Donor: Royal Victoria Hospital
Size (H x W x D cm): 14 x 9 x 3
A loop of partially opened ileum gives rise to a 3 x 1 cm diverticulum at its base (A, arrows).
A. Click on image to enlarge.
History: Three and 1/2 year-old boy who died of diphtheria; incidental finding at autopsy.
Comment: The early embryonic midgut is located between the presumptive pharynx and hindgut, and communicates broadly via the viteline duct with the yolk sac. Following a period of elongation, it forms the primary intestinal loop, whose apex is in continuity with the duct. The cephalic limb of the loop develops into the distal part of the duodenum, the jejunum, and most of the ileum; the caudal part forms the remainder of the ileum, the cecum and the ascending and proximal part of the transverse colon. The viteline duct normally disappears at approximately 6 weeks. However, a portion of it may persist as a diverticulum (Meckel diverticulum) or as a viteline cyst or fistula with the umbilicus.
Meckel diverticulum is one of the most common congenital anomalies, occurring in about 2% of the population. It can be up to 6 cm in length and as wide as the adjacent ileum. It is almost always discovered incidentally (e.g., at surgery for an unrelated condition or at autopsy). However, secretion of enzymes by gastric epithelial or pancreatic tissue in its wall may be lead to ulceration with pain, rectal bleeding, and/or perforation with peritonitis/sepsis. Additional rare complications include volvulus or intussusception.
Johann Meckel (1781 - 1833) was a German anatomist who studied both normal and abnormal human and animal development and wrote one of the earliest books to be published on the subject.