Papillary Pore Counts: A Method of Studying Developmental Aberrations in Diseased Juvenile Kidneys

Counts of the number of pores of primary collecting tubules (ducts of Bellini) on renal papillae, and values calculated by adjusting the counts of compound papillae to those of “virtual” single papillae, were determined for kidneys of patients with end-stage renal failure. Values for chronic glomerulonephritis, Alport's disease, infantile polycystic disease, trisomy 18, and trisomy 13 were not abnormal. Kidneys of patients with CUTO showed significantly low pore counts, indicating that this process in some cases is a true hypoplasia, with mean reduction of number of ducts of Bellini of 26%. FGS showed a high proportion of single papillae (80% vs. normal 60%) with high virtual pore counts, suggesting that a developmental abnormality underlies this disorder (or this outcome of nephrotic syndrome). Cystinosis showed a high proportion of compound papillae (80% vs. 40%) but low virtual pore counts, implying that this genetic disorder causes both maldevelopment and postnatal functional abnormality of the kidneys. A Jeune syndrome kidney produced very low pore counts (mean 8 vs. 16.6 for virtual pore counts), and Down's syndrome also showed low pore counts (mean VPC 15.1 vs. normal 16.6), indicating that the low kidney weights demonstrated by others with Down's syndrome reflect a true hypoplasia.