Body Folding Flashcards
Week 4
- primitive streak becomes the neural tube
- 3 germ layers become prolific and populate
- lots of gene expression
- lots of mitosis
- somites
- neural crest cells
- gut tube formation
- muscle specification
Body folding results in the creation of which two structures?
1.) Head and tail region
2.) Vertebral body form
What factors drive folding?
1.) Cell shape changes
2.) Increased number of cells
3.) Chemical communication
What’s the purpose of body folding?
- neurulation begins
- cranial neuropore closes
- caudal neuropore closes and primitive streak disappears
Body folding details
- yolk sac diminishes
- body takes on cylindrical shape with regions
- folds of tissue fuse and meet with each other
- folds on 2 planes
Body takes on cylindrical shape with these regions
1.) Cranial (head)
2.) Caudal (tail)
3.) Lateral body fold
Cranial (head) region
view sagittal
Caudal (tail)
view sagittal
Lateral body fold
view xs
What are the 2 planes during folding?
1.) Horizontal plane
2.) Median plane
Horizontal plane
Lateral body folds
Median plane
Cranial and caudal folds
Cardiogenic area (heart)
horseshoe-shaped mesodermal tissue
Septum transversum
separates the coelom into thoracic and abdominal cavities
- ventral mesentery of stomach and duodenum
- day 22
________ growth of the neural plate causes the cranial rim to fold under
Forward
What does forward growth form?
ventral surface of future face, neck, and chest
Forward growth pushes the oropharyngeal membrane to the region of the future ______
mouth
Forward growth pushes the cardiogenic area and septum transverse toward the future ______
chest
_____ growth due to lengthening of neural tube, and somites overgrow caudal rim of yolk sac
caudal
Caudal portion folds under traveling _______
cranially
What does the caudal portion form?
ventral surface and meets with neck of yolk sac
What happens to the yolk sac during caudal growth?
it lengthens and constricts
In caudal growth, the roots of the connecting stock contains a slender endodermal hindgut diverticulum called what?
allantois
Lateral growth
- the embryonic disc flex sharply ventrally constricting and narrowing the neck of the yolk sac
During lateral growth, the lateral sides meet up and “zip” toward the location of the future _________
umbilicus
During lateral growth, all 3 germ layers ______ and _____
meet; fuse
T/F During lateral growth, the tube within a tube plan is established
True
Schisis
split or cleave
Gastroschisis
the bowel herniates through an opening in the body wall and is not contained within a membranous sac
Omphal
umbilicus
