Embryology

Question 1

What are the 3 main embryonic components?

Answer 1

• Ectoderm
• Mesoderm
• Endoderm

Question 2

What is the ectoderm?

Answer 2

The epithelium of extreme ends of the tract, including outer epithelium and the nervous system

Question 3

What is the mesoderm?

Answer 3

It becomes the musculoskeletal system including smooth muscle and produces embryonic mesenchyme when it differentiates (ie. the loose tissue in an embryo that will then give rise to various different tissues)

Question 4

What is the endoderm?

Answer 4

It becomes the intestinal epithelium

Question 5

What type of fission divides the fist cell that will eventually become the embryo?

Answer 5

Binary fission

Question 6

How is the third cell layer formed?

Answer 6

Once the first two cell layers form invagination of the surface layer forms the third.

Question 7

What are the 4 types of tissue in embryology?

Answer 7

1. Epithelial = skin, lungs, GIT lining
2. Neural = nervous system, derived from the embryonic ectoderm so named neuroectoderm
3. Contractile = all muscles deprived from the embryonic mesoderm
4. Connective = anything not included above, also derived from embryonic mesoderm

Question 8

What is the difference between the epithelium, the ectoderm and the endoderm?

Answer 8

Epithelium: fetal/neonatal/adult term for cell layers against the outside world
Ectoderm: Upper layer of embryo that will become skin and nervous system
Endoderm: Lower layer of embryo that becomes GIT lining

(ecto and endo become epithelium)

Question 9

What is the name given to the cells that line the blood vessels ad where do they originate from?

Answer 9

Endothelial cells but originate from the mesoderm NOT the endo or ectoderm

Question 10

Where does all connective tissue originate from?

Answer 10

The mesoderm ie. middle layer