ON THE ENLARGEMENT OF THE NORMAL CONGENITALLY SOLITARY KIDNEY

Objective To determine the anatomy of the normal congenitally solitary kidney and to complement an earlier investigation of the major functi onal parameters of congenitally and acquired normal solitary kidneys. Materials and methods A healthy congenitally solitary kidney was compa red anatomically with a normal control kidney from an equal pair in a man of similar height and age. Results The solitary kidney was about 1 .8 times heavier than the control; the diameter of its glomeruli and c onvoluted tubules were similar to those of the control kidney but ther e were twice as many glomeruli in the solitary kidney than in the cont rol. The total mass of glomeruli, as a percentage of the renal mass (a bout 5%), was the same for bath kidneys and essentially similar to tha t for mammals in general. However, the total mass of glomeruli as a pe rcentage of cortical mass was considerably greater in the congenitally solitary kidney than in the control, suggesting a relative deficit of convoluted tubular mass in the solitary kidney. Conclusion The normal congenitally solitary kidney is hyperplastic, i.e. there are more ele ments (nephrons), and apparently not hypertrophic. i.e. having larger nephrons.