A QUANTITATIVE STUDY OF NORMAL NEPHROGENESIS IN THE HUMAN FETUS - ITSIMPLICATION IN THE NATURAL-HISTORY OF KIDNEY CHANGES DUE TO LOW OBSTRUCTIVE UROPATHIES

An evaluation of nephrogenesis according to fetal age was performed by quantifying the state of the nephrogenic blastema (NB) and the number of glomeruli (GN) on frontal renal sections in 99 control fetuses (ge stational age ranging from 9 to 40 weeks) and in 17 aborted fetuses wi th low urinary tract obstruction (gestational age ranging from 14 to 3 6 weeks). In the control group, GN increases slowly from the 10th to t he 18th week, then abruptly from the 18th to the 32nd week, reaching a n upper limit with NB disappearance by the 32nd week. In the uropathy group, the renal changes show a wide range of severity clearly account ed for by the impairment of both NB and GN. The dysplastic effect of u rinary backpressure is the more consistent pathogeny with the spectrum of observed renal changes. It is likely, from GN used as a time-depen dent marker of renal development, that the most severe dysplasia is th e result of early obstruction with abnormal disappearance of NB and su bsequent arrest of nephrogenesis.