Embryology

Question 1

Define Embryology

Answer 1

Study of the origin and development of an organism

Question 2

How long is the “fetal” age?

Answer 2

38 weeks

Question 3

How long is the “gestational” age?

Answer 3

40 weeks

Question 4

How long and what defines the “embryonic” period?

Answer 4

First 8 weeks

All major organs formed

Question 5

How long and what defines the “fetal” period?

Answer 5

Remaining 30 weeks

Organs grow larger and increase in complexity

Question 6

Define Ovulation

Answer 6

Egg released into the peritoneal cavity

Question 7

Define Fertilization

Answer 7

Occurs as egg travels down the fallopian tube

Question 8

Define Zygote

Answer 8

The cell that forms when the ova and sperm fuse

Question 9

Define Cell Division

Answer 9

Begins immediately as the zygote travels down the fallopian tube and into the uterus

Question 10

What occurs during the first week after conception?

Answer 10

Zygote divides repeatedly
Daughter cells = blastomeres
Morula
Blastocyst

Question 11

Define Morula

Answer 11

Solid cluster of 12-16 blastomeres at about 72 hours

Question 12

When occurs on day 4 post conception?

Answer 12

Morula enters uterus and takes up fluid becoming a blastocyst

Question 13

Types of Cells in the Blastocyst Stage

Answer 13

Inner cell mass

Trophoblast

Question 14

Define Inner Cell Mass

Answer 14

Forms the embryo

Question 15

Define Trophoblast

Answer 15

Layers of cells surrounding the cavity which helps form the placenta

Question 16

What occurs on day 6 post conception?

Answer 16

Implantation of the zygote

Question 17

What occurs during implantation?

Answer 17

Tropholast erodes uterine wall

Question 18

Three Primary Germ Layers

Answer 18

Ectoderm
Endoderm
Mesoderm

Question 19

The ectoderm and endoderm form what?

Answer 19

Sheets of epithelial tissue

Question 20

The mesoderm forms what?

Answer 20

Mesenchyme tissue

Question 21

Define Gastrulation

Answer 21

Invagination of epiblast cells

Question 22

When does the endoderm form?

Answer 22

Days 14-15

Question 23

When does the mesoderm form?

Answer 23

Day 16

Question 24

What occurs during days 16-18?

Answer 24

Epiblast cells invaginate
Migrate anteriorly with endoderm cells
Rod defining body axis formed
Notochord is future site of vertebral column

Question 25

Define Neurulation

Answer 25

Formation begins of spinal cord and brain

Question 26

What occurs during neurulation

Answer 26

Neural plate to neural groove to neural tube

Question 27

What are the three regions of the mesoderm?

Answer 27

Somites: beginning of vertebral bones Intermediate mesoderm Lateral plate: forms cavity

Question 28

When does the neural tube close?

Answer 28

Starts at the end of week 3 and completes at end of week form

Question 29

What is the somatic mesoderm opposed to?

Answer 29

Ectoderm

Question 30

What is the splanchnic mesoderm opposed to?

Answer 30

Endoderm

Question 31

What is between the somatic mesoderm and splanchnic mesoderm?

Answer 31

Coelom

Question 32

What serous cavities form from the coelom?

Answer 32

Peritoneal Pericardial Pleural

Question 33

Major Derivatives of the Ectoderm

Answer 33

Epidermis, hair, nails, glands of skin Brain & spinal cord Neural crest: sensory nerve cells, nervous structures, pigment cells, portions of skeleton, blood vessels in H&N

Question 34

Major Derivatives of the Endoderm

Answer 34

Epithelial lining and glands of digestive and respiratory tracts

Question 35

Major Derivatives of the Mesoderm

Answer 35

``` Nucleus pulposus Vertebrae & ribs Dermatomes Trunk & limb musculature Kidneys Gonads Parietal serosa Ventral body dermis CT of limbs Wall of digestive & respiratory tracts Visceral serosa Heart Blood vessels ```

Question 36

When does the heart start pumping?

Answer 36

4 weeks to 1 month

Question 37

When Does Organogenesis Occur?

Answer 37

Weeks 3-8

Question 38

What occurs during organogenesis?

Answer 38

Stem cell populations established for each organ | MOST gross structural birth defects are induced

Question 39

What is the significance of organogenesis?

Answer 39

Mother MUST avoid environmental, dietary, and drug exposure during this period