Bilaminar and Trilaminar embryonic disks Flashcards Preview

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Flashcards in Bilaminar and Trilaminar embryonic disks Deck (29):
1

inner cell mass

embryoblast

2

outer cell mass

trophoblast
two layers: cytotrophoblast-mitotic figures
syncitiotrophoblast

3

syncitiotrophoblast

1. secretes hCG 2. used in implantation (chews into the endometrium)

4

decidual reaction

uterus realizes that embryo has implanted so it sends nutrients to the egg to help it grow and develop

5

embryoblast fate

becomes epiblast (which becomes everything else, including amnioblasts)
hypoblast
separated by basement membrane

6

epiblast

pluripotent cell that forms many embryonic cells, such as amnioblasts which form the amniotic cavity and secrete amniotic fluid

7

fibrin plug

completes the implantation of the embryo into the endometrium (day 10)

8

lacunae

hypoblast cells begin to multiply and extracellular vacuoles appear in syncitiotroph and join to make the lacunae (blood lake)

9

genetic imprinting experiments

male csome: regulate embryoblast
femal csome: regulate trophoblast

10

fate of blastocystic cavity

lined with hypoblast and converts it to the primary yolk sac (first site of hematopoesis)

11

levels of hCG

double every two days
used to follow normal pregnancy
used to test for pregnancy

12

chorionic cavity formation

need migration of epiblasts to the extra embryonic mesoderm

forms between yolk sac and cytotrophoblast

13

primary yolk sac

hypoblast migration transforms blastocyst into primary yolk sac

14

extraembryonic mesoderm laeyers

splanchic mesoderm surrounds yolk sac
somatic mesoderm:
-lines the cytotrophoblast
-becomes the connecting stalk (umbilicus)
(2 weeks)

15

chorion components

syncitiotrophoblast
cytotrophoblast
extraembryonic mesoderm
(2 weeks)

16

secondary yolk sac

responsible for hematopoiesis and primordial cell growth
(2 weeks)

17

early placenta

utero-placental circulation by the maternal blood lacunae in endometrium and invasion of ST+chorionic villi

18

Week of 2s

2 trophoblastic layers - cytotrophoblast and
syncytiotrophoblast
2 layers from the inner mass - epiblast and hypoblast
2 yolk sacs - primary and secondary
-2 extraembryonic mesoderms - splanchnic and somatic
-2 future cavities - chorionic and amniotic
-2 components of the placenta - endometrium and chorion
-2 clinical uses of beta hCG

19

primitive streak

3rd week
has node, pit and groove
establishes position and polarity
dorsal-ventral, right-left, cranial-caudal

20

buccopharyngeal membrane and cloacal membrane

where epiblast and hypoblast are fused in primitive streak

21

gastrulation

movement of epiblast cells toward the primitive groove

form definitive endoderm and intraembryonic mesoderm

epiblast cells proliferate and lose adhesions, grow pseudopodia and move toward primitive streak

22

three layers gastrulation forms

definitive endoderm
intraembryonic mesoderm
trilaminar embryo
all layers derived from epiblast

23

sacrococcygeal tumor

result of a primitive streak that does not disappear after the 4th week, most common tumor in newborns

24

fate mapping

the destiny of the epiblast cells depend on what part of the embryo they come from
differentiation of the mesoderm begins cranially and proceeds caudally

25

mesoderm derivatives

1. axial mesoderm
2. paraxial mesoderm
3. intermediate mesoderm
4. lateral plate mesoderm
5. mesodermal contribution to the chorion

formation of notochord and neurulation finish in 3rd week

26

notochord formation

3rd week, from axial mesoderm
formation is a series of steps involving fusing with
the endoderm

-defines primary axis, gives embryo some rigidity
-induces formation of vertebral column
-induces neuroectoderm to form neural plate
-persists as the nucleus pulposus in the
intervertebral disc until early childhood. Likely
replaced by connective tissue

27

prechordal plate (endoderm)

sets the limit of rote cranial migration of the notochordal cells
induction of the forebrain

28

neurulation

prechordal plate and notochord induce neural plate formation in the overlying ectoderm
neural plate differentiates to neuroectoderm that forms brain and spinal cord during embryonic period

29

week of threes

-3 parts to the primitive streak - groove, pit, node
-3 directions imparted by the primitive streak:
dorsal-ventral
right-left
cranial-caudal
-3 definitive germ layers - ectoderm, mesoderm, endoderm
-3 types of villi - primary, secondary, tertiary