The Effect of Unilateral Blockage of a Pronephric Duct upon the Development of the Pronephroi in Triturus helveticus

When one member of a pair of pronephroi is removed at an early larval stage in Ambystoma (Siredon) and Triton cristatus, the remaining one becomes larger than normal during subsequent development (Howland, 1916, 1921; Fox, 1956). The question may be posed as to whether pronephroi exercise mutual inhibitory effects upon one another, so that the removal of one of the pair allows the remaining organ to increase in size. In Rana nigromaculata and Bufo vulgaris japonicus partial or total reduction of one pronephric duct leads to hypertrophy of the contra-lateral pronephros and duct (Miura, 1930). No numerical data were supplied in this investigation. Obstruction to a Wolffian duct in the embryo chick leads to hydronephrosis on the same side and the other mesonephros becomes approximately twice the normal size (Boyden, 1927).