Second Third Week Flashcards
1
Q
what does epiplast forms
A
amniotic cells & amniotic caity
2
Q
embroblast forms what
A
epiblast & hypoblast
3
Q
what is another name for trophoblast
A
outer cell mass
4
Q
what does trophoblast form
A
fetal side of placenta
5
Q
why do we have little lacunae that occur on the syncytiotrophoblast
A
ultimately nutrients go into epiblast
6
Q
what does hypoblast cells do
A
line the inner lining of yolk sac
transdifferentiate
7
Q
what is transdifferentiate
A
change entire cell property
8
Q
hypoblasts do what regarding migration?
A
migrate out and form very thick band of extra embrionic mesoderm
9
Q
what does extra embrionic mesodierm form
A
fetal side of placenta
10
Q
once fetal side of placenta forms what happens
A
little holes form
11
Q
what happens if lots of holes are formed in extraembryonic mesoderm
A
it splits into two parts: visceral and parietal
12
Q
when all the lacune merge together what do they form
A
one chorionic cavity
13
Q
what is the outer cavity of yolk sac called
A
extraembryonic visceral mesoderm
14
Q
what forms half of the connecting stalk and also coats yolk sac
A
extraembryonic visceral mesoderm
15
Q
what forms the connecting stalk
A
1/2 from visceral and 1/2 from parietal mesoderm
16
Q
what eventually happens to the visceral and parietal mesoderm
A
it will go away
17
Q
in week two what disappears
A
primary yolk sac
18
Q
when does yolk sac decrease
A
week 14-20
19
Q
why does yolk sac decrease
A
europlacental circulation takes over
20
Q
what does embryonic parietal mesoderm help form
A
secondary chorionic villi
21
Q
what happens if blastocyst dies but trophoblast does not
A
trophoblast pumps out more hhg and can potentially give rise to cancer
22
Q
what 3 major things happen in week 3
A
primitive streak - definitive
notochord
gastrulation - 3 layers
23
Q
what happens in primitive streak
A
where primoridal germ cells go through during development of gametes
24
Q
where is primtiive streak located
A
in the back of embryo
25
where is epiblast layer
on front part
26
what does notochord do
it doesnt form anything but tells other things what to do
27
what is gastrulation
differentiation of three germ layers
28
what 3 germ layers develop (3 layers of trilaminar disk)
intraembryonic ectoderm
intraembryonic mesoderm
extraembryonic endoderm
29
what is the first sign of gastulation
primitive streak
30
what does the first population of cells help to form
intraembroyinic endoderm
31
what does the second population of cells help to form
intraembryonic mesoderm
32
what forms the floor
the endoderm
33
what goes in like water and fills up the middle
intraembroyinic mesoderm
34
what do the third population of cells form
pinched off to form neurotube
35
what is notocord formed from
mesendermal cells
36
what does notocord do
tells the overlying ectoderm to form the neuroectoderm
37
what happens to neuroectoderm
pinches off to form neurotube
38
what does neurotube form
central and peripheral nervous system
39
what cells dont migrate ad what do they form (fourth population of cells)
ectoderm
40
what is the function of allantois
involved in fetal excretion
41
what takes over the allantois
placenta
42
what is the tailfold and what does it do
allantosis shoved into connected stalk - the vessels of alantosis (arteries and veins) migrate from allantosis and goes into connecting stalk and forms the umbilical vessels
43
before neuro tube closes what are the cells around it called
neural crest cells
44
what is the function of neural crest cells
```
peripheral nervous system
dorsal root ganglia
skeletal and musclar parts
meningeal coveraings
melanocytes in epidermis of skin and hair
```
45
where do neural crest cells go
migrate to target organs
46
what causes hypoblast cells to remodel the primitive yolk sac
endoderm cells coming in and pushing them out
47
what lines the yolk sac
endoderm
48
what forms the epithelial lining of gut tube
endoderm
49
what does endoderm do
forms gut tube & endoethelial lining of all GI tract ecept mouth and distal and anus and lining of respiratory tract, and anything that buds off of GI tract (baldder, lungs)
50
If it buds off of GI tract, what does it come from
endoderm
51
paraxial mesoderm ahs what two parts
sclerotome
| dermomyotome
52
what does sclerotome form
axial skeleton (torso)& neurocranium
53
what is visceral cranium formed from
neural crest cells
54
what does dermomyotome form
dermis of skin of the back
| skeletal muscle of torso and limbs
55
the skin is formed from ectoderm only - yes or no?
