Embryology

Question 1

Average fetal age

Answer 1

38 weeks from conception to birth

Question 2

Gynecological age

Answer 2

Timing from LMP, usually about 40 weeks for gestational age.

Question 3

Embryonic Period

Answer 3

First 8 weeks. All major organs formed.

Question 4

Fetal period

Answer 4

Remaining 30 weeks. Organs grow larger and become more complex.

Question 5

Zygote

Answer 5

The cell that forms when ova and sperm fuse.

Question 6

Where does fertilization occur?

Answer 6

In the fallopian tube.

Question 7

What is the zygote (morula)called when it enters the uterus?

Answer 7

Blastocyst

Question 8

Inner cell mass forms?

Answer 8

The embryo

Question 9

Trophoblast forms?

Answer 9

the placenta

Question 10

When does implantation take place?

Answer 10

6 days post conception. Trophoblast erodes uterine wall. “Spotting” may occur.

Question 11

Bilaminar embryonic disc

Answer 11

Gives rise to the whole body. Gives rise to trilaminar disc which forms the 3 layers.

Question 12

What are the 3 layers?

Answer 12

Ectoderm, endoderm, mesoderm

Question 13

Ectoderm and endoderm form?

Answer 13

epithelial tissues

Question 14

Mesoderm forms?

Answer 14

Mesenchyme tissue. Tend to form muscle

Question 15

When does the neural tube close?

Answer 15

begins at week 3, closes by week 4. folic acid is important for this.

Question 16

Ectoderm

Answer 16

Forms epidermis, hair, nails and skin glands. Brian and spinal cord. Neural crest

Question 17

Mesoderm

Answer 17

Vertebrae and ribs, Kidneys, gonads, connective tissue, heart, blood vessels, walls of digestive and resp tracts.

Question 18

Endoderm

Answer 18

Epithelial lining and glands of digestive and respiratory tracts

Question 19

When does the heart start pumping?

Answer 19

Around 1 month

Question 20

During what period do most gross structural birth defects take place?

Answer 20

weeks 3-8. 3rd and 4th weeks are particularly vulnerable.