Anatomical study of the renal portal system in the duck (Anas platyrhincos).

Sixteen healthy mature ducks of both sexes were used in the present study. The injection of a polymerizing material was made via the posterior vena cava and, after a complete corrosion, casts were obtained for the examination of the entire venal network of the kidneys. Similar injections were made in a limited number of fowls, in order to facilitate the comparison between our findings in the duck and those in the fowl. The renal portal system as well as the renal veins of the duck were identified and illustrated in detail. The anatomical relation of the renal portal system to the renal veins and to the coccygomesenteric vein was examined and evaluated. From the comparison of the findings in the duck and fowl, the main differences in the duck were found to be the following: the cranial portal vein was rudimentary, the distance between the two caudal portal veins as well as that between the two renal veins was short, the posterior part of the caudal renal portal vein and the renal vein were located superficially and ventrally to the caudal lobe of the kidney, and the distance between the caudal renal portal vein and the homolateral vein was also short.