptideandtherelatedresistinlikeproteinbeta(Resistinlikemoleculebeta,RELMbeta)stimulateendogenousglucoseproduction

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