Embryology

Question 1

embryology

Answer 1

developmental events that occur prior to birth

Question 2

cell differentiation

Answer 2

transformation into specific cell types

Question 3

cell development

Answer 3

process by which cells become fully functional (maturation)

Question 4

prenatal period

Answer 4

first 38 weeks of human development

Question 5

three developmental stages

Answer 5

1. pre-embryonic period
2. embryonic period
3. fetal period

Question 6

1. pre-embryonic period

Answer 6

-first two weeks after fertilization of egg
-formation of blastocyst
-ends with implantation in lining of uterus

Question 7

2. embryonic period

Answer 7

-3rd through 8th weeks
-all major organ systems begin to develop

Question 8

3. fetal period

Answer 8

-9th through 38th weeks (birth)
-growth and development continues
-ends at birth

Question 9

what are the mitotic divisions of a zygote called

Answer 9

cleavage

Question 10

zygote

Answer 10

fertilized egg

Question 11

once the zygote reaches the 16-cell stage, what is it called?

Answer 11

morula

Question 12

after the morula enters the uterine cavity, what does it become?

Answer 12

blastocyst

Question 13

2 components of blastocyst

Answer 13

trophoblast and embryoblast

Question 14

trophoblast

Answer 14

outer ring of cells that will develop into the chorion (placenta)

Question 15

embryoblast

Answer 15

cluster of tightly packed cells inside the blastocyst that will form the embryo

Question 16

pluripotent

Answer 16

can differentiate into any cell type in the human body

Question 17

how long until the blastocyst enters the uterus?

Answer 17

one week

Question 18

what layer does the blastocyst enter first

Answer 18

endometrium (lining of uterus)

Question 19

by day 9, what has the blastocyst done?

Answer 19

completely burrowed into the uterine wall

Question 20

By day 8, cells of the embryoblast differentiate into two distinct types:

Answer 20

1. hypoblast
2. epiblast

Question 21

hypoblast

Answer 21

layer of small cuboidal cells facing the blastocyst cavity

Question 22

epiblast

Answer 22

layer of columnar cells deep to the hypoblast

Question 23

together, the two layers of the embryoblast form a flat disc called the

Answer 23

bilaminar germinal/embryonic disc

Question 24

Extraembryonic membranes

Answer 24

1. Yolk sac
2. Amnion
3. Chorion

Question 25

Yolk sac

Answer 25

Serves as a site for early blood cell and vessel formation (attached to hypoblast); where blood cells initially develop

Question 26

Amnion

Answer 26

Thin layer of cells that forms above and is derived from the epiblast

Question 27

Amniotic cavity

Answer 27

Fluid filled cavity that appears between the amnion and epiblast layer

Question 28

Chorion

Answer 28

Outermost membrane responsible for formation of the placenta

Question 29

Placenta

Answer 29

Highly vascularized organ that serves as an interface between embryo or fetus and mother

Question 30

Embryonic portion of the placenta is the...

Answer 30

chorion

Question 31

Functions of placenta

Answer 31

-Exchange of nutrient between embryo and mother -production of estrogen and progesterone to maintain uterine lining

Question 32

What does the embryonic period start

Answer 32

Establishment of 3 primary germ layers

Question 33

Gastrulation

Answer 33

Process by which cells from the epiblast migrate to form the primary germ layers (week 3); becomes 3 layered structure

Question 34

Gastrulation starts with

Answer 34

Formation of the primitive streak

Question 35

Primitive node

Answer 35

Cephalic end of the primitive streak

Question 36

Primitive pit

Answer 36

Depression in primitive node

Question 37

Three primary germ layers

Answer 37

-endoderm -ectoderm -mesoderm

Question 38

Structure is called an embryo when

Answer 38

Three primary germ layers are present

Question 39

Invagination

Answer 39

Inward movement of cells from epiblast layer through primitive streak between epiblast and hypoblast layers

Question 40

Epiblast turns into...

Answer 40

ectoderm

Question 41

Other migrating cells displace the hypoblast and become the

Answer 41

Endoderm

Question 42

All three germ layers are derived from the

Answer 42

Epiblast

Question 43

Formation of the neural tube begins with the appearance of the

Answer 43

Notocord

Question 44

Notocord

Answer 44

-derived from mesoderm -important signaling structure

Question 45

Neurulation

Answer 45

The formation of the neural tube from overlying ectoderm cells

Question 46

The neural tube will develop into the

Answer 46

Central nervous system

Question 47

Cehalocaudal folding

Answer 47

Head and tail folding

Question 48

Transverse folding

Answer 48

Lateral folding

Question 49

Teratogens

Answer 49

Any agents that can cause congenital malformations (birth defects)

Question 50

Ectoderm consists of

Answer 50

Covering and lining; skin

Question 51

Mesoderm becomes

Answer 51

Bones and muscles

Question 52

Endoderm becomes

Answer 52

Innermost linings; digestive tract, bladder, liver, etc

Question 53

Organogenesis:

Answer 53

Organ development -rudimentary forms of most organ systems are complete by the end of the embryonic period (week 8)