Zusammenfassung der Ressource
Fertilized cell early development
- Week 2
- Trophoblast forms and has
2 layers:
- 1. cytotrophoblast (makes
cells)
- 2. syncytiotrophoblast: forms syncytium = responsible for
invasion of the blastocyst into the uterine endometrium and
production of hormones
- the germ disc (embryoblast) forms and has 2 layers:
- 1. epiblast
- 2. hypoblast
- Three cavities form:
- 1. amniotic = dorsal to epiblast
- 2. yolk sac = ventral to hypoblast
- Later in the week...
- 3. chorionic cavity forms
- Extraembryonic mesoderm
forms around the outside of the
amnion and yolk sac splits into
two layers:
- 1. somatic
- 2. splanchnic
- Week 1
- 1. Fusion of pronuclei
- 2. Blastomeres divide
- 3. Morula forms
- 4. Blastocyst forms
- Consists of a fluid filled cavity, an inner cell mass =
embryo, and an outer cell mass = trophoblast (fetal
contribution to the placenta)
- Week 3
- Gastrulation
- The process of making the 3 germ layers:
- ectoderm
- skin, CNS, PNS, eyes, internal
ear, neural crest cells(bones &
connective tissue of the face
and part of the skull)
- mesoderm
- blood, bones, connective
tissue, urogenital system,
cardiovascular system
- endoderm
- gut, gut derivatives
(liver, pancreas, lungs,
etc.), parenchyma of
glands
- Notochord formation
- helps induce the CNS
- eventually forms the nucleus
pulposus in intervertebral discs.