DEVELOPMENT OF UROGENITAL SYSTEM
- Intermediate Mesoderm extends on each side of primitive dorsal aorta
- bulging on posterior abdominal wall lateral to dorsal mesentery
- आद्य मूत्रजनांग कटक ( urogenital ridge )
- Lateral Nephrogenic Cord
- extends from cervical to thoracic segments , each segment called nephrotome
- rest of unsegmented column , known as nephrogenic cord
- development and dissapearnace ( ONTOGENY REPEATS PHYLOGENY )
- firstly propnephros ( upper cervical and thoracic segments )
- pronephros dissapears except its duct
- from Solid cellular cord of cells
- acquires a lumen called as nephrocele
- evagination from dorsal wall
- grows laterally and then caudal backwards
- downturned ends join to form single primary excretory or pronephric duct
- bends in to urorectal septum
- opens in to ventral part of cloaca
- other end is present close to peritoneal funnel
- external glomerulus of capillaries project in to dorsal wall of coelom
- internal glomerulus
- metabolic wastes are liberated through these
- 7-8 segmentally arranged pronephric tubules
- Secondly mesonephros ( thoraco-lumbar direction )
- cephalic part of mesonephros dissapears
- caudal part shifts alleigance to genital system
- in males it forms the duct system of testes
- in females it forms part of broad ligament
- 70-80 Mesonephric tubules appear serially
- laterally opens in to pronephric duct
- mesonephric duct or wolffian duct
- medial end does not communicate with coelomic cavity
- internal glomerulus by a dilated blind end
- mesonephric tubules become S-shaped
- medial secretory part lined by columnar cells
- lateral collecting part lined by cuboidal cells
- each segment contains one mesonephric tubule and one glomerulus
- tracing caudally each contains 3 or more tubules
- each tubule is connected to numerous glomeruli
- proximal mesonephric tubules start disappearing around 5 th week
- ureteric bud develops from the mesonephric duct
- its distal end dilates and invades nephrogenic cord
- it shifts from dorsomedial to dorsolateral side
- cap like investment called metanephric blastema
- distal dilated end divides in to cranial and caudal parts
- future major calyxes
- the main duct connecting ureteric bud and mesonephric duct to cloaca is called
- common excretory duct
- around 8 th week 26 tubules and a single duct persist
- Thirdly metanephric blastema ( lumbo-sacral region )
- retained as the permanent kidney
- मध्य जननांग कटक ( Medial Genital Ridge )
- Cloaca
- आद्य मूत्रजनन गुहा (Primitive urogenital sinus)
- vesico-urethral canal
- urinary bladder
- primitive urethra
- निश्चित मूत्रजनांग गुहा ( Definitive urogenital sinus )
- pelvic part
- phallic part
Discussion