kidney histology

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  2. 2. INTRODUCTIONBean shaped,reddish brown. Located retroperitonea/ /y between T12 L3 vertebral level. Size approx 10 x 6.5 x 3 cms.Weighs around 135-150 grams.Highly vascular organ. Receives 25 % of cardiac output. Kidney produces urine - ultrafiltrate of blood,which is then modified by selective resorption and specific secretion by cells of kidney.
  3. 3. FUNCTIONS OF KIDNEY 1. Regulates and maintains composition and volume of extracellular fluid. 2. Maintains acid base balance by excreting H+ ions orHCO3ons3. Endocrine organ a) Synthesis of acid protease RENIN - enzyme involved in control of blood pressure and blood volume. Angiotensinogen Angiotensinl Renin
  4. 4. b) Erythropoietin synthesis - glycoprotein hormone - regulates RBCs formation in response to decrease 02 concentration. - erythropoietin acts on specific receptors expressed on surface of CFU for erythrocytes in bone marrow.
  5. 5. c) Hydroxylation of 25OH vitamin D3 - a steroid precursor produced in liver. - converted to 1,25 (OH)2 vitamin D3, hormonally active.
  6. 6. ANATOMY OF KIDNEY
  7. 7. Capsule Connective tissue capsule. Outer layer fibroblasts and collagen fibres Inner layer myofibroblasts
  8. 8. _ _ .- _ _ .1 ' 1 - _ . - .I I - I 4 > A ' , . _ . _ 0 ., _ . . . , _-0 ' - o _ u_ .1 .- .. ' 2':'- 4' ._ . I so I .. .- _ .- .:- .'1 ,V _ - 4 T ' .. _ _ "' A .7 - outer lay en .~- ~. s - ~ .. x.- ' - J 4 'g i .I ~ - ' ' _ . - *- ' I T "' .T.4 , .. l 1 _ > - 4Q-,. - _ an ~ 'I "' .. -_. .- . _ I .-nerlayer- -v - .. ,. T ' ;~,' _ ' I . . .v ,. t- .l 0 c - - .5 q'> ~ " . -- - Q "a.' ,_ .- I , s. . ' .- ._-.V.- 5. ,_ . , . ~ -I| .I
  9. 9. F Myofibroblasts resist volume and pressure variation that accompany variation in kidney function.
  10. 10. Fcarts of kic! nev CortexMedullaRenal Pelvis
  11. 11. F 90-95 % of blood passing through kidney is in cortex,andF 5-10 % is in medulla.
  12. 12. Cortex Medulla - Pyramids (triangular areas of renal tissue)--. .Renal pelvis
  13. 13. Medullary pyramids have striped appearance due to presence of many collecting tubules. Tissue between pyramids is also a part of cortex and is known as RENAL COLUMNS.
  14. 14. - Tissue between base of pyramid and surface of kidney is known as CORTICAL LOULE. - Cortical lobules show light and dark striations,light lines are called lVIlEl3Ul. l./ -. R. RI-. .E. Contains straight tubules and collecting ducts. - Pyramid and the cortex around it constitute LOBE OF KlDiIl'-EY.Each kidney has 8-18 lobes.
  15. 15. RENAL LOBERenal Lobe
  16. 16. A thetip ofthcrenal pyramidApex of each pyramid extends downwards into renal pelvis and forms Renal Papilla
  17. 17. - Papilla is surrounded by funnel shaped Minor Calyx- Minor calyces join to form Major Calyx- Major Calyces join to form Renal Pelvis
  18. 18. .; x4.5% Pyramids___, j Hilus/UreterMajor calyxMinor calyx
  19. 19. - Kidney consists of collection of numerous Uriniferous tubules. Uriniferous tubule =Nephron + Collecting Duct. - Accompanied by capillary network called IASA RECTA,that runs parallel with tubules. - represent vascular part of countercurrent exchange system that regulates concentration of urine.
  20. 20. Afferent Efferent arteriolearterioleGlomerulusBowman's .C3P9U1 Proximal convoluted tubule Distal convoluted Descending llmb tub-la of loop of Henle Henle's loop Ascending limb of loop of Henle Collecting ductVasa recta
  21. 21. 1* Structural and functional unit of each kidney is Nephron. There are 1 million nephrons in each kidney.
  22. 22. URINIFEROUS TUBULEJNEPHRON + COLLECTING DUCTS1. NEPHRON- distributed throughout cortex and various zones of medullaa) RENAL CORPUSCLE BOWMANS CAPSULE + GLOMERU LUSb) PROXIMAL TUBULECONVOLUTED AND STRAIGHT PORTIONS C) HENLE'S LOOPTHICK AND THIN PORTIONSd) DISTAL TUBU LE STRAIGHT AND CONVOLUTED PORTIONS2. COLLECTING DUCTSDetailed structure of a nephronBowman's capsuleArterlole from renal arteryArterlole from glomorulusQ Loop of Henle with capillary network.Proximal tubule
  23. 23. Glomerulus + Bowman's capsuleGRenal CorpuscleBowman's Capsule Glomerulus
  24. 24. Renal Corpuscle has-1- Vascular Pole :Afferent arteriole enters and efferent arteriole leaves. 2- Urinary Pole :Proximal convoluted tubule begins. Marcello Malpighi - discovered renal corpuscles. Father of microscopic anatomy and histology.
