Lecture 3 ESS_3rd semester MICROSCOPIC STRUCTURE OF THE URINARY SYSTEM / STAGES IN DEVELOPMENT OF KIDNEYS (pro-, meso-, and metanephros)/ MICROSCOPIC STRUCTURE OF THE URINARY SYSTEM - paired kidneys + ureters - unpaired bladder + urethra Function: - formation and elimeination of urine - regulation of fluid and electrolytic balance of the body´s internal millieu - production of some hormones - renin, erythropoietin - conveyance of gamets (the urethra in males) ulození_ledv abdom_ren Kidney - bean-shaped organ located on dorsal wall of the abdominal cavity (in retroperitoneal position) - size - 10-12 cm, 5-6 cm wide and 2-4 cm thick - hilum + convex aspect - topography superior pole - Th11 inferior pole - L3 v fibrous capsule v renal parenchyma v blood vessels kidney_diagr F19_01 Renal parenchyma: cortex and medulla Fibrous capsule – tunica fibrosa renis – dense collagenous tissue of irregular type pyramid renparenchyma_ Components of the renal parenchyma F19_01 •Renal corpuscle: in the cortex, •d. 150 mm, functions as filtration apparatus • •the glomerulus and Bowman´s capsule •2 poles – a vascular and a urinary • Bowman´s capsule • - visceral layer(podocytes) • - parietal layer Močový systém - 14 Ledvinný glomerul - schéma Nephron - its structure, histotopography, and function rencorpuscle_ 3b_Obr1c_agleff_upr 4_FOTO2 the glomerulus rencorpuscle The visceral layer of Bowman´s capsule F19_03 F19_05 Podocytes and fitration membrane F19_10 Podocytes and fitration membrane F19_07 F19_12 Renal corpuscles - distribution Bez názvu 3 kopie F19_09 Renal corpuscle – poles: vascular urinary Uriniferous tubule – tubulus renis F19_15 F19_14 F19_16 urinifer_tubul loopHenle Bez názvu 4 kopie Thin limb of loop of Henle F19_19 F19_22 Collecting tubules Bez názvu 1 kopie collecting_tub Medulla renis histotopo_nephron Histotopography of the nephron Juxtaglomerular apparatus juxtaglom_app F19_03 juxta kopie F19_21 Macula densa F19_24 Juxtaglomerular cells ren_cévy F19_25 Blood circulation of the kidney Blood circulation F19_25 cévnízasob F19_28 F19_27 Urinary passages cévnízasob Blood circulation of the kidney juxtaglom_app F19_02 F19_26 Introduction the urinary system and internal sexual organs develop from the intermediate mesoderm - a part of the third germ layer interposed between the axial mesoderm or somites and lateral mesoderm the intermediate mesoderm extends along the entire length of the dorsal body wall of the embryo it soon loses connection with somites and fuses to form the nephrogenic cords on each side of the primitive aorta the cords rapidly grow, become larger and produce bilateral longitudinal bulges called the urogenital ridges a medial side of each ridge is then separated from the surrounding and is called as the gonadal ridge (see the next chapter) Bez názvu 1upr Bez názvu 1upr Bez názvu 2upr DEVELOPMENT OF KIDNEYS, URETERS, BLADDER, AND URETHRA in the human, three sets of excretory organs develop: the pronephros (-oi) - "forkidney" - is rudimentary and nonfunctional; forkidney is analogous to the kidney of some primitive fishes, the mesonephros (-oi) -" midkidney" - is analogous to kidney of fishes and amphibians in human embryos, midkidney is probably functional for a short time and then undergoes involution the metanephros (-oi) - "hindkidney" or permanent kidney, it begins to produce urine in fetuses aged 11 to 13 weeks •Pronephros (oi) •occurs early in the fourth week in the cervical region on each side • •it consists of a few solid cell clusters, rarely short pronephric tubules and the pronephric •duct, which runs caudally and opens into the cloaca • •the pronephros soon degenerates, but most of both pronephric ducts are utilized by the •midkidney as mesonephric or Wolffian duct Močový systém - 31 •Mesonephros (oi) •develops later in the 4th week caudal to the pronephros in C6 to L3 region •initially, solid nephrogenic cord (blastema) divides into 40 - 50 mesodermal cell clusters within them lumina •develop - mesonephric vesicles arise •mesonephric vesicles grow into S-shaped mesonephric tubules whose laterally ends become •continuous with the mesonephric duct or Wolffian duct •the medial end of each tubule expands and transforms into •the Bowman´s capsule (capilary loops of the glomerulus are •deriving from the mesonephric artery) •the capsule with glomerulus form a mesonephric corpuscle •together • •cervical and thoracical parts of mesonephroi rapidly degenerate •the lumbar part consisting of a few mesonephric tubules and •mesonephric duct persists and is involved in development of •genital ducts in males (ductuli