Fig. 1

Symptoms of hydrallantois in Japanese Black cattle. a, b Caudal views of an unaffected cow (a) and hydrallantois-affected cow (b) at 5 months (152 days) of pregnancy. Image shows abdominal enlargement in the affected cow (b) relative to the unaffected cow (a). c Abdominal circumference of the affected cows was significantly longer than that of unaffected cows at 5 months (152 days) of pregnancy (t-test, P = 0.0144). d Hydrallantois-affected fetus at approximately 160 days of gestation, estimated from crown-rump length (CRL). e, f Images of the sagittal section of the kidney in unaffected (e) and affected fetus (f) at approximately 160 days of gestation. Hydronephrosis was associated with dilation of the calices (white-arrows, f) in an affected fetus. g, h, i, j Micrographs of hematoxylin eosin-stained kidney sections from an unaffected fetus (g, i) and an affected fetus (h, j) at approximately 160 days of gestation. Atrophy of the renal cortex and medulla of kidneys in an affected fetus (h). Dilation of collecting ducts in the medulla of kidneys in an affected fetus (j). Scale bars: d = 10 cm; e, f = 1 cm; g, h = 1 mm; i, j = 100 μm