Fig. 2. Renal agenesis in Npnt-null mice. (A-C) Urogenital tracts from newborn female littermates, shown in wholemount. (A) Npnt^+/+ urogenital tract including kidneys with adrenals, ureters, bladder and uterine horns. (B) Npnt^-/- urogenital tract with unilateral kidney agenesis. Note that other than the absence of the right kidney and ureter (asterisk), the urogenital tract appears normal. The adrenal gland on the right is attached to the dorsal mesentery, and part of the dorsal aorta is present. (C) Npnt^-/- urogenital tract with bilateral kidney agenesis (asterisks). Again, the rest of the urogenital tract appears normal. (D,E) Medial sections of Npnt^+/+ and Npnt^-/- newborn kidneys (scale bar, 1 mm). Insets show regions containing glomeruli (arrows) at higher magnification (scale bar, 100 µm), demonstrating that kidney development, including nephron formation, occurs in Npnt^-/- kidneys. (F) Percentage of Npnt heterozygous and homozygous animals with two, one or no kidneys. The percentage agenesis was determined by dividing the number of kidneys [expected (2 per animal)-observed] by the number of kidneys expected. Ad, adrenal gland; Bl, bladder; DA, dorsal arota; Ki, kidney; Ur, ureter; Ut, uterus.