Lab 18 –Urinary System Urinary System - Indiana University · Lab 18 –Urinary System Urinary...

UrinarySystemLab18– UrinarySystem

A560– Fall2015

I. IntroductionII. LearningObjectivesIII. SlidesandMicrographs

A.Kidney1. Generalstructure2. Cortexa. Corpuscleb. Proximalconvolutedtubulec. Distalconvolutedtubuled. Vasculature1. Afferentarteriole2. Efferentarteriole3. Peritubularcapillaries

3. Medullaa. LoopofHenleb. Collectingtubulec. Collectingductd. Renalpapillae. Vasculature1. Vasarecta

B. UreterC. UrinaryBladderD. Urethra

IV. SummaryFig19‐13,Junqueira,13th ed.

Learning Objectives

1. Understand the organization of the kidney into lobes and lobules and theirrelationship to cortical and medullary areas.

2. Understand the arterial input and venous drainage through the kidney’smicrovasculature.

3. Understand the structure of the renal corpuscle, including podocytes, and theultrastructure of the glomerular filter.

4. Understand the locations of the various parts of the nephron with respect tocortex and medulla.

5. Identify all parts of the nephron and collecting ducts in histological sections andunderstand how the structures of the different regions correspond to theirfunctions.

6. Recognize the structure and know the function of the juxtaglomerularapparatus.

7. Identify the key structural features of the ureter, bladder, and urethra.

Lab18– UrinarySystemA560– Fall2015





IV. Summary

Keywords

afferent arteriolearcuate arteriesarcuate veinsBowman’s spacecalyxcollecting ductcollecting tubulecortexdistal convoluted tubuleefferent arteriolefoot processesglomerular capsuleglomerulushilumjuxtaglomerular apparatusjuxtaglomerular cellskidneylacis cellsloop of Henle

macula densamedullamesangial cellsnephronperitubular capillarypodocytesproximal convoluted tubulerenal capsulerenal corpusclesrenal papillarenal pelvisthick ascending limbthin limbureterurethraurinary bladderurinary epitheliumvasa recta






IV. Summary






IV. Summary

Slide14:Kidney,Trichromelookhereforthecapsule

renalpelvis linedwithtransitionalepithelium(withsurroundingCT&adipose=renalhilum)






IV. Summary

Slide111:Kidney,H&E

renalpapilla

medulla

cortexhilum






IV. Summary

Slide111:Kidney,H&E

arcuatearteryandvein(bloodinlumen)atborderbetweencortexandmedulla

medulla

cortex

medulla

cortex

Blood flow through kidney:Renal artery segmental aa. interlobar aa. (between pyramids of medulla) arcuate aa. (betweenmedulla/cortex) interlobular aa. (in cortex) afferent arteriole glomerulus efferent arteriole peritubular capillaries / vasa recta interlobular vv.…






IV. Summary

Slide14:Kidney,Trichrome

renalcorpuscles

medullaryrays“extensions of medulla”into cortex; they consistof collecting tubules andducts draining nephronslocated higher in cortex;distinguished by absenceof renal corpusclesm

edulla

cortex






IV. Summary


glomeruli(capillarynetworks)withinBowman’scapsule ofcorpuscles

bulkofparenchymabetweencorpusclesisfilledwithtubules;cortexconsistsmainlyofPCTswithasmallernumberofDCTsandcollectingtubules






IV. Summary


Bowman’scapsule

(parietallayerofsimplesquamous

epithelium)

[vascular pole]

[urinary pole]

afferentarteriole(largerlumen)

efferentarteriole(smallerlumen)

PCT

maculadensa(specializedDCT)

(viscerallayerofpodocytes)

PCT

PCTglomerulus






IV. Summary

afferentarteriole

extraglomerularmesangial (Lacis)cellsformconicalmasscontinuouswithmesangium ofglomerulusandboundedbyafferentandefferentarterioleswithbaserestingonmaculadensa;cellsareflatandelongated;functionisunclear

maculadensaspecializedepithelialcellsofdistalconvolutedtubule;betweenarterioles;epithelialcellsaretallerandnucleiaresituatedmoreapicallythaninrestofDCT;cellsaresensitiveto[Na+]

Juxtaglomerular(JG)cellmodifiedsmoothmusclescellsofwallofafferentarteriole;clusteraroundarteriolebeforeitentersglomerulus(containsreningranules)

Juxtaglomerular Apparatus (JGA): specialization of afferent arteriole and distalconvoluted tubule (of same nephron); involved in regulation of systemic blood pressure






IV. Summary

capillaryendothelialcelldark,elongatednucleiaroundlumenofcapillaries

(intraglomerular)mesangialcellsdistinguishedasnucleiwithinmesangium(basementmembrane‐likematerial);pericyte‐like,secretematrix,andphagocytic

podocyteslarge,round,palenuclei;separatethenetworkofcapillariesintheglomerulusfromBowman'sspace;processessurroundthecapillariesandformfiltrationslits






IV. Summary


proximalconvolutedtubule(PCT)emergefromurinarypoleofcorpuscle;lumeniscontinuouswithBowman’sspaceandepitheliumiscontinuouswithepitheliumofparietallayerofBowman’scapsule

simplecuboidalepitheliumwithtallmicrovilli(brushborder);roundnucleiwithprominentnucleoli;intensely‐stainingcytoplasm;prominentbasallamina;lumenoftenappearsclosed;surroundedbyrichsupplyofcapillaries

