Development of the Digestive System – Core Vocabulary

This set of vocabulary flashcards covers the essential embryologic structures, developmental processes, and common congenital anomalies of the digestive system, providing a comprehensive review for exam preparation.

Foregut

Embryonic gut region supplied by the celiac artery that forms the esophagus, stomach, liver, biliary apparatus, pancreas, and upper half of the duodenum.

Midgut

Embryonic gut region supplied by the superior mesenteric artery that forms the lower duodenum, jejunum, ileum, cecum, appendix, ascending colon, and right two-thirds of the transverse colon.

Hindgut

Embryonic gut region supplied by the inferior mesenteric artery that forms the left one-third of the transverse colon, descending and sigmoid colon, rectum, and upper anal canal.

Dorsal Mesentery

Double-layered peritoneal fold that suspends the primitive gut tube from the posterior body wall .

What forms the greater omentum?

The dorsal mesentery

What gives rise to the stomach?

Dorsal mesogastrium

What gives rise to the duodenum?

Mesoduodenum

Ventral Mesentery

Peritoneal fold connecting foregut derivatives to the anterior body wall

What gives rise to the lesser omentum, the falciform ligament, and the coronary ligaments?

Ventral mesentery

Tracheoesophageal Septum

Partition that separates the foregut into a dorsal esophagus and ventral trachea.

Tracheoesophageal Fistula (TEF)

Abnormal communication between trachea and esophagus, most often associated with proximal esophageal atresia; presents with polyhydramnios and postnatal choking.

Esophageal Atresia

Blind ending of the upper esophagus, usually with a distal TEF; results from faulty foregut partitioning.

What gives rise to the 1st part of the esophagus?

Mesoderm of the caudal pharyngeal arches

What gives rise to the 3rd part of the esophagus?

Splanchnic mesoderm

Rotation of the Stomach

Ninety-degree clockwise turn that moves the left vagus nerve anteriorly, forms greater and lesser curvatures, and helps create the lesser sac.

What direction does the lesser curvature (ventral border) move to during development of the stomach?

The right

What direction does the greater curvature (dorsal border) move to during development?

The left

What happens after stomach rotation?

The left surface becomes the anterior surface, and the right surface becomes the posterior surface.

What is the nerve vagus nerve innervation after rotation?

Left vagus inmervates the anterior wall and the right vagus innervates the posterior wall.

How is the lesser sac formed?

Rotation of the stoamch, causing the dorsal mesentery to shift left, resulting in the formation of a space behind the stomach.

Lesser Sac (Omental Bursa)

Peritoneal recess posterior to the stomach produced by rotation and growth of the dorsal mesogastrium; communicates with greater sac via the epiploic foramen.

Greater Omentum

Large peritoneal fold formed from the elongated dorsal mesogastrium that hangs from the greater curvature of the stomach.

Dorsal mesogastrium

Divides into gastrophrenic, gastrosplenic, and lienorenal ligaments, supporting the stomach and spleen.

Congenital Hypertrophic Pyloric Stenosis

Postnatal hypertrophy of pyloric muscle causing non-bilious projectile vomiting, more common in male. linked to macrolide (erythromycin) exposure.

Duodenal Recanalization

Process during weeks 5–6 in which the temporarily occluded duodenal lumen reopens; failure causes duodenal stenosis or atresia (bilious vomiting, “double-bubble” sign).

Hepatic Diverticulum

Ventral foregut outgrowth that splits into pars hepatica (liver) and pars cystica (gallbladder and cystic duct).

What gives rise to the hepatocytes& intrahepatic ducts?

Endoderm from the foregut.

Kupffer Cells

Liver macrophages derived from mesoderm of the septum transversum.

When does hematopoiesis in the liver begin?

The 6th week.

When does bile first enter the duodenum?

After the 13th week of gestation.

When is bile first formed?

the 12th week of gestation.

Extrahepatic Biliary Atresia

Obliteration of bile ducts outside the liver, leading to neonatal jaundice and cholestasis; severe unless surgically corrected.

What gives rise to the gallbladder?

The caudal part of the pars cystica (ventral bud)

Gallbladder Floating

Variant where the gallbladder remains suspended by a mesentery because its bud lags behind hepatic growth; predisposes to torsion.

Intrahepatic gallbladder

When cystic diverticulum grows inside the hepatic bud.

Pancreatic Buds

Dorsal and ventral endodermal outgrowths that fuse to form the pancreas; ventral bud forms uncinate process and inferior head, dorsal bud forms rest.

Which pancreatic bud appears first?

The dorsal pancreatic bud.

What gives rise to the body, tail and upper part of the pancreas head?

Dorsal bud.

