Intrauterine growth restriction is associated with persistent juxtamedullary expression of renin in the fetal kidney

Background. Intrauterine growth restriction (IUGR) has been linked to impai red renal function and hypertension, suggesting that an adverse prenatal en vironment could alter kidney development and renin production. Methods. Immunohistochemistry and in situ hybridization were employed to lo calize renin-containing cells (RCCs) in the deep, middle, and superficial z ones of autopsy kidney sections, in parallel with histologic maturation, fr om unexplained stillborn fetuses of normal weight (N = 26) and stillborn fe tuses with IUGR (N = 17). Results. In the control group, the number of RCC per 100 glomeruli in the d eep zone decreased with advancing gestation from 40 at 20 weeks gestation t o five at term (P < 0.001), whereas the opposite change was found in the su perficial zone (increase from 5 per 100 to 55 per 100; P < 0.001). In the I UGR group, the density of RCCs in both the superficial and deep zones was s imilar to the control group at 20 weeks, and no shift in renin gene express ion was observed as gestation advanced. Histologic maturation was unaltered . Conclusions. Renin gene expression persists and predominates in the deep re nal cortex of the stillborn IUGR fetus, and could contribute to the pathoge nesis of neonatal oliguria and/or hypertension during postnatal life.