Embryology of the GI Flashcards
Define Gastrulation
When the bi-laminar disc is converted into the tri-laminar disc.
When is the bi-laminar disc formed ?
week 2
What are the layers and sacs preset in the bi-laminar layer ?
Epiblast and hypoblast
Amniotic sac and yolk sac
When is the tri-laminar disc formed ?
week 3
What are the layers present in the tri-laminar layer ?
Ectoderm, Mesoderm and Endoderm
What week does the primordial gut tube form ?
week 4
What layer of the tri-laminar disc forms the primordial gut tube ?
Endoderm
At which end of the primitive gut tube is the esophagus formed ?
The cranial end
On which wall of the foregut do the lung buds develop ?
The ventral wall of the foregut
What is esophageal atresia ?
When the tracheoesophageal septum divides incorrectly causing incomplete separation of the esophagus and the trachea
Around which week does the stomach begin to form?
week 4
How is the stomach formed?
The foregut rotates anterior posterior 2 times to create the stomach
How many rotations are required for the stomach to be created ?
2
What do these rotations that the stomach must complete create ?
The greater and lesser curves
The dorsal mesentery develops into which upper GI organ ?
The spleen
The ventral mesentery develops into which upper GI organ ?
The liver
Wht ca be found posterior to the stomach ?
The lesser sac
What makes the C-shape of the duodenum thats seen in the adult abdomen ?
The rotation of the stomach also rotates the duodenum giving it its typical C-shape
What parts of the bowel are formed from the primitive midgut tube ?
The duodenum
jejuno-ileum ad proximal colon
What week does the mid gut undergo rotation ?
Around week 6
What kind of rotation does the midgut undergo ?
90 degrees clockwise
If the ventral bud fails to migrate around the duodenum correctly then this creates____
an annular pancreas
What is physiological herniation and why does the midgut undergo this process?
When the mid gut herniated out into the umbillicus in order for the gut to grow in length.
At which week does the physiological herniation stop ?
Around week 10 the gut tube returns to the inside of the embryo when there is more room inside the abdomen.
What is an omphalocele ?
Herniation of abdominal viscera through a large umbilical ring or failure of retraction of umbilical ring. Usually covered in a layer of amnion.
What is Gastrochisis ?
Where the contents of the midgut herniate right through the body wall into he amniotic cavity. The contents will not be covered by a layer of peritoneum or amnion.
What is Meckel’s Diverticulum ?
Remnants of a vitaline duct within the bowel
The primitive hindgut develops into which adult structures ?
1/3 of the distal transverse colon, the descending colon, the sigmoid colon, the upper part of the rectum and the anal canal.
Which primitive layer lines the bladder and the urethra ?
The endoderm
The conditions: Urorectal fistula Rectovagial fistula Rectoanal atresia are all caused by which defect ?
In complete separation of the hindgut from the urogenital sinus by the urorectal septum
