GI embryology Flashcards
What 2 planes does embryonic folding in 4th week occur? Why? Folding in horizontal plane forms what? Medial plane?
Horizontal and medial planes
Differing rates of growth
2 lateral body folds
Cranial and caudal folds
Primitive gut tube from what layer? During what week does oropharyngeal membrane rupture to form the mouth? What week does cloacal membrane future–> anal canal?
Endoderm
4th week
7th week
What are pharyngeal arches part of? Extends from what to what? When do these develop?
Foregut
Oropharyngeal membrane–> resp diverticulum
4th and 5th week
What are pharyngeal arches formed from? Covered externally and internally from what?
Masses of mesenchymal tissue invaded by cranial neural crest cells
Externally= from endoderm–> clefts, internally= ectoderm–> pouches
1st arch innervated by what? What muscles? What bones?
Mandibular nerve- V3
Mastication, tensor tympani, digastric, myolohyoid
Maxilla, mandible, incus, malleus
2nd arch innervation? Muscles? Bones?
Facial nerve
Facial expression, stapedius, stylohyoid
Stapes, styloid, lesser horn of hyoid cartilage
3rd arch innervation? Muscles? Bones?
Glossopharyngeal nerve
Stylopharyngeus of pharynx
Body and greater horn of hyoid cartilage
4th arch innervation? Muscles? Bones?
Superior laryngeal nerve of vagus nerve
Cricothyroid
Thyroid and epiglottic cartilages
6th arch innervation? Muscles? Bones?
Recurrent laryngeal nerve of vagus nerve
All muscles except cricothyroid
Cricoid cartilage, arytenoid cartilages, corniculate and cuneiform cartilages
What septum separates the resp diverticulum from dorsal part of foregut? Foregut divided into what? Oesophagus is what initially but does what?
Trancheoesophageal septum
Ventral resp primordium and dorsal oesophagus
Short but lengthens rapidly with descent of heart and lungs
Where is ventral mesentery only present? Midgut and hindgut only what?
Only in foregut- terminal oesophagus, stomach and upper duodenum
Only dorsal mesentery
Ventral mesentery is derived from what? Free lower margin contains what? Liver develops where?
Septum transversum
Hepatic artery, portal vein and bile duct
In ventral mesentery- divides it into lesser omentum and falciform ligament
Stomach appears in foregut in what week? Does dorsal or ventral wall grow faster?
4th week
Dorsal grows faster- forms greater and lesser curvatures
During what week does stomach undergo 90 degrees clockwise rotation? During what week does stomach and duodenum rotate about a ventrodorsal axis?
7th week- produces lesser sac
8th week- pulls stomach upwards and duodenum into C-shape
Rotations results in what? Ventral mesentery forms what? Anterior and posterior folds of greater omentum fuse to form what?
Thinning of dorsal mesentery–> greater omentum
Lesser omentum
One thick sheet formed from 4 layers of peritoneum
During what week does hepatic diverticulum appear? When does bile duct form? What gives rise to the gallbladder and cystic duct?
3rd week- as outgrowth of endodermal epithelium at distal end of foregut
When connection between liver diverticulum and foregut narrows
Small ventral outgrowth from bile duct
Further growth of liver bud allows epithelial liver cords to intermingle with what? Liver cords differentiate into what?
The umbilical and vitelline veins–> hepatic sinusoids
Hepatocytes- form lining of biliary ducts
During what week does mesoderm of ventral mesentery give rise to haematopoietic cells, Kipper cells and connective tissue cells?
6th week
At 10th week, liver what % of total body weight? % at birth? Cells start bile production at what age? Haematopoietic function subsides when?
10%
5%
12th week
During last 2 months of intrauterine life
Where does pancreas develop from? Where is each bud?
Endodermal lining of duodenum as dorsal and ventral buds
Ventral bud from ventral mesentery
Dorsal bud from dorsal mesentery
When the duodenum rates and becomes C-shaped, what happens? What fuses together?
The ventral bud and entrance to common bile duct in duodenum are shifted dorsally- lies below and behind dorsal bud
Parenchyma and duct systems of both buds fuse together
The ventral bud forms what? Dorsal bud forms what?
Uncinate process and inferior of head
Rest of pancreas
Main pancreatic duct formed from what? Islets of Langerhans from what during what month of fetal life? Insulin secretion begins when? Pancreatic connective tissue from what?
Union of ventral pancreatic duct with distal part of duct of dorsal bud
Parenchyma of pancreas at 3rd month
At 5th month
Visceral surrounding mesoderm
