COMPARATIVE MORPHOLOGY OF THE GALLBLADDER AND BILIARY-TRACT IN VERTEBRATES - VARIATION IN STRUCTURE, HOMOLOGY IN FUNCTION AND GALLSTONES

A review of investigations on the morphology of the gallbladder and bi liary tract in fish, reptiles, amphibians, birds, and mammals was perf ormed. Scanning electron microscopy, transmission electron microscopy, and light microscopy observations by the authors were also included. Variations in the presence or absence of a gallbladder, surface epithe lium of the gallbladder, and differences in the morphology of the bili ary tract in vertebrates were reported. Many differences were diet-rel ated. Despite some dissimilarities observed, analogous functioning of the biliary system was accomplished by its various components, with th e biliary ducts performing the function of the gallbladder when this o rgan was absent. In addition, the occurrence of peculiar parasitism an d gallstones among some cases of vertebrates, including humans, was pr esented. (C) 1997 Wiley-Liss, Inc.