Mod 4 - Embryology & Development - Part 2

Epiblast

becomes the embryo

Amniotic cavity

Forms inside inner cell mass and surrounded by layer cells called the amnion or amniotic sac

Embryonic disk

composed of to layers inside the blastocele: epiblast and hypoblast

Hypoblast

extraembryonic membranes

3 germ layers of epiblast

Endoderm, mesoderm, ectoderm

Gastrulation

formation of germ layers

yolk sac

forms inside blastocele from hypoblast

Primitive steak

Thickened region of cells; will then know which side is the head and tail

Endoderm

Inner layer; Forms lining of digestive tract and derivatives

Mesoderm

Middle layer; Forms tissue such as muscle, bones, blood vessels

Ectoderm

Outer layer; forms skin nervous system (brain)

Notochord

from mesodermal cells; involved in induction and signals ectoderm to make neural plate

oropharyngeal membrane

Membrane at the cephalic end of the embryo that is the location of the future primitive mouth.

cloacal membrane

membrane at caudal end of embryo that is the location of future anus

Neural tube

forms the brain and spinal cord

Neural crest

Sensory and PNS; connective tissue of the head

Neural tube steps

1. Formation of neural plate

2. formation of neural groove

3. neural folds form neural crest

4. Neural crest cells begin to form

5. neural crest cells fuse

somites

found in mesoderm; Becomes vertebral column, ribs skeletal muscles