Embryology Flashcards
What gene is a transcription factor for establishing left sidedness?
PTX2
Define gastrulation
formation of germ layers
What structures develop from embryonic ectoderm?
Skin
CNS
PNS
Ear
Nose
Throat
What structures develop from embryonic endoderm?
Epithelial lining of respiratory system
GIT
Glands
Liver
Pancreas
Urinary bladder
What structures develop from embryonic mesoderm?
Muscles
Bones
Cartilage
Urogenital system
What week is the gut tube formed?
During 3rd and 4th
What gives rise to parietal and visceral mesoderm?
Lateral plate mesoderm
What is the gut tube closed by at its cranial end?
Oropharyngeal membrane
What is the gut tube closed by at its caudal end?
Cloacal membrane
What secretes sonic hedge hog cells?
Gut endodermal cells
What is the function of SHH?
Organisation of gut
Where does ventral mesentary form from?
Caudal end
What mesentery hangs gut tube from body wall?
Dorsal
Where does the oesophagus develop from?
The cranial part of the gut tube
What is the function of the Tracheo-oesophageal septum
Divides oesophagus from trachea
What does the lung bud develop from?
Outgrowth of the ventral wall of the foregut
What forms the stomach?
Foregut caudal of oesophagus dilates to form the stomach
What part of the stomach does the left vagus supply?
Anterior wall of stomach
What part of the stomach does the right vagus supply?
Posterior part of stomach
What is the stomach attached to the dorsal and ventral wall by?
A mesentery called mesogastrium
What forms the lesser sac?
Rotation along the longitudinal axis pulling the dorsal mesentery to the left
What is the duodenum formed from?
Caudal part of the foregut
Cranial part of the midgut
What artery supplies the duodenum below the opening of the bile gut?
Superior mesenteric artery
What artery supplies the duodenum above the opening of the bile duct?
Coeliac trunk
Is the duodenum retroperitoneal or intraperiotoneal?
Retroperitoneal except the duodenal cap
What gives rise to the gallbladder?
Liver bud
When is the liver bud formed?
Week 3
What liver parts are endodermal origin?
Hepatocytes
Biliary epithelial
What liver and biliary apparatus are mesodermal origin?
Kupffer cells
Haemotopoietic cells
Connective tissue
What does the falciform ligament and momentum develop from?
Ventral mesentary
When is bile formed?
12th week
What is the origin of the spleen?
mesoderm
What connects the spleen and kidney?
splenorenal ligament
What happens to the spleen in weeks 15 to 17 of gestation?
Colonised by T-lymphocytes
What happens to the sleep in week 23 gestation?
The b-cell precursors arrive and spleen starts it’s lymphoid function
What forms the head of the pancreas?
Duodenum rotates so the ventral bud also moves closer to the dorsal bud
When does the pancreas and spleen form?
Week 5
When does the head of the pancreas form?
Week 6
What is the result of incomplete separation of the lung bud?
Oesophageal atresia
Tracheo-oesophageal fistula
Give examples of developmental anomalies in the foregut
Double gallbladder
Stricture of duodenum
Annular pancreas
Where does the midgut extend from?
From opening of bile duct into the duodenum to proximal 2/3rds of the transverse colon
What way does the primary intestinal loop rotate?
Anti-clockwise
What happens to the primary intestinal loop in week 6?
Physiological herniation of intestinal loop
What does the Vitelline duct connect?
Ileium with yolk sac
When do the intestinal loops move back into abdominal cavity?
Week 10
What week does the cecal bud develop?
Week 6
What does the cecal bud form from?
Caudal part of loop S. intestine forms
What happens to the midgut loop?
Elongates needs will differentiate into different parts of intestines
What are some common developmental abnormalities of the midgut?
Stenosis
Malrotation
What is omphalocele?
Failure of retraction of herniated intestinal loop though umbilical ring at week 10
What may vitelline duct form if it persists?
Fistula
Cyst
Ligament
Meckel’s diverticulitis
What parts of the hindgut are ectodermal origin?
Lower part of anal canal and anal orifice
When does the cloacal membrane rupture?
week 7
What part of the anal canal is endodemral origin?
Cranial part
What part of the anal canal is ectodermal origin?
Caudal anal canal
What are some common hindgut developmental anomalies?
Urorectal fistula
Rectovaginal fistula
Rectoperineal fistual
Imperforated anus
