Morphogenic development of the pancreas in the staged human embryo.

The Carnegie stage is widely applied in the field of human embryology, and it is more logical to analyze the embryos by this stage than CR length or menstrual age. In this study, the early development of the pancreas is studied by tissue observation and reconstruction using serial sections of 33 human embryo ranging from Carnegie stages 11 to 23. The dorsal pancreas develops from the dorsal wall of the duodenum in stage 12, and the ventral pancreas from the proximal part of the cystic primordium in stage 13 or 14 as a single epithelial thickening, but in one case, as a bilateral thickening which contains some isolated spaces. The rotation of the ventral pancreas starts in stage 15, and completes in stage 17. Surrounding connective tissue differentiates in stage 18.