Document Sample
Development-of-Urinary-System Powered By Docstoc
					                                                                                                                                 | Medicine
Development of Urinary System

Urogenital system                                                               Excretory system
Urinary system                                                                  Metanephric tissue cap – cover distal end of collecting tubule
Genital system                                                                  Under inductive influence, renal vesicles are formed
Common mesoder mal ridge                                                        (then form small S-shaped tub ules)
(eg. Intermediate mesoderm – along posterior wall of abdominal cavity)          Capillaries differentiate into glomeruli
Cloaca – excretory ducts (both systems) enter a common cavity                   Form nephros/ excretory units
                                                                                Form Bowman’s capsule
                                                                                Continuous lengthening of excretory tubules form
                                                                                Proximal Convulated Tubule (PCT)
                                                                                Loop of Henle
                                                                                Distal Convulated Tubule (DCT)
                                                                                At birth, kidneys are lobulated in appearance.
                                                                                Lobulation disappear during infancy (further growth of nephron )(but no ↑ in no. )

                                                                                Position of Kidney

Kidney systems
  Pronephros (1st )          Mesonephr os (2nd )        Metanephros (3rd )
  Rudimentary                Function for short time    Froms permanent
  Nonfun ctional             in early fetal period      kidney
  Represented by 7-10        Develop from               Excretory units
  solid cell groups in       intermediate               develop from
  cervical region            mesoderm                   metanephric             Kidney ascent (from pelvic region)(to cranial position in abdomen )
  (beginning of 4th week)    (upper thoracic → L3 )     mesoderm                Ascent is caused by growth of body in lumbar & sacral regions
  Cell groups form           1st excretory tubules      (metanephric            In pelvis, metaneprhos receive arterial supply from pelvic branch of aorta
  Vestigial excretory        appear (during             blastema)               During ascend (abdominal level), vascularised by arteries from aorta
  units, Nephrotomes         regression of                                      Lower vessels degenerate (some remain as accessory arteries)
  (regress before more       pronephric system)
  caudal ones formed )                                                          Functions of Kidney
  Disappeared                Lengthen to form           Collecting system       Functional within 12th week
  (by the end of 4th week)   S shaped loop              develop from ureteric   Urine passed into amniotic cavity mixes with amniotic fluid
                             Form Glomerulus            bud                     Fluid is swallowed by kidneys – recycled through kidneys
                             Form Bowman’s                                      During fetal life, kidney does not function to excrete waste products
                             capsule                                            (Placenta function to excrete waste products)
                             (Renal corpus cle)
                             Mesonephric duct
                             (Wolffian d uct)
                             Form Urogenital ridge
                             Caudal tubules (few)
                             and mesonephric d uct
                             persists (participate in
                             Male genital system

Collecting system
Develop from ureteric bud
Ureteric bud gives rise to
Renal pelvis
Major, Minor Calyces
1-3 million Collecting Tubules
                                                                                                                     | Medicine
Developmental anomalies of Kidney                                      Urinary Bladder & Urethra
Renal agenesis                                                         Cloaca divided by urore ctal septum into
Congenital polycystic kidney                                           Urogenital sinus
Horseshoe kidney                                                       Anorectal canal
Pelvic kidney                                                          3 portions of urogenital sinus
Complete & partial double ureter                                         Upper & Largest             Middle narrow canal     Last
                                                                         Form urinary bladder        Pelvic part             Phallic part
                                                                                                     Prostatic urethra
                                                                                                     Membranous urethra

Pelvic Kidney                           Horseshoe Kidney

Bifid Ureter                            Horseshoe Kidney

                                                                       Mesonephric ducts enter prostatic urethra to become ejaculatory ducts (Male)

Complete & Partial Double Ureter        Ectopic Ureteral Openings

Epithelium originates in Endoderm
Surrounding Connective Tissue & Muscle Tissue - Splanchni c Mesoderm
Epithelium of prostatic urethra
Form outgrowths (penetrate mesenchyme)
Buds for m Prostate Gland
Cranial part of urethra gives rise to Urethral & Paraurethral glands

Shared By: