When does fertilisation to implantation occur?
When does the bilaminar germ disk form?
When does the trilaminar germ disk form?
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?
Dextrocardio 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?
What does the ectoderm go onto form?
Skin (epidermis, hair, nails)
Sensory epithelia of the eye
Liver (except parenchyma)
What does the endoderm go onto form?
Epithelial lining of renal system
What does the mesoderm go onto form?
Most of the CVS connective tissue
Urogenital system except bladder
Suprarenal gland cortex
What are the 3 parts of the digestive system?
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?
What is the gut tube closed by at the caudal end?
What does the foregut form?
Omental bursa (lesser sac)
Liver and bilary apparatus
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?
What divides the foregut tube into the trachea and oesophagus?
When does the stomach develop?
Explain the development of the stomach?
1) Foregut dilates to form the stomach
2) Differential growth of the stomach wall creates the greater and lesser curvatures
3) Stomach rotates and adapts its shape to fit in with the other developing organs
4) Undergoes a 90o rotation around its own longitudinal axis
5) Undergoes an anterio-posterior roation to create final adult position
What is the stomach attached to the dorsal and ventral wall by?
Mesogastrium (a mesentery)
Explain the development of the omental bursa (lesser sac)?
1) Stomach is attached to dorsal and ventral wall by mesogastrium
2) Rotation along its longitudinal axis pulls the dorsal mesentery to the left creating the omental bursa (lesser sac)
When the stomach rotates on its longitudinal axis, what direction is the ventral mesogastrium pulled in?
What is the duodenum formed from?
Caudal part of the foregut and cranial part of the midgut
Explain the development of the duodenum?
1) Formed from the caudal part of the foregut and the cranial part of the midgut
2) As the stomach rotates the duodenum becomes c-shaped and also rotates
3) Duodenal cap retains its dorsal mesentery but the rest of it is retroperitoneal following the fusion of the dorsal mesentery with the peritoneum of the posterior abdominal wall