Main Pancreatic Duct (of Wirsung)

Duct created from the ventral duct, distal dorsal duct, and their anastomosis; empties at the major duodenal papilla.

Accessory Pancreatic Duct (of Santorini)

If present, the proximal dorsal duct that empties at the minor papilla.

Pancreas Divisum

Most common pancreatic anomaly caused by failure of duct fusion, leaving most pancreatic secretions to drain via the minor papilla.

Annular Pancreas

Ring of pancreatic tissue encircling the second part of the duodenum due to bifid ventral bud malrotation; causes duodenal obstruction.

When does the spleen develop?

The 5th week.

Physiological Umbilical Herniation

Temporary herniation of the midgut loop into the umbilical cord during weeks 6–10 because of rapid growth and limited abdominal space.

Midgut Rotation

Counter-clockwise (viewed anteriorly) 270° rotation around the superior mesenteric artery during herniation and return to the abdomen.

Non-rotation of Midgut

Failure of the final 180° rotation resulting in small intestine on right and colon on left; often asymptomatic but predisposes to volvulus.

Mixed rotation

There is no 3rd 90 degree rotation. Caecum is found under the pylorus here.

Midgut Volvulus

Twisting of inadequately fixed intestinal loops around the yolk stalk iif it persists as a cord fixed at the umbilicus.

Reversed rotation

Midgut rotation is clockwise. Duodenum is found in front of SMA.

Omphalocele

Persistence of midgut herniation into the umbilical cord, covered by amnion; frequently associated with other anomalies and trisomies.

Umbilical Hernia

Protrusion of intestine through a weak umbilical ring after return to abdomen; covered by skin and fascia, usually self-resolving. Trouble with the linea alba

Gastroschisis

Evisceration of abdominal contents through a right-sided para-umbilical wall defect without peritoneal covering; due to failed lateral fold closure.

Vitelline (Yolk) Duct

Connection between midgut and yolk sac that normally regresses; persistence leads to Meckel’s diverticulum or vitelline fistulas.

Meckel’s (Ileal) Diverticulum

Remnant of vitelline duct on antimesenteric ileum, ~2 in long, 2 ft from ileocecal valve; may contain ectopic gastric mucosa and bleed painlessly.

What mimics appendicitis?

Meckel's diverticulum due to its location in the ileum

Cloaca

Endodermal cavity receiving hindgut and allantois, partitioned by the urorectal septum into the anorectal canal and primitive urogenital sinus.

Urorectal Septum

Mesodermal wedge that separates cloaca; defective formation produces rectourethral or rectovaginal fistulas and anal agenesis.

When does the cloacal membrane rupture?

At the end of the 7th week

Pectinate Line

Junction in the anal canal between endodermal upper two-thirds and ectodermal lower third; marks changes in blood supply, innervation, and lymphatics.

What gives rise to the upper part of the anal canal?

The endoderm

What gives rise to the lower part of the anal canal?

The ectoderm

Blood supply of the lower third of the anal canal?

Inferior rectal artery from the internal pudendal artery.

Imperforate Anus

Failure of the anal membrane to rupture, blocking the anal opening; often associated with other cloacal septation defects.

Urorectal fistula

From abnormal development of the urorectal septum, leading to incomplete separation of cloaca.

Rectourethral Fistula

Communication between rectum and urethra due to abnormal cloacal partitioning; presents with meconium in urine.

Rectovaginal Fistula

Abnormal opening between rectum and vagina from faulty urorectal septum development.

Hirschsprung Disease (Congenital Megacolon)

Aganglionic distal colon from failed neural crest migration (RET gene mutation), causing functional obstruction and proximal dilation.

Greater Curvature

Left (dorsal) border of the stomach that grows faster during development, becoming the long convex border.

Epiploic Foramen (of Winslow)

Opening between the lesser and greater sacs located posterior to the free edge of the lesser omentum.

Falciform Ligament

Ventromesentery derivative attaching the liver to the anterior abdominal wall; its lower free edge contains the ligamentum teres hepatis.

Coronary Ligaments

Reflections of peritoneum from the liver to the diaphragm formed within ventral mesentery; delineate the bare area of the liver.

Lesser Omentum

Peritoneal fold from liver to stomach/duodenum composed of hepatogastric and hepatoduodenal ligaments; contains portal triad in its free edge.

Pars Hepatica

Cranial division of the hepatic diverticulum that forms liver parenchyma and intrahepatic bile ducts.

Pars Cystica

Caudal division of the hepatic diverticulum that forms the gallbladder and cystic duct.

Accessory Spleen

Small extra splenic tissue nodule (usually at hilum or in gastrosplenic ligament) arising from persistent lobules of splenic primordium.