Embryo Final Clinical Correlates Fall '09

Front 1

Pectinate Line

Back 1

Has separation in muscles, blood/lymphatic supply and source of innervation (visceral vs. parietal). Dictate potential routes cancer infections may spread

Endodermal, proximal 2/3 of anal canal supplied by venous portal system. Lymphatic drainage is to the intestinal lymph trunks followed by the cisterna chyli. Innervated by visceral nerves
Ectodermal, distal 1/3 of anal canal is supplied by venous caval system. Lymphatic drainage is via superficial inguinal lymph nodes. Innervated by somatic nerves. Extremely sensitive to inflammation, irritation.

Front 2

Omphalocele

Back 2

Incomplete return of the midgut loop, forming a protrusion of intestines in the abdomen covered by peritoneum and amnion

Front 3

Leaves the herniated organs uncovered by any body wall of umbilical tissues, peritoneum, amnion (incomplete closure of the lateral folds and rectus abdominis)

Back 3

Gastroschisis

Front 4

When the buds of the pancreas fuse laterally around the duodenum on both sides (ventral and dorsal), leading to obstruction of the duodenum. Symptoms are vomitting during first few weeks of life. Can be fixed surgically.

Back 4

Anulate Pancreas

Similar to putting a noose around the duodenum (buds are supposed to grow on one side not both) and then tightening it. When digested food tries to pass through, there isn't enough space for the duodenum to expand to let it all through.

Front 5

Persisting of the Accessory Pancreatic Duct (of Santorini)

Back 5

A duct that leads from the dorsal bud of the pancreas directly from the body to the duodenum

Front 6

When the proximal part of the yolk stalk fails to undergo degeneration. This leads to a persistent connection between the yolk stalk and the midgut loop

Back 6

Meckel's (Ileal) Diverticulum

Since pluripotent germ cells use part of the yolk stalk as a pathway to the gonads, this connection could divert some into this area. The cells could then differentiate into gastric or pancreatic cells, secreting digestive enzymes and causing ulcers.

Fecal material may collect later in life
If a persistent opening remains, it is called an umbilical fistula and can allow wast products to pass out of the umbilicus of the newborn baby. Can be fixed surgically

Front 7

Improper rotation of the midgut cause abnormally twisted and constricted intestines and mesentery

Back 7

Volvulus

May be asymptomatic. Could also cause obstructed circulation, leading to necrosis and gangrene (e.g. superior mesenteric artery may be obstructed)
Could also cause strangulation of the bowels, not allowing digested matter to move easily from one section to the other
Abnormal fusion of the mesoderm to the body wall causes some of the small intestine to be enclosed in a small sac, an internal hernial sac which can strangulate the bowels.

Front 8

Due to failure of the migration of the neural crest cells to form the myenteric plexus in the sigmoid colon and rectum. Without these cells, there is irregulation of peristalsis movement in the bowels

Back 8

Hirschpsrung's Disease (Aganglionic/Toxic Megacolon)

Have an enlarged colon and rectum where fecal material is retained, causing a distended abdomen

Front 9

Autonomic imbalances and reduced migration of neural crest cells. Causes hypertrophic growth of pylorus (connection between stomach and small intestine) not allowing material to pass through. Symptoms include projectile vomiting in first few weeks

Back 9

Hypertrophic Pyloric Stenosis

Front 10

During development of the small intestines, there is enlargement and then temporary occlusion. Shortly after, there is apoptosis and rearrangement to open up the passageway again. Improper apoptosis can lead to atresia (still closed) or a stenosis (not fully opened). Can also develop a bifid (two smaller passageways contained within the bigger intestine) digestive tract

Back 10

Improper Canalization of the Bowels leading to Stenosis and Atresia (no opening)

Front 11

Failure of the urorectal septum to fuse with the cloacal membrane (which should open to create the end of the anal canal), leaving a persistent cloaca and a shared opening of the urethra and rectum Urorectal septum may fuse in a more dorsal location causing anal stenosis, anal agenesis (nondevelopment), anal-rectal agenesis or anala-rectal atresia
Possible fistula formation connecting the rectum to the perineum, the vagina or the urethra. All of these can be corrected surgically

Back 11

Abnormal Partitioning of the Cloaca