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Flashcards in The third week Deck (32):
1

what does the third week represent in the development of the human ?

gasturlation, formation of the three layers and organs

2

at the end of the second week what happens to the embryonic disk ?

becomes elongated and is broader at the butt end (cephalic end)

3

What happens on day 15

epiblast cells begin to migrate towards the midline forming a groove

4

the primitive pit develops into what

notochord

5

What is the notochord composed of ?

mesoderm and endodermal cells

6

What are the four functions of the notochord ?

CNS development, development of the vertebral column, anatomic midline, and forms the nucleus pulposis

7

ectopodiacordis

heart is outside of the body

8

what contributes to the longitudinal (head tail fold)

occurs along the saggital plane and is due to the rapid growth of the CNS and differential growth

9

What roles do the primitive streak and the primitive node play in development ?

determination of the body axes

10

dextrocardia

heart is on the wrong side of the body

11

what induces the epiblast to proliferate and migrate towards the midline forming a groove ?

hypoblast cells

12

day 16

epiblast cells proliferate and migrate through the primitive streak into the space between the epiblast and the hypoblast

13

when cells completely display the hypoblast cells so that thehypoblast is completely repopulatioed this is defined as what ?

endoderm

14

epiblast cells begin to occupy the space between the endoderm and the epiblast

intraembryonic mesoderm

15

epiblast that do NOT migrate through the streak are known as

ectoderm

16

cells from the primitive pit invaginate and create a hollow tube what is this called

notochord

17

floor of notochorrdal processes fuse with endoderm and form

notochordal plate

18

notochordal plate detaches beginning at the cranial end to form/

notochord

19

where does the notochord extend from ?

prechordal plate to primitive pit

20

what is the neurenteric canal

connection between the amniotic cavity and the yolk sac

21

neurenteric cysts

masses of endodermally derived tissue commonly associated with spinal cord derived from neurenteric canal where ectoderm and endoderm are closely associated

22

at the buccopharyngeal membrane what begins to forms in the 3rd week

mouth

23

at the cloacal membrane what begins to form in the 3rd week

anus

24

what is the major outcome of the longitudinal fold

elongated gut tube and closure of the body cavity

25

situs inversus

complete-all organs are mirror image of normal orientation; incomplete-only a single organ is involved

26

sirenomelia

caudal dysgenesis resulting from inadequate mesoderm in caudal regions (limb and urogenitcal defects)

27

sacrococcygeal teratoma

results from persistence of the primitive streak and pluripotent cells

28

during the first week of the embryonic period how is the age determined

by the number of somites

29

after week four how is the age of the embryo expressed

crown rump length (vertex of skull to caudal tip of the trunk)

30

sacrococcygeal teratoma

persistence of the primitie streak and pluripotent cells

31

dextrocardia

heart is on the wrong side of the body

32

ectopia cordis

heart outside of the body