  25. 25. Discovered by Sir William Bowman.Bowman's Capsule has 2 layers:1- Visceral Layer Inner- Contains podocytes. Podocytes extend processes around glomerular capillaries. 2- Parietal Layer - Contains parietal epithelial cells. simp| e squamous epithelium.
  26. 26. Afferent arteriole _> ._ Efferent ll! arteriole .4 -. _E
  27. 27. GLOMERULAR CAPILLARIESGlomerular endothelium has numerous fenestrations. Fenestrations larger more numerous more irregularEndothelial cells in glomerular capillaries has large number of aquaporin-1 water channels that allows fast movement of water through epithelium.
  28. 28. Glomerular Basement membrane Principal component of filtration barrier. Prominent in sections stained with PAS procedure.
  29. 29. RENAL TUBESRenal tubes are named according to A) Course they take Convolutedor Straight B) Location Proximal or Distal C) Wall thickness Thick orThin
  30. 30. leglomerulus afferent arteriole proximal convolutedtubule collecting/ duct 7Bowman's capsuleefferentarteriole _ distalconvoluted tubuleloop of Henle
  31. 31. Proximal convoluted tubule - originates from urinary pole of corpuscle.- tortuous.- located in cortex. Proximal straight tubule - - Known as THICK DESCENDING LOOP OF HENLE.- descends into medulla.- Discovered by Jacob Henle.
  32. 32. Thin descending limb - makes hairpin turn and returns towards cortex. Thin ascending limb Thick ascending limb - known as DISTAL STRAIGHT TUBULE.- ascends through medulla into cortex.
  33. 33. Distal Convoluted TubuleTv- Collecting TubuleTv -vCollecting Duct
  34. 34. CortexMedulla &(. Ureter / ll172 Proximal tubuleRenalcorpuscie -27" 7- -v 4 l l T 3 Loop oi -Hcnlc ' lIn some nephrons,the loop oi Homeis long and plunges into the medulla. A_/ '-4 Distal tubule/NYIn most nephrons. the loop or Home is relatively shortrand is located in the cortex. l rA- V 5_ Collecting ductFinal urine to ureterCortexMedulla
  35. 35. Cortex:- Glomerulus- Proximal and Distal convoluted tubules Medulla:- Loops of Henle - Collecting duct - Pyramids--. Renal pelvis:- Hilum - Major calyxes - Minor calyxes
  36. 36. efferent arteriole/ /afferent arterioleA aT 8owman's Capsule .= xa, mesangial cells podocytesBowman'sproximal tubuleglomerular capillaries
  37. 37. MESANGIAL CELLS Specialised cells in glomerulus. Also attached to capillaries. Mesangial cells with their extracellular matrix is called MESANGIUM.
  38. 38. Functions as macrophages in intraglomerular regions and phagocytose material that accumulates on glomerular filter. * Structural support for podocytes. ~ Secretes IL1 and platelet derived growth factor. ~ Regulates glomerular blood flow.
  39. 39. Some mesangial cells are located outside corpuscle along the vasular pole,and areknown as i. /ACES CEl. i.E. Flat cells with fine cytoplasmic processes. Form part ofluxtaglomerular apparatus. Controls glomerular blood flow.
  40. 40. Distal Loci:cells Tubule with Macula DenzsaAerent/ ,,~*. , . Arterlole ' , ' S Efierent * .4. Arterlole 5,:A.T-__,.- '' Parietal='~. _;_ Y. , __ 3 Layer or 5 i . * . ;._ I. I Renal'_T/' H i ' Corpuscle 4 V ' ' A .,. _ , Visceral Layer ~ .1 I 3wman-S of Renal Corpuscle .,.S (Podocytes) ' paceBeginning ol / Proximal Tbule
  41. 41. Proximal convoluted tubuleLonger and hence,are more numerous in cortex. Have small and uneven lumen. Contains single layer of cuboidal cells with eosinophilic granular cytoplasm. Cell boundaries are not distinct because of extensive basal and lateral cell membrane interdigitations with neighbouring cells.Cells have microvilli on their luminal surface ( typical brush border).
  42. 42. Distal convoluted tubuleShorter in length,therfore are few in number in cortex. Have larger lumen.Lined by small,cuboidal cells. Cytoplasm stains less intensely.Deep basal and lateral cell membrane infoldings and interdigitations are also present. Cells lack microvilli.
  43. 43. PCTsimple cuboidal epithelium PCTs have nuclei spaced some what DCTs have nuclei less spaced than farther apart than those ol DCTs those of PCTs moreinteneelylees intenselyeesinophillc thantheee comprising distal tubules comprising proximal tubules brush border of microvilli not have a brush border,although (apical ends less distinct than those of there may be scattered microvilli DCT).(apical ends more distinct than those of PCT).may be occluded lumen clearer lumenCells are extensively interdigitated -> boundaries between adjacent cells are inconspicuous (i. e..in section the epithelium looks like a continuous band of cytoplasm with nuclei appearing at irregular intervals). Because the proximal convoluted tubule is considerably longer than the distal convoluted tubule.a typical section of the renal cortex includes many more profiles of proximal tubules than of distal tubules
  44. 44. capsules~. rythrc~cytes_____. ..~"capillaries X 50 umI / proximal convoluted'ttll)ti| t3;3'distal convoluted tubule
  45. 45. Loop of He