Body Cavity Development Flashcards
Deuterostomes?
- second mouth
- we from a tube with ectoderm on outside
- endoderm inside
- mesoderm in between
Coelom? what forms it?
- body cavity
- forms within mesoderm
What layer controls what we bring in?
Endoderm
-nutrients, air
Oropharyngeal membrane?
- cranial end where ectoderm and endoderm come in contact
- will become mouth
Cloacal membrane?
- caudal end where ectoderm and endoderm come in contact
- will become anus
What axes do the three layers fold in?
- lateral
- cranial-caudal
Lateral folding starts when?
3rd week
Early formation of Coelom (day 19)?
-lateral plate mesoderm forms small openings called intercellular clefts
Splitting of lateral plate mesoderm (day 20)?
- intercellular clefts separate the somatic (parietal) mesoderm from splanchnic (visceral) mesoderm
- this space is called intraembryonic coelom or embryonic body cavity
Mushroom stage (day 21)?
- amniotic sac begins to surround embryo
- yolk sac begins to narrow
- intraembryonic and extra embryonic coeloms still connected
Isolation of embryonic coelom (day 24)?
- somatic mesoderm encompasses intraembryonic coelom
- splanchnic mesoderm surrounds nascent gut tube to form dorsal and ventral mesenteries
- gut tube still connected to yolk sac
Body cavity closure (end of 4th week)?
- fusion of somatic (parietal) mesoderm to form ventral body wall
- splanchnic (visceral) mesoderm of ventral mesentery breaks down to form continuous left and right intraembryonic coelom
- gut contained within splanchnic mesoderm and is connected to dorsal body wall by dorsal mesentery
Allantois?
- forms part of urogenital system
- hindgut
Angiogenic cell cluster?
- future heart
- more cranial and distal to oropharyngeal membrane
Cranial caudal folding (day 22)?
- folding of endoderm at cranial and caudal ends
- foregut
- hindgut forms
- pericardial cavity forms under cranial portion
- septum transversum adjacent to heart and gut tube
Site of lung bud formation?
foregut