Light- and electron-microscopic analysis of the kidney in newborn rats exposed to gentamicin in utero.

Kidneys of newborn rats, whose mothers were given 75 mg/kg of gentamicin daily from the tenth day of gestation to its term, were examined by light and electron microscopy, as were kidneys of control rats whose mothers were given saline during the same period. In the gentamicin-treated group, the numbers of differentiated glomeruli and of S-shaped bodies counted in a median cross-section of the kidney were reduced, compared with those in the control group, but the glomerular volume was the same. In newborn rats issued from gentamicin-treated mothers, the proximal tubular lumen of the mature nephron lying in the deepest cortex was dilated, and their proximal tubular cells exhibited extensive damage, resembling that described in tubular cells of adult rats exposed to gentamicin. The subcapsular nephrogenic zone exhibited focal alterations of cytoplasmic organelle membranes, as well as nuclear lesions of several types, in cells of the nephron anlagen of the undifferentiated metanephric blastema, which were otherwise of normal appearance.