GIT Embryology Flashcards
What happens in week 1
Fertilisation to Implantation
5-6 days
what happens in week 2
Bilaminar germ disk formation
Everything in 2
Establishment of body axis
PTX2 gives left hand sideness
What happens in week 3
Trilaminar germ disk formation
What happens in week 3 - 8
Organogenesis
What different structures originate from ectoderm
CNS,PNS
Epithelia of eye, ear, nose
SKin
Adrenal medulla
NESA
What structures orginate from embryonic endoderm
Epthelia of Resp
GIT
glands
liver
pancreas
thyroid
bladder
What structures originate from mesoderm
muscles
bones
cartiladge
dermis
vascular system
spleen,liver
When is the gut tube formed
During 3rd and 4th week
Lateral p.m -> parietal & visceral mesoderm
Parietal lines body cavity
Visceral lines gut tube
What is the gut tube closed by
Oropharyngeal membrane at Cranial
Cloacal membrane at Cudal end
What is the mesentery
Mesodermal origin
Enclose organs
Hangs gut tube
Where does the oeophagus develop from
Cranial part of gut tube
How is the stomach formed
Foregut caudal to oesophagus dilates = stomach
Week 4
Creates GC and LC
Where are the greater and lesser omentum located
How is the duodenum formed
From caudal part of foregut
Cranial part of midgut
-Retropertoneal except duodenal cap
When is liver bud formed
Week 3
What structures are endodermal in origin and mesodermal in origin
Endodermal origin:
Hepatocytes, biliary epithelia
Gall bladder & cystic duct
Mesodermal origin:
Kupffer cells
haematopoeitu and connective tissue
What is the origin of spleen
What happens in weeks 15-17 and 23
Mesodermal origin
15-17: T-lymphocytes
23: B-cell arrives- lymphoid function begins
What is the origin of pacreas
Endodermal
Give an example of developmental anomaly
Incomplete seperation of lung bud
Oesophageal atresia and tracheooesophageal fistula
Duplication of galbladder
Midgut
How is the primary intestinal loop formed
Anti-clockwise rotation
Physical herniation of loop
Vitelline duct connects with ilium of yolk sac
What are some of the midgut anomalies
Abnormal rotation or reversed rotation
What happens during a omphalocele
Failure of retraction of herniated intestinal loop
Week 10
What problem can occur with remnants of vitelline duct
May form fistula/cyst/ligament
What does atrasia and stenosis look like
Hindgut development
What parts of the hindgut are endodermal or ectodermal in origin
Endodermal:
Distal 1/3rd transverse colon
Descending colon
Sigmoid colon
rectum
Ectodermal:
Lower anal canal & anal orrifice
What are the different anal canal origins
Cranial part -> endodermal
Caudal part-> ectodermal
cloacal membrane ruptures at 7th week gestation
What is the blood supply of hindgut
What are the developmental anomalies in hindgut
