gastrulation + neurulation Flashcards
exam 1
formation of the three germ layers
gastrulation
what is the first step in gastrulation?
formation of the primitive streak from the caudal end to the head end
what happens after the formation of the primitive streak
there is a waterfall like rush of ectoderm cells through it and this will become the mesoderm
what does the mesodorm form?
notochord
what does the notochord do?
helps define the major axis of our bodies and later becomes the invertebral disk
what is the process of neurulation?
process in which the neural plate folds to form the neural tube and crest
neural plate is a
flat piece of the ectoderm
what induces the formation of the neural tube?
notochord
mesoderm cells differentiate into
somites
somites
precursor of the axial skeleton/ skeletal muscles
somitogenesis
process of segmentation of the paraxial mesoderm
how does somitogenesis occurs?
begins cranially and extends caudally adding a somite pair and the process is sequential
neural crest cells become the
PNS
neural tube becomes the
CNS
lateral late mesoderm
- splanchic
- somatic
- extra-embryonic
intermediate mesoderm
- kidney
2. Gonads
paraxial somitic mesoderm
- sclerotome
- syndotome
- myotome
- endothelial cells
- dermatome
syndotome
tendons
sclerotome
cartilage
dermetome
skeletal muscle
What is so special about myotomes?
split by the tranverse processes
Myotomes are split into two catergories
- epimere
2. hypomere
epimere
dorsal/ back musculature
hypomere
ventral body and all limb musculature
faulty crest migration—-? vagal crest into distal gut
DiGeorge
bowel nerve cell are not present—-> no neural crest migration leading to a congenital megacolon
Hirchspung’s dx
anterior failure to close neural tube
anencephaly
posterior failure to close neural tube but there is no potrusion of fluid
spina bifida occulta
spina bifida cystica which has swelling of the meninges
meningocele
spina bifida cystica which has swelling of the meninges and spinal cord
meningomyelocele