Embryology Flashcards
(38 cards)
what is the Primitive gut derived from
Made from the endoderm
What does primitive gut consist of
epithelial lining, hepatocytes of liver & endocrine and exocrine cells of pancreas) and visceral mesoderm (muscle & connective tissue
What does fore gut consist of (7)
- Oral pharyngeal membrane—>liver bud
- Coeliac artery
- Oesophagus
- Stomach
- Liver
- Biliary apparatus
- 1/2 of duodenum
What does midgut consist of (8)
- Liver bud —> 2/3rds traverse colon
- Superior mesenteric artery
- Distal 1/2 of duodenum
- Jejunum
- Ileum
- Appendix
- Ascending colon
- Right 2/3rds of transverse colon
What dos the hind gut consist of (6)
- 2/3rds transverse colon —> cloacal membrane
- Inferior mesenteric artery
- Left 1/3rd of transverse colon
- Sigmoid colon
- Rectum
- Anal canal
what is the Hepatic diverticulum
A cellular expansion of the foregut which gives rise to the parenchyma (functional part) of the liver
When does the hepatic diverticulum appear and how`
Appears in the middle of the 3rd week as an outgrowth of the endodermal epithelium at the distal end of the foregut (duodenum)
What does the liver bud contain in embryology
-The liver bud contains rapidly proliferating cells that penetrate the septum transversum (thick mass formed in the embryo that gives rise to parts of the thoracic diaphragm & ventral mesentery)
how does the bile duct form
The bile duct forms when the connection between the liver diverticulum and the foregut narrows
how is the gallbladder and cystic duct formed
A small ventral outgrowth develops from the bile duct which gives rise to the gallbladder & cystic duct
What does the further growth of the liver bud allow
Further growth of the liver bud allow the epithelial liver cords to intermingle with the umbilical & vitelline veins, forming the hepatic sinusoids
What forms the lining of the biliary ducts
Liver cords differentiate into hepatocytes (liver parenchyma) and form the lining of the biliary ducts
What happens in the 6th week to the mesoderm why is this important
In the sixth week the mesoderm of the ventral mesentery gives rise to haematopoietic cells, Kipper cells & connective tissue cells
haematopoiesis is an important function of the liver at this stage since it acts as the “bone marrow” in the production of white blood cells & red blood cells
At the 10th week, the liver weight is about 10% of the total body weight why
this is due to the presence of large numbers of sinusoids and involvement of the liver in haematopoietic function
At birth, the liver weighs about 5% of the weight due to the existence of what
small numbers of haematopoietic islands in the liver, and its haematopoietic function is greatly reduced
Hepatic cells start production of bile when
at the age of the 12th week
what happens to the haematopoietic function during the last 2 months of intrauterine life
The haematopoietic function subsides during the last 2 months of intrauterine life
What happens to the left umbilical vein after birth
obliterates to form the LIGAMENTUM TERES
What happens to the ductus venosus after birth
The ductus venosus undergoes fibrosis leaving a remnant called the LIGAMENTUM VENOSUS
How does the stomach first rotate
1st it rotates 90 degrees along a longitudinal axis (left now becomes anterior)
What happens when the stomach rotates 90 degrees along a longitudinal axis
The posterior wall grows quicker (now on the right side) this gives the greater curvature
After the original rotation how does the the stomach now rotate
2nd it rotates around the anterior posterior axis - the pyloric region of the stomach moves right and up an the cardiac region of the stomach moves left & down
Where does the pancreas sit
Pancreas is located retroperitoneally across the posterior abdominal wall, it sits behind the stomach across the back of the abdomen
What are the two types of glands the pancreas is made up of
Exocrine
and endocrine
