Embryonic Period

Question 1

What happens during the embryonic period (stage)?

Answer 1

1. blastocyst to embryo
2. cytodifferentiation
3. growths
4. differentiation
5. bilaminar embryonic disc
6. trophoblastic layer

Question 2

blastocyst becomes to embryo around what time frame?

Answer 2

from second to eighth week

Question 3

differentiation occurs at various rates in the embryo. define cytodifferentiation

Answer 3

the development of different cell types

Question 4

cytodifferentiation has receptors and processes. What are the receptors of the cytodifferentiation?

Answer 4

1. none present
2. couple receptors
3. more receptors
4. still more receptors

Question 5

describe each receptors

Answer 5

1. none present = cells die (cell death)
2. couple receptors = cells survive
3. more receptors = cells proliferate (come to life)
4. still more receptors = cells differentiate (into different kinds of cells)

Question 6

what are the two processes of the cytodifferntiation?

Answer 6

1. autocrine process

2. paracrine process

Question 7

what is meant by autocrine?

Answer 7

cell receives hormone or receptor stimulation from substances produce by itself

Question 8

what is meant by paracrine process?

Answer 8

cell receives hormone or receptor stimulation from a substance produced by a different cell

Question 9

receptor is also called?

Answer 9

hormone

Question 10

what are the types of growth during the embryonic period?

Answer 10

1. aptosis
2. induction
3. proliferation
4. interstitial
5. appositional

Question 11

define each growth

Answer 11

1. aptosis=programmed cell death (e.g. your webbed hand become fingers)
2. induction=one group of cells starting the development of another cellular group
3. proliferation=more cells
4. interstitial = occurs deep within a tissue
5. appositional=additional “outer” layer of cells

Question 12

what are the differentiation types in the embryonic period

Answer 12

1. histodifferentiation
2. morphodifferentiation
3. morphogenesis
4. maturation

Question 13

what is the definition of histodifferentiation?

Answer 13

development of different tissues within a structure

Question 14

what is the definition of morphodifferentiation?

Answer 14

development of different forms (structure or shape)

Question 15

what is the definition of morphogenesis?

Answer 15

process where tissues evolve into more complex structures or shapes
(the process of development of SPECIFIC tissue structure or shape; e.g. enamel)

Question 16

what is the definition of maturation?

Answer 16

ongoing physiological processes which imparts the FINAL form/function

Question 17

in the second week of embryonic period a _____ ______ ______ is developed from the blastocyst and appears as a flattened, essentially circular plate of bilayered cells

Answer 17

bilaminar embryonic disc

Question 18

the bilaminar disc is suspended in the uterus’s endometrim b/w two fluid-filled cavities. Name them

Answer 18

1. amniotic cavity

2. yolk sac

Question 19

the amniotic cavity is fluid filled and faces what layer?

Answer 19

the epiblast layer

Question 20

the yolk sac is fluid filled and faces what layer?

Answer 20

the hypoblast layer

Question 21

the yolk sac also serves as what for the embryonic disc?

Answer 21

serves as initial nourishment for the embryonic disc until the placenta is established

Question 22

the bilaminar embryonic disc has both a superior and inferior layer. What are they?

Answer 22

1. epiblast layer, which is the superior layer

2. hypoblast layer, which is the inferior layer

Question 23

the epiblast, hypblast, amniotic cavity and the yolk sac are surrounded by what layer?

Answer 23

surrounded by the trophoblastic layer

Question 24

what is special about the trophoblast layer?

Answer 24

the trophoblast layer helps the bilaminar disc to embed in the uterine wall

Question 25

the third week in the embryonic period another cell is created. how and what is the name?

Answer 25

some cells from the epiblast layer move or migrate toward the hypoblast layer only in the area of the primitive streak. these migratory cells locate in the middle b/w the epiblast and hypoblast layers and become MESENCHYMAL CELLS, an embryonic connective tissue

Question 26

with three layers present, the bilaminar disc has become thickened into what kind of disc?

Answer 26

a trilaminar embryonic disc, thus the trilaminar disc has three embryonic cell layers.

Question 27

with the creation of this new embryonic cell layer of mesoderm, what happens?

Answer 27

the epiblast layer is now ectoderm | the hypoblast layer is now endoderm

Question 28

What are the three embryonic cell layers?

Answer 28

ectoderm mesenchymal hypoblast

Question 29

during the beginning of the third week of prenatal development within the embryonic period what is formed within the bilaminar disc?

Answer 29

the primitive streak is formed

Question 30

describe the primitive streak

Answer 30

furrowed, rod-shaped thickening in the middle of the disc

Question 31

the primitive streak is a result of what?

Answer 31

from an increased proliferation of cells in the midline area

Question 32

the primitive streak causes the disc to have bilateral symmetry, with a....

Answer 32

right half and left half

Question 33

mesenchymel is also called and inter changeable with?

Answer 33

mesoderm

Question 34

in addition, during the third week, another specialized group of cells are developed. what are they?

Answer 34

the neural crest cells

Question 35

the neural crest cells arise from what?

Answer 35

arise from proliferation of ectoderm adjacent to primitive streak

Question 36

the primitive streak matures into ____ which supports the ____ ______?

Answer 36

notochord; primitive embryo

Question 37

the neural crest cells are responsible for what structures?

Answer 37

the head and neck structures

Question 38

each embryonic cell layer is distinct from the others. how?

Answer 38

embryonic cell layer gives rise to specific tissue

Question 39

What does the ectoderm give rise to?

Answer 39

skin, CNS and PNS, hair, nails, ENAMEL, and lining of the oral cavity

Question 40

what does the mesoderm give rise to?

Answer 40

bone, muscles, circulatory and reproductive system, internal organs, DENTIN, PULP and CEMENTUM

Question 41

what does the endoderm give rise to?

Answer 41

lining of respiratory passage, glandular organs and digestive

Question 42

which cell layer gives the smallest contribution?

Answer 42

endoderm cell layer

Question 43

which cell layer gives the largest contribution?

Answer 43

mesoderm cell layer

Question 44

what should we remember about the mesoderm cell layer

Answer 44

the mesoderm cell layer arose from ECTODERM