L4 Development of the ureter, urinary bladder & urethra PDF

AL AZHAR UNIVERSITY Faculty of Medicine for Girls Year 2-Semester 3 Academic year: 2023 / 2024 Module Name: Renal module. Code: IPM-07-20318. Credit hours: 5 Anatomy & Embryology department Development of the ureter, urinary bladder & urethra By:...

AL AZHAR UNIVERSITY Faculty of Medicine for Girls Year 2-Semester 3 Academic year: 2023 / 2024 Module Name: Renal module. Code: IPM-07-20318. Credit hours: 5 Anatomy & Embryology department Development of the ureter, urinary bladder & urethra By: Dr. Shaimaa Hafez [email protected]  INTENDED LEARNING OUT COMES (ILOS ): B Y T H E E ND OF T H I S L E CT UR E, WE WI L L BE ABL E TO: 1 2 3 Describe the Understand the Describe development development of the development of urinary of urethra and ureter and its congenital bladder and its differentiate between its anomalies. congenital anomalies. congenital anomalies.  Development of the ureter The urogenital system develops from the intermediate mesoderm The metanephric diverticulum (ureteric bud):  It is an outgrowth from the mesonephric duct near its entrance into the cloaca.  It elongates dorsally then cranially.  Its stalk becomes the ureter.  Its expanded cranial end dilates to form funnel-shaped renal pelvis.  This pelvis splits into 2 portions then forms the major calyces.  Each calyx forms new buds these buds continue to subdivide until 12 or more times.  As the caudal ends of mesonephric ducts are absorbed into the wall of the bladder the 2 mesonephric ducts and the lowermost part of the 2 ureters come to open separately into the urinary bladder  Due to migration of the kidneys upwards the ureters increase in length and their orifices enter obliquely through the base of the bladder N.B. ureteric bud Ureter, major & minor calyces and collecting tubules DEVELOPMENT OF THE URINARY BLADDER  The cloaca:  The dilated caudal part of the hindgut (endodermal cells).  It is divided by the urorectal septum into dorsal rectum and a ventral urogenital sinus.  The urorectal septum develops at the angle between the allantois and hindgut and grows toward the cloacal membrane. The urogenital sinus is divided into 3 parts: 1. A cranial vesical (vesicourethral) part. 2. A middle pelvic part. 3. A caudal phallic part that grows toward the genital tubercle.  The urinary bladder:  Develops from 2 sources: 1. The vesical part of the urogenital sinus forms the main part of the urinary bladder. 2. The caudal ends of the mesonephric ducts forms the trigon of the bladder.  The epithelium of the bladder is derived from the endoderm of the vesical part of the urogenital sinus.  The smooth muscles develop from adjacent mesoderm.   The bladder is continuous with the allantois, when it becomes thick fibrous N.B. 1 cord it is called urachus.  the urachus extends from the apex of the bladder to the umbilicus.  In infants and children, the urinary bladder, is in the abdomen. N.B. 2  It enter the greater pelvis at 6 years of age.  It enters lesser pelvis at puberty. DEVELOPMENT OF THE URETHRA 1. Development of Female Urethra:  The entire female urethra is derived from endoderm of the urogenital sinus.  The connective tissue and smooth muscle are derived from splanchnic mesenchyme.  2. Development of Male Urethra: 1. The proximal part of the prostatic urethra 2. The distal part of the prostatic urethra (as far as, the opening of the ejaculatory +membranous part are derived from ducts) derived from lower part pelvic part of the urogenital sinus of vesicourethral canal. 3. The greater part of penile urethra derived 4. The part of penile urethra in the glans from the phallic part of the of the penis is derived from the urogenital sinus. surface ectoderm  2 Folds develop from the edges of the phallic part of the urogenital sinus on each side of the urogenital membrane;  Inner fold called urethral fold that unite from behind forwards to form the greater part of the urethra.  Outer fold called genital fold that unite form the scrotum. N.B.  The urogenital membrane:  Is the ventral part of the cloaca membrane.  It closes the phallic part of the urogenital sinus inferiorly.  CONGENITAL ANOMALIES OF THE URETER, URINARY BLADDER & URETHRA  I. Congenital anomalies of the ureter 1. Bifid renal pelvis and ureter: due to incomplete division of the metanephric diverticulum. 2. Retrocaval ureter: the ureter ascends posterior to the inferior vena cava. 3. Megalo-ureter: the ureter becomes wider more than 8mm. 4. Ureterocele: outpouching of the ureter as it enters bladder  II. Congenital anomalies of the urinary bladder A. Urachal Anomalies 1) Urachal cysts: Remnants of the epithelial lining of the urachus may give rise to cysts. 2) Urachal Sinus: A remnant of the lumen usually persists in the inferior part of the urachus. 3) Urachal Fistula: the entire urachus remains patent and form a urachal fistula that allows urine to escape from the umbilicus (Very rare). B. Recto-vesical fistula C. Ectopia vesica (extroversion of bladder): The posterior bladder wall protrudes through a defect in the anterior abdominal wall below the umbilicus. The trigone of the bladder and the ureteric orifices are exposed, and urine is dribbling  III. Congenital anomalies of the urethra 1) Hypospadias: the external 2) Epispadias: the external 3) Congenital recto- urethral orifice appears on urethral orifice is situated urethral fistula the ventral surface of the on the dorsal surface of the penis penis.  References: Allam, H.N. : Synopsis of Human Embryology. Devi, V.S. (2018):“Inderbir Singh’s Human Embryology”.11th ed. The Health Sciences Publisher, New Delhi, London Panama. Drake, R. A. Wayne Vogl, W. and Mitchell, A. (2017): Gray's Anatomy for Students. Elsevier. Kadasne, D.K. (2011):“Kadasne’s Textbook of Embryology”.1st ed. Jaypee Brothers Medical Publishers. Moore, K. L.; Persaud, T.V.N.; Torchia, M. G. (2013):“The Developing Human”. Clinically Oriented Embryology. 8th ed. Saunders Elsevier. Philadelphia. Moore, K. L.; Dalley, A. F. and Agur, A. M. R. (2010): Clinically Oriented Anatomy.6th Edition, Lippincott Williams & Wilkins, Philadelphia. Romanes, G. J.: Cunning hams Manual of Practical Anatomy.13th ed. London, Oxford University Press. New York, Bombay. Ronald W. Dudek, R. W. (2014):“BRS Embryology”. 6th ed. Lippincott Williams & Wilkins. Sadler, T. W. (2019): “Langman´s Medical Embryology”.9th ed. Lippincott Williams& Wilkins. Philadelphia, New York, London, Hong Kong, Sydney, Tokyo. pp. 298-301. Singh, V. (2017): “Textbook of Clinical Embryology”.2nd ed. Elsevier, Relx India Pvt. Ltd. Snell, R.S. (2008): “Clinical Anatomy by Regions”. 8th ed. Lippincott Williams& Wilkins. Philadelphia, New York, London, Hong Kong, Sydney, Tokyo. P. 253.