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Fig. 7 | BMC Genomics

Fig. 7

From: A missense mutation in solute carrier family 12, member 1 (SLC12A1) causes hydrallantois in Japanese Black cattle

Fig. 7

Model of hydrallantois in Japanese Black cattle. a SLC12A1 is involved in the countercurrent mechanism in the kidney. In the kidneys of unaffected fetuses (left panel, a), SLC12A1 is localized at the apical membrane in the thick ascending limb of the loop of Henle and serves as a reabsorption molecule of Na+-K+-2Cl in the tubules. Transportation of Na+ from the intracellular to interstitial spaces by other transporters leads to an increased osmolality in the interstitial space. The increased interstitial osmolality draws water from the descending thin limb, progressively concentrating the primary urine in the tubules. In the affected fetus kidneys (right panel, a), SLC12A1 dislocates from the apical membrane to cytosol, in turn, impairing reabsorption of Na+-K+-2Cl in the thick limb of the loop of Henle, leading to defective concentration of urine via the countercurrent mechanism. Consequently, the affected fetuses exhibit polyuria. b Fetal urine storage in the allantoic cavity of the uterus. At mid-gestation, excessive volumes of allantoic fluid obstruct the outflow of fetal urine into the allantoic cavity (right panel b, dotted line) due to limited space in the uterus, resulting in hydronephrosis. The maternal abdomen becomes progressively distended and increases the pressure on the internal organs and fetus in the uterus, causing fetal death

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