Radiation injury in the neonatal canine kidney. II. Quantitative morphology.

Quantitative morphology was used to investigate injury induced in the developing canine kidney by ionizing radiation. Irradiation at 2 days of age destroyed nephrogenic tissue in the outer renal cortex and significantly reduced kidney weight and volume through 70 days of age. However, as early as 14 days of age and continuing through 200 days of age, hypertrophy was demonstrated in the surviving middle and inner cortical nephrons of these kidneys. Both corpuscular and tubular components of the nephrons grew at an accelerated rate as compared to controls. The corpuscular volume per nephron increased 559 per cent in irradiated dogs and only 249 per cent in controls from 14 to 200 days of age. The tubular volume per nephron increased 519 per cent in irradiated dogs and 303 per cent in controls during the same period. As a result of the compensatory growth in individual nephrons, the kidneys of irradiated dogs at 200 days of age were as large as the controls when compared on the basis of body weight. The extensive hypertrophy is associated with accelerated development of intercapillary glomerulosclerosis in dogs irradiated around the time of birth.