Bilaminar and Trilaminar embryonic disks

Question 1

inner cell mass

Answer 1

embryoblast

Question 2

outer cell mass

Answer 2

trophoblast
two layers: cytotrophoblast-mitotic figures
syncitiotrophoblast

Question 3

syncitiotrophoblast

Answer 3

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

Question 4

decidual reaction

Answer 4

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

Question 5

embryoblast fate

Answer 5

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

Question 6

epiblast

Answer 6

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

Question 7

fibrin plug

Answer 7

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

Question 8

lacunae

Answer 8

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

Question 9

genetic imprinting experiments

Answer 9

male csome: regulate embryoblast

femal csome: regulate trophoblast

Question 10

fate of blastocystic cavity

Answer 10

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

Question 11

levels of hCG

Answer 11

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

Question 12

chorionic cavity formation

Answer 12

need migration of epiblasts to the extra embryonic mesoderm

forms between yolk sac and cytotrophoblast

Question 13

primary yolk sac

Answer 13

hypoblast migration transforms blastocyst into primary yolk sac

Question 14

extraembryonic mesoderm laeyers

Answer 14

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

Question 15

chorion components

Answer 15

syncitiotrophoblast
cytotrophoblast
extraembryonic mesoderm
(2 weeks)

Question 16

secondary yolk sac

Answer 16

responsible for hematopoiesis and primordial cell growth

2 weeks

Question 17

early placenta

Answer 17

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

Question 18

Week of 2s

Answer 18

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

Question 19

primitive streak

Answer 19

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

Question 20

buccopharyngeal membrane and cloacal membrane

Answer 20

where epiblast and hypoblast are fused in primitive streak

Question 21

gastrulation

Answer 21

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

Question 22

three layers gastrulation forms

Answer 22

definitive endoderm
intraembryonic mesoderm
trilaminar embryo
all layers derived from epiblast

Question 23

sacrococcygeal tumor

Answer 23

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

Question 24

fate mapping

Answer 24

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

Question 25

mesoderm derivatives

Answer 25

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

Question 26

notochord formation

Answer 26

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

Question 27

prechordal plate (endoderm)

Answer 27

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

Question 28

neurulation

Answer 28

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

Question 29

week of threes

Answer 29

-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