Duodenal Web and Bowel Duplication

The gastrointestinal tract starts as a hollow tube. Proliferation of the lining endothelium results in obliteration of the lumen. With time, vacuoles form within this cel-

Intraembryonic Coelom Development

Fig. 2—2. Cross-section at the end of the fourth week of embryonic development.

The envelopment of the intraembryonic coelom is almost complete. The yolk sac has otherwise separated into a more definitive yolk stalk and midgut as well.

(From Javors BR, Sloves JH.4)

lular plug; they coalesce and a normal diameter lumen is reestablished. Failure of complete resorption may lead to either atresia or stenosis. Stenosis may range from a conical narrowing to a weblike constriction (Fig. 2-7). An alternative hypothesis for atresia and stenosis of the intestinal tract is intrauterine ischemia.6'7 Very rarely, especially in the duodenum, ongoing peristalsis may propel intestinal contents against a web, stretching it out until it resembles a wind sock, forming an intraluminal diverticulum8 (Fig. 2-8). In addition, incomplete merging of the vacuoles may result in intestinal duplication.9-11 This is almost invariably seen along the mesenteric border, sharing the blood supply of the normal intestinal lumen. In the stomach, a duplication lies along the greater curvature (site of the initial dorsal mesentery, later the greater omentum)12,13 (Fig. 2-9), and in the colon along the medial wall of the ascending and descending colon and the superior wall of the transverse colon11,14 (Fig. 2-10).

Esophageal Duplication

The relative contributions of the septum transversum, esophageal mesentery, and pleuroperitoneal membranes will change with further development. (From Javors BR, Sloves JH.4)

The relative contributions of the septum transversum, esophageal mesentery, and pleuroperitoneal membranes will change with further development. (From Javors BR, Sloves JH.4)

Duodenal Web

Fig. 2-4. Foramen of Bochdalek hernia.

(a) Upper gastrointestinal series shows a normal subdiaphragmatic position of the stomach. The jejunum enters the thoracic cavity through a diaphragmatic opening (foramen of Bochdalek) that is situated on the left and is more lateral than the position of a conventional hiatal or foramen of Morgagni hernia.

(b) Lateral chest radiograph reveals the barium-filled colon reaching almost to the apex of the chest. The colon is seen to enter the chest through a diaphragmatic opening that is far posterior.

(From Javors BR.3)

Fig. 2-4. Foramen of Bochdalek hernia.

(a) Upper gastrointestinal series shows a normal subdiaphragmatic position of the stomach. The jejunum enters the thoracic cavity through a diaphragmatic opening (foramen of Bochdalek) that is situated on the left and is more lateral than the position of a conventional hiatal or foramen of Morgagni hernia.

(b) Lateral chest radiograph reveals the barium-filled colon reaching almost to the apex of the chest. The colon is seen to enter the chest through a diaphragmatic opening that is far posterior.

(From Javors BR.3)

Duodenal Web

Fig. 2—5. Cross-section through a five-week embryo at the level of the liver shows the paired superior peritoneum (right and left) separated by both the ventral and dorsal mesenteries. Even at this stage of development, the origins of many of the suspensory ligaments of the adult are clearly demonstrated. (From Javors BR, Sloves JH.4)

Duodenal Web

Left lateral film from an upper GI series shows an elongated, redundant postbulbar segment of duodenum proximal to the descending portion. This represents a persistent duodenal mesentery.

Left lateral film from an upper GI series shows an elongated, redundant postbulbar segment of duodenum proximal to the descending portion. This represents a persistent duodenal mesentery.

Annular Ligament

Left posterior oblique film from a double-contrast enteroclysis demonstrates a very thin annular constriction in the descending duodenum (curved arrows) from a duodenal web.

Left posterior oblique film from a double-contrast enteroclysis demonstrates a very thin annular constriction in the descending duodenum (curved arrows) from a duodenal web.

Diverticulum Intraluminal

Fig. 2—8. Intraluminal diverticulum.

Spot film from a single-contrast upper GI series reveals a saclike structure filled with debris and barium separated from the remainder of the duodenal lumen by a thin wall (arrows). Although termed an intraluminal diverticulum, this is actually a "ballooned out" duodenal web. (Courtesy of N. Spier, M.D.)

Gastric Duplication Cyst

Fig. 2—9. Gastric duplication cyst.

(a) Contrast-enhanced CT reveals a bilobate low-density mass (D) along the greater curvature of the stomach.

(b) Sagittal sonogram confirms the cystic nature of this gastric duplication cyst.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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