Embryology of the GI Flashcards
When does fertilisation to implantation occur?
Week 1
When does the bilaminar germ disk form?
Week 2
When does the trilaminar germ disk form?
Week 3
When does organogenesis occur?
Week 3 to 8
What is organogenesis?
The production and development of the organs of an animal or plant
What is responsible for establishing the left sideness of an organ or body body?
Genes such as the PTX2 gene
What does mutations in the PTX2 gene result in?
Dextrocardia because it is responsible for establishing the left sideness of an organ
What are the general 3 phases of embryological development?
1) Growth/proliferation (cell division and elaboration of products)
2) Morphogenesis (development of shape, size of a particular organ or part of the body)
3) Differentiation (maturation of physiological processes)
What does exposure to teratogens during weeks 4 to 8 lead to?
Major congenital conditions
What is gastrulation?
Process of bilaminar embryonic disc being converted into trilaminar disc
What are the 3 layers of the trilaminar disc?
Ectoderm
Mesoderm
Endoderm
What does the ectoderm go onto form?
Skin (epidermis, hair, nails)
CNS
PNS
Sensory epithelia of the eye
Ear
Nose
Liver (except parenchyma)
Urinary bladder
What does the endoderm go onto form?
Epithelial lining of renal system
GI tract
Liver
Pancreas
Thyroid
Parathyroid parenchyma
Urinary bladder
What does the mesoderm go onto form?
Muscle
Bones
Cartilage
Dermis
Vascular system
Most of the CVS connective tissue
Blood cells
Bone marrow
Urogenital system except bladder
Spleen
Suprarenal gland cortex
What are the 3 parts of the digestive system?
Foregut
Midgut
Hindgut
What gives rise to the parietal and visceral mesoderm?
Lateral plate mesoderm
When does the gut tube form?
During the 3rd and 4th week from the endoderm lining the yolk sac
What is the gut tube closed by at the cranial end?
Oropharyngeal membrane
What is the gut tube closed by at the caudal end?
Cloacal membrane

What does the foregut form?
Oesophagus
Stomach
Omental bursa (lesser sac)
Duodenum
Liver and bilary apparatus
Spleen
Pancreas
Explain the development of the oesophagus?
1) Develops from cranial part of primitive gut tube
2) Laryngo-tracheal diverticulum (lung bud) develops from the ventral wall of the foregut
3) Tracheo-oesophageal septum divides the foregut tube into the trachea and oesophagus

What is the lung bud also known as?
Laryngo-tracheal diverticulum

What divides the foregut tube into the trachea and oesophagus?
Tracheo-oesophageal septum

When does the stomach develop?
4th week















