The most accepted theory is that the cases of HP located near the pancreas in the upper gastrointestinal tract are due to the incorrect placement of the dorsal and ventral pancreatic buds
during the embryological period, resulting in tissue separation during fusion (8).
The pancreas develops from the caudal part of the foregut, i.e., from the dorsal and ventral pancreatic buds originating from the duodenum (2, 3, 11, 19, 20, 31).
Pancreatic parenchyma is formed by the creation of a tubular network of the endoderm of pancreatic buds. In the early fetal period, acini develop from the cell clusters at the ends of these tubules (1, 3, 11, 19, 20).
While the dorsal and ventral pancreas buds are observed separately from the postcoital 30th to 33rd day in human beings, pancreatic buds as well as the duodenum to which they are connected show nuclear PDX1 and GATA4 positivity.
The most generally agreed-upon mechanism to explain the pathogenesis of HP was suggested by Hogan who proposed that it could be due to an early attachment of small pancreatic buds
to the intestinal wall at different sites, and when this connection continues, even after the pancreas separates from the gut, it results in HP .
Posterior and anterior foregut endoderm develops into ventral and dorsal pancreatic buds around E9 and E9.5, respectively.
Around the E9.5 stage, the pancreatic buds are formed from multi-potent progenitors that contribute to all cell types in the pancreas.
Ductal anomalies arise from variations in the fusion of the ventral and dorsal pancreatic buds
during embryological development and are usually clinically insignificant.
During embryogenesis these two pancreatic buds arise differently, the dorsal pancreas arises from just ventral to the notochord and caudal to the region of stomach, while the ventral pancreatic bud develops from the endodermal hepatic diverticulum.
The tetraspanin tm4sf3 is localized to the ventral pancreas and regulate fusion of the dorsal and ventral pancreatic buds. Development, 136: 1791-1800.
It was also observed that the developing islets were found in close relation to an intercalated duct in early postnatal stages that surely indicates the ductal origin of islets, perhaps out of proportion of exocrine tissue which suggests that from the pancreatic bud there is formation of ductal and acinar element in the first place and then these ductal epithelium differentiates into islet cells.
The pancreas is formed by the dorsal and ventral pancreatic buds
from foregut endoderm.