renal hypoplasia

description

renal hypoplasia signifies small kidneys or kidneys with a reduction in the number of nephrons. it may be segmental, unilateral or bilateral. unilateral hypoplasia is associated with hypertension in the first decade of life. bilateral hypoplasia is associated with chronic renal failure and end stage disease during the first decade of life. polyuria and polydypsia are common symptoms. a rare bilateral form called oligomeganephronia is associated with a reduced number of markedly hypertrophied nephrons. at about 5 weeks after conception and throughout gestation until 32 to 36 weeks the ampulla or actively growing part of the ureteral bud undergoes multiple divisions and induces the development of nephrons and establishes communication with them. the metanephric blastema gives origin to the nephrons. differentiation, elongation and maturation of the components of the nephron (glomeruli, proximal and distal convoluted tubules and henle’s loop) continue even after birth. renal hypoplasia can result from any insult that interferes with this process. it has also been shown to result from acquired cortical loss in children with vesicoureteral reflux (vur). back pressure of urine exerted through later generations of nephrons (which are attached in direct alignment with collecting tubules unlike earlier nephrons attached at acute angles) can become distended into cysts and thus halt further nephron induction.