Back to Mesoderm…! Intermediate mesoderm Development After lateral folding… of under coelomic epithelium Urogenital Systems Lengthwise column Urinary system : ANHB 2212 – 2008 Nephric tubules Avinash Bharadwaj Open in the coelomic cavity, later… Draining duct The Kidney Story… Pronephros 8 to 10 “segments” – cervical Developmental and evolutionary Cell groups… Successive parts of intermediate mesoderm craniocaudal sequence Begins high up Disappear completely Three sets of “kidneys” Do not function as kidneys (only some species of fishes) First, middle and ‘other’ (final). Pronephros, mesonephros and metanephros Mesonephros Step-by-step … Thoracolumbar region Sectional view… Tubules Duct : mesonephric duct (Wolffian) Aorta Mesonephric duct Caudal end : Cloaca Æ urogenital part nd 2 month events Functional for a short period Paramesonephric duct 1 Mesonephros disappears Metanephros Tubules regress Caudal end of nephrogenic cord Duct persists… …put to some use! Duct : diverticulum from mesonephric duct Æ Ureteric bud Migrates cranially Metanephros Collecting System Pelvis Major calyces Minor calyces Major calyces Metanephric cap Pelvis Æ Urine-forming part Pelvis Major and minor calyces Ureteric bud Major calyces Collecting ducts Æ Collecting system Metanephric cap Æ tubules The Nephron The Nephron… Cell clusters around blind ends Glomerulus of tubules Parts of the tubule PCT Hollow DCT Thin part Æ Bowman’s capsule Proximal convoluted Rest Æ tubule Loop of Henle Loop Distal convoluted Communication essential ! 2 Ascent of Kidney Reproductive Organs Blood vessels : Gametogenic cells… successive sources Gonadal ridge Fused kidneys : Mesonephric and Arrested by IMA x paramesonephric ducts Gonads descend Common plan… M Differentiation P Male System Female System “Gubernaculum” M Paramesonephric duct Mesonephric duct Fusion : caudal part P Æ Uterus Cranial : Tube Uterine abnormalities. Female System Final Picture Uterine tube Descent stops in the Müllerian duct Ligament pelvis * of ovary* Gubernaculum Æ Fibrous cords Ovary Ligaments : Round Uterus : ligament Fused Müllerian Of ovary of uterus ducts Round ligament of uterus Vagina 3 Implications of Descent Blood supply Veins Nerves Lymphatics Inguinal canal and its contents 4.