FORMATION GERM LAYERS Flashcards
(21 cards)
Epiblast divided into
Amniotic ectoderm
Embryonic epiblast
Formation of yolk sac endoderm
Embryoblast ➡️ hypoblast ➡️ extraembyonic endodrm ➡️ yolk sac endoderm
Embtyonic epiblast divided into
Embyonic ectoderm
Primitive streak
How bilaminar germ disc is formed
Epiblast + hypoblast
Decidua reaction causes….. 1) 2)
Change in endometrial stroma
Ready for implantattion
Synonym of primitive yolk sac cavity
Exocoelemic cavity
What is primitive streak
Linear groove in midline of caudal half, bilaminar germ disc
What is primitive node
Cephalic end of primitive streak
Functions of primitive streak
- 1st landmark, reveals polarity embryo
- Identify embryonic axes, surface and end
What is notochord
Solid cord of intraembyonic mesoderm
At midline trilaminar germ disc
extend from primitive node ➡️ prechordal plate
Functions of notochord
- Basis of axial skeleton
- Induce overlying ectoderm dy/dx ➡️ neuroectoderm
- Form nuclues pulposus
What is neurenteric canal
Small canal at primitive pit
form temporary connection between amniotic cavity and yolk sac
What is buccopharyngeal membrane
Plate that cranial to cephalic end of notochord
What BP membrane composed of
Tightly adherent layers of ectoderm + endoderm
Neural plate
Thickened plate of ectoderm between primitive pit and BC membrane
Neural folds
Lateral edges of neural plate that are elevated
Neural groove
Area between folds that are depressed
Neural tube
Folds grow medially ➡️ fuse midline ➡️ detach from surface
Anterior neuropore
Open cranial end of neural tube
Posterior neuropore
Open caudal end
What is neural crest
Longitudinal ridge at lateral border of neuroectoderm
