Figure 1.

Diversity in the presence/absence of a gallbladder in rodents, and the definition of the mammalian hepatobiliary primordia. (A) Gallbladder evolution in rodents. The phylogenetic framework is based on Fabre et al. (2012), and the topology of the tree was arranged in Mesquite (Maddison & Maddison, 2011). The presence of a gallbladder is from Gorham & Ivy (1938) and Nzalak et al. (2010). The red dots indicate species that do not have gallbladders. The silhouette images are from PhyloPic (http://phylopic.org/). For more details, see Fig. S1. (B) Scheme of the left lateral view of the sagittal section of a pig embryo at the pharyngula stage. The hepatobiliary primordia arises from the foregut at the level of the septum transversum, caudal to the heart. (C) The hepatobiliary primordia in a pig embryo. The meshed domain is identified as the ‘hepatic diverticulum’ (sensu Patten, 1927). The diverticulum differentiates into the primordial liver, and biliary and ventral pancreatic buds. Of these, the biliary bud provides most of the extrahepatic biliary tract. The figures in (B) and (C) are redrawn from Patten (1927). bil, biliary bud; dpb, dorsal pancreatic bud; gc, glandular cord; hepdiv, hepatic diverticulum; lung, lung bud; st, stomach; vpb, ventral pancreatic bud. [Correction added on 24 October 2017, after first online publication: the abbreviations cited on this figure was added on figure caption]