Development of GI Flashcards
(78 cards)
the 7th week, we see urorectal septum fusing with the clocal; then its divided into dorsal anal membranes and a larger ventral genital membrane
Fusion of the urorectal septum with the cloacal membrane becomes the perineum
Abnormalities of the Hindgut
Congenital Megacolon
1-neural crest cells do not migrate into the wall of the colon during the 5-7th weeks gestational age
2-results in a decrease in parasympathetic ganglion cells
3-decreases peristalsis in the aganglionic segement
4-we see an elargement in the proximal part of the colon
5-results in a lack of migration of neural crest cells into colon 5-7th week
1/5,000
**Most common cause of neonatal obstruction of the colon**
accounts for 33% of neonatal obstruction
- males more affected than females with a 4:1 ratio
- most cases, rectum and sigmoid colon are involved
- obstruction is primarily due to lack of peristalsis in that part of the colon without ganglion cells
In the liver as it develops: initially the right and left lobe are of equal size, but then the right lobe becomes larger as hematopoisis begins during the 6th week of embryological development
What disorder presents with complete or partial bowel obstruction?
Annular Pancreas
What week does failure of the anal membrane to rupture result in an imperforate anus?
8th
where is the duodenum developed from?
caudal part of the foregut and the cranial part of the midgut
Pancreas
with rotation , the pancreatic buds fuse;
happens as a result of rotation
Patent Urachus, urachal sinus or urachal diverticulum
Hindgut abnormalities
- Allantois runs along the umbilicus
- Allantois gives rise to the urachus
- Urachus is a canal that drains the bladder nd runs within the umbilical cord to the urinary bladder in the fetus
- as the fetus develops, the canal (or tube), becomes obliterated; HOWEVER, in this situationm the tube does not become obliterated sp we have a patent urachus, urachal sinus, urachal diverticulum or cyst
- incomplete obliteration of allantois may involve the umbilicus
Abnormalities if the Hindgut
VOLVULUS
- an obstruction resulting from faulty midgut rotation
- will result in/causes:
pain
bilious vomiting
GI bleeding
Failure to thrive
**This is a surgical emergency** so tht no further degeneration of the bowl will occur
HINDGUT ABNORMALITIES
Congenital Megacolon
Imperforate Anus
Patent Urachus (sinus, diverticulum, cyst)
Volvulus
developmental abnormlities of the stomach
PYLORIC STeNOSIS
- most common
- more common in males
1 in 150 males; 1 in 750 females
- results from a muscular thickening of the pylorus
- muscles become hypertrophied which causes the obstruction
SIGNS: Projectile Vomiting
onstruction of the passage of food
when does the exophagus reach its final length?
7th week
Development of the Esophagus
1-develops from the foregut
2-located behind the pharynx
3-division of the trachea from the esophagus occurs by the esophageal septum
4- Initially the esophagus is short, but it reaches it’s final length by the 7th week
5-musculature comes from connective tissue from the pharyngeal arches
6-1st solid tube that opens by the end of the embryonic period
7-covered with smooth muscle
8-invervated by branches of the vagus nerve which is supplied by the pharyngeal arches
Anomalies of the Midgut
Omphalocele
Gasorschesis
umbilical hernia
when does esophageal atresia occur?
8th week
How does the lesser curvature grow?
RIGHT & CRANIALLY
Can see along with Down’s Syndrome/intestinal malrotation and/or cardiac defects:
ANnular Pancreas
Causes of hepatic abnormalities
EXTRAHEPATIC BILIARY ATRESIA
- failure of the system itself to develop
- infection in pregnancy
- immunolog reaction late in fetal development
Development of the Spleen
- develops from the mesentary that’s attatched to the stomach
- the spleen is a vascular lymphatic organ
- rotation of stomach moves the spleen to the left side of the abdominal cavity
- spllen begins to develop as lobes in the fetus
- primitive connective tissue involved with these lobes; lobes disappear before birth
- it’s the connective tissue that provides tissue framework for the spleen to actually develop
- begins to develop during the 5th week but does not gain recognition until early in the fetal period
- spleen functions as a hematopoetic organ until later in fetal life
- Interesting that the spleen does retain its potential for developing RBC’s even into adult life
- good back-up organ in terms of RBC production
development of large and small intestine
at the 10th week, the intestines/intestinal loop retracts back into the abdominal cavity where it rotates an additional 180 degrees counterclockwise
can cause obstruction of duodenum
Annular Pancreas
GASTROSCHESIS
- results from the incomplete closure of the lateral folds of the abdomen during the 4th week
- abdominal contents protrude to the right of the umbilical cord -
- area is weakened by regression of the right umbilical vein
- intestines are not covered by a membrane
1/10,000 births
occurs more in males
typically not associated ith any other genetic/chromosomal anomalies
result of a weakened area where the right umbilical vein regresses
the pancreas starts out as 2 buds and with the rotation of the stomach, they (buds) come together and actually form the pancreas
pancreas
Omphalocele
(ventral wall defect)
presistence of herniated contents into the proximal part of the umbilical cord
- 1/5000 births
- abdominal cavity is small in these babies
- omphalocele is covered by a membrane or sac in the epithelium f the ubiical cord which comes from the amnion
- occurs because the the contents don’t go back into the abdominal cavity
- a=but also caused by impaired growth of muscle and skin of abdomoinal wall that contributes to it as well
