Embryo Basics

Question 1

What weeks make up the embryonic period? and what is the main function of it?

Answer 1

weeks 3-8 and organogenesis

Question 2

what weeks make up the fetal period and what goes on?

Answer 2

weeks 9-38

growth and development

Question 3

what type of stem cells start development?

Answer 3

pluripotent cells

Question 4

of congenital abnormalities, what percent do teratogens cause?

Answer 4

7-10 percent

Question 5

define birth defect

Answer 5

abnormality present at birth

Question 6

define malformation

Answer 6

developmental structure abnormality from intrinsic factor

Question 7

define deformation

Answer 7

development structure abnormality from extrinsic factor

Question 8

what can happen during the embryonic period?

Answer 8

this period is most sensitive to teratogens and since its the start of organ dveelopment if something goes wrong it can cause a major anomaly

Question 9

what can happen during fetal period?

Answer 9

not as sensitive to teratogens…will lead to minor anomalies since there are more normal cells already present

Question 10

name three things the placenta functions as in utero

Answer 10

lungs kidneys and Gi tract

Question 11

week one development steps

Answer 11

fertilization to zygote to morula to blastocyst then implantation

Question 12

what are the two parts of the blastocyst?

Answer 12

inner cell mass and trophoblast

Question 13

what does the inner cell mass become?

Answer 13

embryo

Question 14

what does the trophoblast become?

Answer 14

placenta

Question 15

what four things form in week 2?

Answer 15

epiblast, hypoblast and amniotic cavity and primitive streak

Question 16

what happens to the epiblast and hypoblast?

Answer 16

epiblast becomes embryo and hypoblast dies off

Question 17

what is the primitive streak that develops in week 2?

Answer 17

this is the midline

Question 18

what three things develop in week 3?

Answer 18

ectoderm, mesoderm, endoderm

somites

nervous system

Question 19

what is the formation of the three germ layers called in week 3?

Answer 19

gastrulation

Question 20

explain gastrulation process

Answer 20

cells from the spiblast migrate and become the ecto and mesoderm…then epiblast becomes the ectoderm

Question 21

what does the ectoderm lead to?

Answer 21

skin, teeth and CNS

Question 22

what does the mesoderm lead to?

Answer 22

muscle, bone, connective tissue, blood and vessels, deep layers of skin

Question 23

what does the endoderm lead to?

Answer 23

epithelial lining of respiratory and GI tracts

Question 24

which of the three layers do somites arise from?

Answer 24

mesoderm

Question 25

how many somite pairs are there?

Answer 25

35-37

Question 26

what three things does a somite divide into?

Answer 26

scleratome, myatome and dermatome

Question 27

what is the dermatome of a somite?

Answer 27

skin

Question 28

what is the scleratome of a somite?

Answer 28

bone

Question 29

what is the myatome of a somite?

Answer 29

muscle

Question 30

what happens in week 4?

Answer 30

organogenesis…folding longitudinal and transverse

Question 31

what results from longitudinal folding in week 4?

Answer 31

heart moves from cranial position toward the thoracic trunk

Question 32

what results from the transverse folding in week 4?

Answer 32

transvers folds bilaterally come together to meet ventrally and make the thorax, pelvis and abdomen and body cavities, and GI tract

Question 33

what happens in weeks 5-8?

Answer 33

more organ development…by week 8 most all organs are present for normal life and you look like a human