
pathogenesis of polycystic kidneys
microdissection confirms our previous de-
scription of an uncommon variety of poly-
cystic kidney found only in the newborn
periods.  it is characterized by symmetrical
enlargement caused by saccular or cylindri-
cal increase in size of all collecting tubules.
the number and relative length of different
generations of collecting tubules are normal.
nephrons are present in normal numbers,
and their attachment to collecting tubules is
normal.  the pattern of the nephrons is nor-
mal except for minimal localized areas of
dilatation.  interstitial connective tissue is
not increased.  intrahepatic bile ducts are in-
variably cystic.  siblings may be affected.
we believe that in such kidneys the be-
havior of the ampullae of the branches of the
ureteral bud is normal and that secondary
hyperplasia of the interstitial portions of the
branches is responsible for the greatly in-
creased renal size.