no - outer lining of epitherlium but dermis of skin is formed from dermomyotome
56
what forms all the skeletal muscles
dermomyotome
57
urinary system is only formed from what
intermediate mesoderm
58
the lateral plate mosoderm is split into what two parts
visceral lateral plate mesoderm
| parietal lateral plate mesoderm
59
what forms cardiovascular system
visceral lateral plate mesoderm
60
what does ectoderm help form
top layer - epithelial lining
61
where does heart move to
from the dorsal side of embryo to
62
what does lateral fold pinch off
the yolk sac
63
where doesnt the lateral fold pinch off
connecting stalk
64
what does lateral fold pinch off
ventral part of developing embryo except connecting stalk
65
where does the lateral fold pinch off
vitilointestinal duct
66
what happens if lateral fold doesnt pinch off
mekel's diverticulum
67
what is hydraminios/polyhydramios
too much amniotic fluid
68
what is oligohydramios
too little amniotic fluid
69
what is the most common cause of hydramnios
idiopathic (we dont know why)
70
how can esophageal atresia cause hydramnios
normally baby drinks some amniotic fluid, if esophagus ends, baby drinks it and then it vomits it out, when baby drinks amniot fluid normally baby keeps 1/3 of fluid, if baby throws up fluid and isn't retaining any then will have too much amniotic fluid
71
how can esophageal atresia cause hydramnios
normally baby drinks some amniotic fluid, if esophagus ends, baby drinks it and then it vomits it out, when baby drinks amniot fluid normally baby keeps 1/3 of fluid, if baby throws up fluid and isn't retaining any then will have too much amniotic fluid
72
what are main causes of oligohydramnio
renal agenesis
amnion rupture due to trauma
urinary obstructive lesions
73
what is pulmonary hypoplasia
incomplete development of lungs
74
what can cause pulmonary hypoplasia
oligohydramnio
75
fetal side of placenta is called what
chorion
76
why are villi important
effecient gas exchange, want water and gas in and waste out
77
what are the three types of chorionic villi
primary
secondary
tertiary
78
as pregnancy continues what villi increase and decrease
primary amount goes down
| secondary and tertiary goes up
79
What is the name of the fetal side of the placenta
chorion/chorionic plate
80
what makes up the fetal side of the placenta
Chorion= trophoblast layers ((Syncytiotrophoblast (*), Cytotrophophoblasts(**)) and parietal extraembryonic mesoderm
81
what makes up the maternal side of the placenta
cotyledon - little bumps
| decidua
82
what is major difference b/w tertiary and secondary
tertiary has everything secondary does plus capillary
83
what happens in fetal period 9-40th week
mainly growth and maturation of tissues, addition of fat
84
what is different in 11 to 31 weeks
large deposition of fat
85
when are most organ systems established and functioning
by end of 8th week
86
two kinds of multiple pregnancies:
dizygotic/fraternal twins
| monozygotic/maternal/identical twins
87
what is another name for identical twins
monozygotic
88
what is another name for fraternal twins
dizygotic
89
how do fraternal twins occur
two fertilized zygotes - 2 ovuum are ovulated) have two chorionic sacs, two amnions, two placents, may not be same sex and different morphology
90
how do identical twins occur
originate from one zygote and are the same sex, genetically identical and very similar in physical appearance
91
what is chromosome number in blasphomeres
46, 2N
92
how many chorionic sacs are there in dizygotic twins
2
93
how many placentas are in dizygotic twins
2
94
what are the three locations monozygotic twins can occur
separation at blastula containing two blastomeres stage
separation at early blastocyst stage
separation at bilaminar germ disc stage
95
describe what happens if there is separation at blastula containing two blastomeres
similar to dizygotic twins (2 placenta, etc) but genetic makeup, fingerpreints, sex are similar
96
morula becomes what
blastocyst
97
describe what happens when there is separation at early blastocyst stage
inner cell mass splits into two separate groups withint he same blastocyst, two blastocyst have a common placenta, commoon chorionic cavity but separate amnionic sacs
98
describe what happens at bilaminar germ disc stage to have monozygotic twins
two blastocysts have a single placenta and common chorionic and amnioic cavities
99
how many placentas are present if separation atbilmaniar germ disc occurs and produces monozygotic twins
1
100
how many placenta are there if there is separation at early blastocyst for monozygotic twins
1
101
Which of the following is most likely about embryonic folding?
A. Head fold forces the heart to the dorsal surface
B. Head fold forms the midgut only
C. Laterl fold enlargs the yolk sac
D. Tail fold helps to form primary villi
E. All 3 folds pinch off yolk sac
E
102
What does head fold form
foregut
103
what does tailgut form
hindgut
104
what does lateral fold form
midgut
105
does the tail fold help to form primary villi
no
106
do all 3 fold pinch off yolk sac?
yes
107
what is clinical corrilation if the 3 folds do not pinch off correctly
meckel's diverticulum
108
Which of the following is most likely about villi
A: formed from hypoblst cells only
b. primary villi contain only cytotrophoblst cells
c. secondar villi contain synctiotrophoblast and cytotrophoblast cells only
d. tertiary villi contain all the components of secondary villi plus placental barrier
e. tertiary villi decrease in number as pregnancy continues
D
109
Are villi formed from hypoblast ells only
no
110
do primary villi contain only cytotrophoblast cells?
no
111
Where the epiblast and hypoblast fused, what is it called?
prechordal plate
112
what is the significance of the prechordal plate?
helps establish rostral-caudal orientation (front and back of baby)
113
what is a hydatiform mole?
what cancer is called if there is no embryo but still a trophoblast
114
Third epiblast form what?
neuroectoderm
115
Fourth epiblast form what?
intraembryonic ectoderm
