
cellular proliferation and deoxyribonucleic acid
synthesis in compensating kidneys of mice
and the effect of food and water
restriction
compensatory enlargement of the kid-
ney occurred after unilateral nephrectomy
in mice.  fourteen days after the removal of
one kidney the surviving renal tissue                                  6
weighed 23 per cent more than single kid-
neys from sham-operated animals.  the
hyperplastic response of the cortex on the
second postoperative day was 8 times
greater than that seen in the same zone of
kidneys from sham-operated animals.  by
10 days after surgery the mitotic index of
the cortex returned to control values.  the
outer medulla also underwent hyperplasia
but only on the second day following
unilateral nephrectomy was the increase
significant.  an increase in mitotic activity
was found in the inner medulla of surviving
kidneys, but it was not statistically signifi-
cant.
both starvation for 48 hours and water
restriction for 60 hours prevented the hyper-
plastic responses in the remaining kidneys
2 days after unilateral nephrectomy.  when
water was given 48 hours after unilateral
nephrectomy (after 60 hours of water
restriction) significant increases in mitotic
activity were noted in the cortex of remain-
ing kidneys on the fourth and fifth post-
operative days.  however, even after free
access to food was allowed (after 48 hours
without food) no significant increase in
mitotic frequency of the remaining kidney
was found.
deoxyribonucleic acid synthesis in con-
trol kidneys of mice was highest in the cor-
tex and lowest in the inner medulla as
revealed by radioautographic studies fol-
lowing the injection of tritiated thymidine.
two days following removal of one kidney
the labeling index of the cortex of remaining
kidneys increased 3-fold.  no statistically
significant increases of deoxyribonucleic
acid synthesis were noted in either the outer
or inner medullary regions of the remaining
kidneys.
