General embryology Flashcards
List the three pre-embryonic stages of development
- Zygote (fertlised ovum)
- Morula
- Blastocyst
When does a blastocyst become an embryo?
Day 10-12
When does an embryo become a fetus?
8 weeks
Where does the trophoblast arise from? What do these cells form?
From the outer layer of the blastocyst, and they form a large part of the placenta
What two cavities form from the inner cell mass of the blastocyst? What divides these cavities?
The ambion, and the yolk sac, either side of the embryonic plate.
What arises from the embryonic plate?
The ectoderm and endoderm
What does the mesoderm arise from?
The ectoderm
Other than the mesoderm, what forms from the ectoderm early on?
The neural tube
What are the terminal products of the ectoderm?
Skin, appendages
Neural tissues
What epithelia are formed from ectoderm? What do other epithelia arise from?
Skin, lining of the mouth and anus, nostrils, sweat glands and hair follicles.
Other epithelia arise from the endoderm.
What part of the tooth arises from ectoderm?
What part of the tooth arises from neural crest cells?
Tooth enamel - ectoderm
Dentine and cementum - neural crest cells
List the ten end products of neural crest cells
- Parafollicular (C) cells of the thyroid
- Chromaffin cells of the suprarenal medualla
- Melanocytes
- Post root ganglia of spinal nerves and the corresponding ganglia of cranial nerves
- Autonomic ganglia
- Neuroglia, Shwann cells
- Meninges
- Bones of the skull and face
- Sclera and choroids of eye
- Dentine and cementum of teeth.
What major embryological structure does gastrulation form?
Gastrulation creates a mesodermal layer between the endoderm and ectoderm.
What forms at the same time that gastrulation is occuring
The neural tube
What extends beneath the neural tube from the base of the head to the tail?
The notochord