Abstract
When one kidney is absent, the other undergoes the well-known compensatory hypertrophy. Most investigators agree that in cases of congenital defect the renal corpuscles (glomeruli) of the enlarged kidney appear to be increased in number (hyperplasia). In cases of postnatal, acquired renal defect, however, at least in adults, the renal corpuscles appear to be merely increased in size (hypertrophy) without increase in number. Even in young animals, the recent investigations of Arataki 1 (albino rat at 20 days) indicate no increase in the number of renal corpuscles after unilateral nephrectomy.
But these experiments were performed upon animals in which the normal formation of new renal corpuscles had almost or entirely ceased. Kittelson 2 has shown that in the rat the corpuscles have nearly reached the adult maximum number at three weeks of age. It seems possible that the removal of one kidney in the rat shortly after birth, when the new formation of corpuscles is still active, might produce a corpuscular hyperplasia, comparable to that found in cases of congenital absence of one kidney.
In order to test this possibility, the present study was undertaken. In a female albino rat one week old, body weight 9.09 gm., the right kidney was removed. It weighed 0.049 p. Two weeks /later the rat was killed at 21 days of age, body weight 24.4 grn. The left kidney weighed 0.214 grn., which is about 34 per cent above Donaldson's 3 norm for kidney weight (female) at corresponding body weight.
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