Three-dimensional reconstruction of the ventral and dorsal pancreas: a new insight into anatomy and embryonic development.

The recent introduction of limited resections of the ventral pancreas for benign disease and for low-grade malignancies calls for a thorough understanding of its anatomy. The two embryonic anlagen were characterized and distinguished through a comprehensive study of their macroscopic, histologic, and immunohistochemical characteristics in 20 autopsy specimens before reconstruction. Sections were histologically stained with hematoxylin-eosin and Grimelius and immunohistochemically stained with antibodies to insulin, glucagon, somatostatin, and pancreatic polypeptide by the avidin biotin complex method. The ventral and dorsal anlagen of the pancreas were reconstructed from eight autopsy specimens, using the "macroserial" method, after serial sectioning and immunohistochemical staining with anti-pancreatic polypeptide antibodies. Compared with the dorsal pancreas, the ventral pancreas was characterized by the presence of smaller and more closely packed lobuli, irregular rather than uniform islets of Langerhans, and rich immunostaining with anti-pancreatic polypeptide. Construction of the two anlagen showed that the dorsal pancreas consisted of the anterior part of the head of the pancreas, and the body and tail of the pancreas, while the ventral pancreas consisted of the posterior part of the head of the gland and the upper two-thirds (62.5%) or all (37.5%) of the uncinate process. The ventral pancreas was related to the right lateral surface of the superior mesenteric vein extending to the back. However, it did not extend across the front surface of the superior mesenteric vein to the left as previously described. The uncinate process was also located posterior to but not anterior to the superior mesenteric vein. The contributions of the ventral and dorsal anlagen to the anatomy of the pancreas gland as demonstrated in this study differ, in some relevant features, from the classical descriptions in the medical literature. The current anatomical findings add essential knowledge for the pancreatic surgeon who contemplates tissue-preserving resections.