PCTislongerthanDCT,somajorityoftubulesseenincortexarePCT

PCT






IV. Summary


distalconvolutedtubule(DCT)continuationofthickascendinglimbofloopofHenle;formmaculadensaatvascularpoleofcorpuscle

lackmicrovilli;generallyhavelarger,clearlydefinedlumen;morenucleipercrosssection(DCTcellsaresmallerthanPCTcells);palercytoplasmthanPCT

DCTismuchshorterthanPCT,sosectionsofDCTaremuchlessnumerousthanPCT






IV. Summary


afferent arteriolebringsbloodtoglomerulus;generallyhaslargerdiameterlumenthanefferentarteriole;itisoftendifficulttodistinguishbetweenafferentandefferentarterioles

efferentarteriolebringsbloodtoglomerulus;hassmallerdiameterlumenthanafferentarteriole,somaintainsfiltrationpressureinglomerulus;bloodwillcontinuefromefferentarterioletoperitubularcapillaries andvasarecta






IV. Summary


peritubularcapillaryfromefferentarteriolesofcorpuscleextensivenetworkaroundtubules,especiallyPCTsoreabsorbedglomerularfiltrate(~65%)isreturnedtovasculature






IV. Summary


medulla:NOrenalcorpuscles,lotsoftubes






IV. Summary


thick(ascending)limbfromthinlimbandconnectingtoDCTcuboidalepitheliumwhichlacksbrushborder;roundlumen;similarappearancetoDCT

thinlimbsimplesquamousepitheliumdifferentiatedfromvasarectabyregularroundshapeandlackofRBCsinlumen






IV. Summary


collectingtubule orconnectingsegment

connectDCTtocollectingduct

descendfromcortextomedullainmedullary

rays

similartothicklimbsbutarewiderandless

regularinshape






IV. Summary


collectingductformedfromseveralcollectingtubules;draintopapillaryductswhichopenattipsofrenalpapillaelargediameter;pale‐stainingcolumnarepithelium;prominentlateralbordersbetweenadjacentepithelialcellscanusuallybeseen






IV. Summary

Slide111:Kidney,H&E

renalpapilla






IV. Summary

Slide111:Kidney,H&E

papillaryductsductsofBellinifromcollectingducts

minorcalyx

transitionalepithelium

renalpapilla






IV. Summary


thicklimbs

thinlimbs

collectingducts

collectingtubule

vasarecta






IV. Summary

Slide48:Ureter,H&E






IV. Summary

Slide48:Ureter,H&E

transitionalepithelium(urinaryepithelium)






IV. Summary

Slide48:Ureter,H&E

lumenlinedbytransitionalepithelium






IV. Summary

Slide48:Ureter,H&E

Ureter is composed of mucosa, muscularis, and adventitia; the muscularis has two layers: innerlongitudinal and outer circular (a third outer longitudinal layer appears at the distal end as itjoins with the urinary bladder) – note the difference in the fiber orientations vs. in the GI tract






IV. Summary

Slide16:Aorta,VenaCava,Ureter,LN

ureter

noticetheverythick,prominentlaminapropria






IV. Summary

Slide12:UrinaryBladder,MassonTrichrome

mucosa forms prominent rugae in relaxed state






IV. Summary

Slide12:UrinaryBladder,MassonTrichrome

Paciniancorpuscle(inhumans?)

Three layers of muscularis collectively compose detrusor muscle: inner longitudinal, outercircular, and outermost longitudinal; however, the layers are often difficult to distinguish






IV. Summary

Slide109:Penis,H&E

urethra

urinaryepithelium(variable)






IV. Summary

Slide12:UrinaryBladder,MassonTrichromeSlide16:Aorta,VenaCava,Ureter,LN

TroublewithTubesUretervs.UrinaryBladder

basic organization of ureter (especially distal 1/3) and urinary bladder are the same; the key to differentiatingthem is to appreciate:1. Difference in size: notice the urinary epithelium lining the lumens, while comparable thickness in both

slides, it appears much thinner in the urinary bladder because the image is much more “zoomed out” asthe urinary bladder is a larger structure; in the ureter, individual nuclei can be seen in the epithelium,demonstrating a more “zoomed in” magnification level and an overall smaller structure

2. Mucosa of the urinary bladder often appears more much folded (rugae) when relaxed than in the ureter






IV. Summary

TroublewithTubesUretervs.Urethra

Slide109:Penis,H&ESlide16:Aorta,VenaCava,Ureter,LN

1. Ureter has adventitia and is often surrounded by adipose; urethra is embedded within the CT of thesurrounding organ, generally the penis or vagina

2. Urethra contains small mucous glands in the surrounding CT3. Ureter is lined by transitional epithelium; urethra is generally lined with pseudostratified columnar

epithelium (or transitional) that transitions to stratified squamous at the external urethral orifice4. Ureter has pronounced muscularis layer






IV. Summary

EMstoExamine

Fig19‐5:PodocyteFig19‐6:FiltrationbarrierFig19‐7:MesangiumFig19‐10:ProximalconvolutedtubuleFig19‐11:Thinlimbversusvasarecta

Segment Location Characteristics Function AssociatedVasculature

Proximalconvolutedtubule

Parsrecta(descendingthick)

Thinlimb(descending/ascending)

Ascending thicklimb

Distalconvoluted tubule

Collectingtubule

Collectingduct

Papillary duct

Lab18:CharacteristicsofSegmentsofUriniferous Tubule

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