efferentes, ductus deferens and ductus •ejaculatorius) or vestigial remnants in females (epoophoron and paroophoron) Močový systém - 3 Vývoj mesonefros Močový systém - 33 •Metanephros (oi) •"hindkidney" or permanent kidney begins to develop early in the 5th week • •two different sources: vthe ureteric bud or metanephric diverticulum, which gives rise to the ureter, pelvis, major and minor calyces and system of papillary ducts and collecting tubules vthe metanephrogenic blastema or metanephric mesoderm = a caudal part of the • nephrogenic cord extending between L4 to S1 - it gives rise to the nephrons • Močový systém - 34 Močový systém - 35 Močový systém - 36 the ureteric bud begins as a dorsal outgrowth from the mesonephric duct near its entry into the cloaca the bud then extends dorsocranially, penetrates the metanephric mesoderm and divides it into cell clusters, located near blind ends of the collecting tubules clusters of mesodermal cells become metanephric vesicles that are later transformed into metanephric tubules the proximal part of each tubule becomes dilated and forms the Bowman´s capsule of a renal corpuscle, while the distal end contacts the respective collecting tubule and both tubules become soon confluent the remaining part of the metanephric tubule undergoes continual lengthening and gradually differentiates into definitive segments of the uriniferous tubule the proximal tubule, the loop of Henle, and the distal tubule Positional changes of the kidneys kidneys develop in the pelvis from the 2nd trimester, they gradually come to lie in the abdomen the migration of kidneys is mainly resulted from growth of the embryo´s body caudal to the kidneys Development of renal pelvis and ureter both derive from the distal part of the ureteric bud Development of bladder and urethra both organs develop from the ventral part of the cloaca the cloaca is the most caudal part of the gut which is ventrally sealed off by a membrane composed of the ectoderm and endoderm - known as the cloacal membrane cranially, the cloaca continues as the allantois that enters the connecting stalk in higher vertebrates inclusively the human, the cloaca soon divides with the urorectal septum (runs frontally) into 2 portions : - the anorectal canal situated dorsally - rectum, - the primitive urogenital sinus situated ventrally - bladder + urethra. the caudal part of the urorectal septum then fuses with the cloacal membrane: a part covering anorectal canal is the anal membrane, a part covering the primitive urogenital sinus is the urogenital membrane Močový systém - 37 the urogenital sinus includes three parts: Øvesical segment (presumptive bladder - there is a wide cranial part Øpelvic segment - middle narrow Øphallic segment - it appears wide the vesical segment develops into the definitive bladder - in both sexes the pelvic segment becomes the definitive urethra in females but the prostatic urethra in males the phallic segment of the urogenital sinus becomes the vestibule of the vagina in females but the penile urethra in males Močový systém - 38 CONGENITAL MALFORMATIONS OF KIDNEYS AND URETERS Renal agenesis = absence of a kidney it results from failure of the ureteric bud to growout and is accompanied with an absence of the ureter it may be uni- or bilateral (unilateral agenesis is characterised by compensatory hypertrophy of the kidney that is present; bilateral agenesis is incompatible with survival after birth) incidence is about 2 (3) per 10 000; is more frequent in males than females (3:1) clinically, it is always accompanied by oligohydramnios which results from failure of urine production Pelvic kidney = a kidney (s) is located in pelvis, this malformation results from failure of the kidney to ascend Horshoe kidney - both kidneys are fused at their inferior poles and located in pelvis (failure of kidneys ascend) horshoe kidney is often symptomless and occurs 1 per 600 live birth. Bez názvu 7aupr Polycystic kidney disease = hereditary disease characterised by that one or both kidneys contain numerous small, medium - sized or large urine-filled cysts inhibiting its normal function polycystic kidney disease may be uni- or bi-lateral bilateral p. k. d. has almost bad prognosis because it is incompatible with survival after birth P. k. d. is believed to result from failure of collecting tubules and uriniferous tubules to join up. Polycystic kidney disease includes two hereditary forms. One is autosomal recessive or infantile, the other is autosomal dominant, or adult. Duplication of the ureter - ureter duplex and bifid ureter (ureter fissus) Bez názvu 7aupr