Annular pancreas in a fetus and its three-dimensional reconstruction.

A three-dimensional 50-times scale reconstruction was made of an annular pancreas from an 18-week-old fetus. By the use of radio-opaque paint, the anatomy of the pancreaticobiliary system within the reconstructed duodenum was clearly revealed. The anatomical arrangement indicated that the annulus was formed from the ventral anlage of the pancreas and that part of the annulus intermingled with the duodenal wall. These findings are consistent with Lecco 's theory of the embryogenesis of annular pancreas. The visualisation of internal structures in a reconstruction by the use of radio-opaque paint has not been described previously. This could be a useful technique in other embryological studies of the continuity of microscopic internal structures. Annular pancreas has been described previously by Weissberg in a 16-mm embryo. This report is the second case of a fetal annular pancreas in the literature.