Glomerular size in renal dysplasia secondary to obstructive uropathy: a further exploration of the fetal lamb model.
OBJECTIVE
Creating an obstructive uropathy early in glomerulogenesis would produce multicystic dysplastic kidneys (MCDK). Measuring the mean planar area of the glomeruli (GMPA) may clarify the pathogenesis of MCDK.


METHODS
Fetal lambs at 60 days' gestation had their left ureter ligated and were delivered by cesarian section at 145 days' gestation. Kidney weight and length were recorded. GMPA in 3 zones (outer, middle, inner) of the sectioned kidney was measured using a computerized planimeter. The obstructed kidneys were compared with contralateral unobstructed kidneys. The unpaired Student's t test was used to determine significance.


RESULTS
One ewe miscarried. Four of 5 (80%) 60-day lambs survived. All had dysplastic kidneys. Mean kidney weights were 4.3 +/- 0.84 g in MCDK and 16.8 +/- 3.6 g in controls (P< .05). The GMPA of the outer, middle, and inner zones of the MCDK were 2.7 x 10(-3) mm2, 3.2 x 10(-3) mm2, and 4.0 x 10(-3) mm2, respectively. Controls were 2.8 x 10(-3) mm2, 4.4 x 10(-3) mm2, and 6.0 x 10(-3) mm2. The glomeruli of 60-day fetal kidneys were 3.0 x 10(-3) mm2, 6.1 x 10(-3) mm2, and 11.0 x 10(-3) mm2. MCDK had smaller glomeruli in the inner and middle zones than controls.


CONCLUSIONS
Fetal glomeruli appear to grow from the inner zone of the kidney. Early urinary tract obstruction stops this growth.
Kitagawa
H
H
Division of Pediatric Surgery aSt Marianna University School of Medicine, Kawasaki, Japan.
Pringle
K C
KC
Zuccollo
J
J
Koike
J
J
Nakada
K
K
Ikoma
M
M
Seki
Y
Y
D000818:Animals; D004195:Disease Models, Animal; D005314:Embryonic and Fetal Development; D005260:Female; D005333:Fetus; D007668:Kidney / Q000002:abnormalities / Q000196:embryology; D007678:Kidney Glomerulus / Q000196:embryology / Q000473:pathology*; D021782:Multicystic Dysplastic Kidney / Q000196:embryology* / Q000473:pathology*; D011247:Pregnancy; D011270:Pregnancy, Animal; D011336:Probability; D012016:Reference Values; D018570:Risk Assessment; D012756:Sheep; D014517:Ureteral Obstruction / Q000150:complications / Q000473:pathology*