Embryology Flashcards
What are the specific transcription factors expressed for early development of the:
Esophagus and Stomach
Duodenum
Small Intestine
Large Intestine and Rectum
Esophagus and Stomach: SOX2
Duodenum: PDX1
Small Intestine: CDXC
Large Intestine and Rectum: CDXA
What is the function of sonic hedgehog?
To initiate epithelial-mesenchymal interaction throughout the gut tube.
SHH expression upregulates factors in the mesoderm that then determine the type of structure that forms the gut tube. (i.e. SOX2, PDX1, CDXC, CDXA, HOX, etc)
What are clinical features of tracheoesophageal atresia?
Symptoms: Feedings produce coughing, choking, and cyanosis
Incidence of 1 in 3000 live births
Maternal polyhydramnios is often present b/c amniotic fluid is unable to pass through the intestinal tract due to atresia
What are the types of tracheoesophageal atresia and fistulas?
- Esophageal atresia (EA) with distal Tracheoesophageal fistula (TEF)
- EA without TEF
- TEF without EA: “H” type (often discovered later in life)
- EA with TEF to proximal esophageal segment
- EA with TEF to both proximal and distal segments
What are the anomalies associated with Tracheoesophageal Fistulas?
VACTERL Association:
Vertebral Defects
Anal atresia
Cardiovascular anomalies
TrachEoesophageal fistula
Renal Anomalies
Limb Defects
What kind of congenital malformations can occur in the GI tract?
- Duplication
- Hypertrophic Pyloric Stenosis
- Intestinal Atresia
- Meckel Diverticulum
- Hirschsprung Disease
- Omphalocele
- Imperforate Anus
What are clinical features of hypertophic pyloric stenosis?
- *Symptoms:
- Seen at 2-6 weeks as progressive, nonbilious* vomiting
- Visible peristaltic waves
- Almond-sized mass to right of midline**
- Male predominance (1 in 200 boys)
*Nonbilious b/c bile cannot get into the stomach from the Ampulla of Vater due to pyloric stenosis
What is the treatment of Hypertrophic Pyloric Stenosis?
- Longitudinal incision of hypertophied muscle down to mucosa
- Most common cause of abdominal operation in first 6 months of life
What are the clinical features of Intestinal Atresia?
Symptoms:
- Presents as obstruction:
Bilious vomiting
Abdominal Distention
- Maternal polyhydramnios: 25%
- Associated with Downs Syndrome and Cystic Fibrosis
- Equally in duodenum, jejunum, and ileum (infreq. in colon)
What are clinical features of Hirschsprung Disease?
- Congenital absence of intramural parasympathetic ganglion cells in distal GI tract
- *Symptoms:
- Abdominla distension
- vomiting
- Diarrhea
- Necrotizing entercolitis
- Perforation
- Chronic constipation (older patients)**
Ultra short segment disease may not present until later childhood or even adulthood (by chronic constipation)
What is Malrotation?
When the bowel returns to abdomen at end of 1st trimester, counterclockwise rotation of midgut occurs that puts colon anterior to duodenum and descending colon on left
In Malrotation, Nonrotation can occur that puts small bowel on right and colon on left
Reverse rotation puts colon posterior to duodenum
It is due to failure of fixture of mesentary to posterior wall of abdomen
What are clinical features of Malrotation?
Symptoms:
- Obstruction from volvulus
Vomiting
Abdominal Pain
Bleeding
- Associated with Downs Syndrome (trisomy 13 and 18)
- Resection of bowel may be required if infarcted
What is an omphalocele?
Abdominal wall defect in which abdominal organs protrude from the abdomen wrapped by amnion
What is gastroschisis?
Abdominal wall defect in which abdominal organs protrude from the abdomen not wrapped by amnion
What is Meckel Diverticulum?
- Remnant of vitelline duct that may connect to umbilicus
- Located on antimesenteric border, 1-3 feet from ileocecal valve
- Lined by intestinal or gastric mucosa
