Meckel&;s diveiculum is a remnant of
**Core Concept**
Meckel's diverticulum is a congenital anomaly of the small intestine, resulting from the incomplete closure of the vitelline duct during embryonic development. This condition is characterized by the presence of a small, finger-like pouch on the antimesenteric border of the ileum.
**Why the Correct Answer is Right**
The vitelline duct is a structure that connects the yolk sac to the embryonic midgut during fetal development. Normally, this duct disappears as the embryo grows, but in some cases, it remains patent, leading to the formation of a Meckel's diverticulum. The remnant usually contains gastric or pancreatic mucosa, which can cause symptoms due to the secretion of acidic or enzymatic substances into the adjacent ileal lumen.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Meckel's diverticulum is not a remnant of the omphalomesenteric duct, which is another embryonic structure that connects the midgut to the umbilicus. The omphalomesenteric duct typically obliterates and forms the urachus or the median umbilical ligament.
**Option B:** This option is incorrect because Meckel's diverticulum is not a remnant of the appendix, which is a separate structure that arises from the caecum. The appendix develops from a portion of the midgut that is separate from the vitelline duct.
**Option C:** This option is incorrect because Meckel's diverticulum is not a remnant of the small intestine itself, but rather a congenital anomaly that arises from the incomplete closure of the vitelline duct.
**Clinical Pearl / High-Yield Fact**
Meckel's diverticulum can be a source of gastrointestinal bleeding, especially in children, due to the erosion of the adjacent ileal mucosa by gastric or pancreatic secretions. It can also cause intestinal obstruction or diverticulitis in some cases.
**Correct Answer: D. Vitelline duct**