Development of Renal System LECT 3 PDF

Development of urinary system Urinary and genital systems develop from the intermediate mesoderm Intermediate mesoderm is situated on the dorsal wall of embryo It projects into the intraembryonic celome Projection is called nephrogenic cord Series of kidneys develop from the nephrogenic cord Proneph...

Development of urinary system Urinary and genital systems develop from the intermediate mesoderm Intermediate mesoderm is situated on the dorsal wall of embryo It projects into the intraembryonic celome Projection is called nephrogenic cord Series of kidneys develop from the nephrogenic cord Pronephros: Initial kidney which develops from the nephrogenic cord in the cervical region Pronephros develops at the beginning of 4th week Pronephric tubules are excretory tubules formed in the pronephros Pronephric tubules open into the pronephric duct Pronephric duct runs caudally and opens into the cloaca Degenerates at the end of 4th week Urogenital ridge: This is the part of the nephrogenic cord (intermediate mesoderm) in the thoracic and upper lumbar region Urogenital ridge has 2 parts Genital ridge – medial part Mesonephric ridge – lateral part Mesonephric ridge (mesonephros): Second kidney It begins to develop at the end of 4th week Mesonephric tubules are formed in the mesonephos They open into the pronephric duct, which now called as mesonephric duct (wolffian duct) Mesonephric tubules degenerate Mesonephros gets degenerated at end of 2nd month Caudal tubules in the males remain and form duct system of testis (efferent ductules) along with mesonephric duct Metanephros: It is the permanent kidney It develops from the part of nephrogenic cord situated at the sacral region Metanephros forms the excretory part of kidney Collecting part (collecting tubules, minor and major calyces and renal pelvis) develops from the ureteric bud coming from the mesonephric duct Cloaca: It is caudal part of hind gut distal to allantoic diverticulum It is closed inferiorly by the cloacal membrane Urorectal septum divides the cloaca into two parts Urorectal septum joins the cloacal membrane and divides it into urogenital and anal membranes Parts of cloaca: 2 parts - Anorectal canal and primitive urogenital sinus Anorectal canal: It is the dorsal part of cloaca It develops into lower part of rectum and upper part of anal canal Primitive urogenital sinus: It is the ventral part of cloaca It is divided into 3 parts Vesicourethral canal Pelvic part of urogenital sinus Phallic part of urogenital sinus Vesiocurethral canal: It is the upper most part of primitive urogenital sinus Its cranial part forms the epithelium of urinary bladder Its caudal part in males forms the upper part of anterior wall of prostatic urethra, prostatic glands Its caudal part in females forms the upper part of anterior wall of urethra Pelvic part of urogenital sinus: In males it forms the lower part prostatic urethra and membranous part of urethra It forms the prostatic glands In females it forms the lower part of urethra and lower part of vagina Phallic part of urogential sinus: In females it forms the vestibule of vagina In males it forms the spongy urethra except the distal part (in the glans penis) Mesonephric duct: Initially known as pronephric duct After the degeneration of pronephros it is known as mesonephric duct Mesonephric duct receives mesonephric tubules Caudal end initially opens into cloaca, then into primitive urogenital sinus and finally into vesicourethral canal Ureteric bud originates from the caudal part of mesonephric duct Ureteric bud forms ureter, renal pelvis, major calyces minor calyces, collecting ducts Caudal part of mesonephric duct gets absorbed into vesicourethral canal Mesonephric duct and ureteric bud open separately into the vesicourethral canal Initially these openings are close together As the kidney ascends openings of ureteric buds move cranially At the same time openings of mesonephric ducts shifted caudally Fate of mesonephric duct in males: Caudal part of mesonephric duct gives a bud which develops into seminal vesicle Part of mesonephric duct caudal to the seminal vesicle develops into ejaculatory duct Part cranial to seminal vesicle develops into vas deferens and epididymis Structures derived from mesonephric duct in males: Epididymis, vas deferens Seminal vesicle, ejaculatory duct Ureter, renal pelvis, major calyces, minor calyces, collecting ducts Trigone of urinary bladder Upper part of posterior wall of prostatic urethra Appendix of epididymis Structures derived from the mesonephric duct in females: Most of the mesonephric duct in females degenerates and remains as a fibrous cord - duct of epoophoron (gartner’s duct) Mesonephric duct forms some of the parts of urinary system in females Ureter, renal pelvis, major calyces, minor calyces, collecting ducts Trigone of urinary bladder Upper part of posterior wall of female urethra Pronephros, Mesonephros and Metanephros Development of Kidney: Secretory part: From metanephric blastema Excretory part: From ureteric bud Development of Ureter: From ureteric bud Development of Urinary bladder: Epithelium of the bladder is derived from: Vesicourethral canal Epithelium of the trigone is derived from a absorbed mesonephric ducts. Development of Urethra: The part of the male urethra from bladder to opening of ejaculatory ducts, anterior wall is derived from vesicourethral canal and posterior wall from absorbed mesonephric ducts. The rest of the prostatic urethra and membranous urethra is developed from pelvic part of definitive urogenital sinus. The penile part of urethra from definitive urogenital sinus. The terminal part of urethra from ectoderm. Rotation Of the Kidney Anomalies of the Kidney A- Congenital polyscystic kidney, B-Aberrant renal arteries, C-Lobulated kidney, D,E,F-Transposition of kidney, G,H-Horseshoe kidney, I –Pancake kidney Anomalies of the bladder: A-Hourglass bladder, B- Ectopia vesicae