Chapter 12 mammals Flashcards

1
Q

Mammalian development leads to _______ cleavage

A

rotational

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2
Q

The first division in mammals is _______ while the second cleavage is ______

A

meridional
asymmetrical
- one is meridional while the other is equitorial

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3
Q

In mammalian cleavage, loosely connected cells of the blastula “huddle” together in a process called _______

A

compaction

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4
Q

Expression of _______ causes compacting cells to form a compact ball of cells (what allows compaction?)

A

E-cadherins

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5
Q

Compacting cells are stabilized by _______ junctions

A

tight
- seals off the inside of the mass from the outside

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6
Q

Compacting cells form _______ junctions, allowing communication via small molecules

A

gap

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7
Q

The Morula (_____ cell stage), is where the first real differentiation event, and is composed of what 2 parts?

A

Inner cell mass (ICM, epiblast)
- pluripotent, becomes embryo
Trophectoderm (trophoblast)
- becomes chorion

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8
Q

In the beginning of trophoblast, ICM determination, all cells express _______

A

Cdx2

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9
Q

Trophoblast ICM determination:
Trophoblast cells continue to express Cdx2 as activated by _______

A

Yap

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10
Q

Trophoblast ICM determination:
In trophoblast cells, Yap binds to _______ as a cofactor required for Cdx2 transcription

A

Tead4

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11
Q

Trophoblast ICM determination:
ICM receive the _______ signal that activates the _______ kinase

A

Hippo
lats

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12
Q

Trophoblast ICM determination:
Lats phosphorylates and inactivates _______ so that it cannot induce the Cdx2 expression

A

Yap

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13
Q

Describe the process of determining trophoblast cells?

A

1) Yap binds to Tead4
2) Cdx2 is transcribed blocking Oct4
3) lack of surrounding cells leads to a blockage of the HIPPO signal so that Lats is not activated
- how it differentiates from ICM
- ultimately Cdx2 expression determines (cuz Oct4)

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14
Q

_______ is created by trophoblast cells secreting fluid into the morula, creating space

A

blastocoel

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15
Q

the process of creating blastocoel by trophoblast cells secreting fluid into the morula is called _______

A

cavitation

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16
Q

Cavitation requires the action of _______ and _______ pumps to increase ion concentration outside of trophoblast cells

A

Na+/H+ antiporter
Na+/K+ ATPase
- both pump Na+ out of trophoblast cells

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17
Q

The _______ remains in place during the embryo’s journey through the oviducts towards the uterus

A

zona pellucida
- prevents premature implantation in the walls of the fallopian tubes

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18
Q

Once in the uterus, the blastocyst hatches free from the zona pellucida by digesting a small hole with a _______ and squeezing through

A

trypsin-like protease

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19
Q

_______: implantation in any location other than the endometrial lining of the uterus

A

ectopic pregnancy
- also called tubal pregnancy
- can kill the mother via hemorrhaging

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20
Q

The blastocyst caught by _______ of trophoblast cells binding to endometrial sulfated polysaccharides

A

L-selectin

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21
Q

After binding of L-selectin and endometrial sulfated polysaccharides, secondary binding of _______ and _______ “dock” the embryo into the uterus

A

integrins and P-cadherins

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22
Q

Once bound to the endometrium, the embryo then secretes several proteases that allow it to burrow into the lining of the uterus. A process called _______

A

implantation

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23
Q

Implantation is mediated by signals involving _______ protein signals

A

Wnt

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24
Q

What are the 3 enzymes that digest the ECM of the uterine tissue?

A

1) Collagenases
2) Stromelysin
3) Plasminogen activator

25
Q

Since mammals don’t have a large yolk, a _______ must be established with the mother to exchange nutrients

26
Q

What are the 2 parts of the placenta?

A

1) Chorion
- from trophoblast, Fetal portion
2) Decidua
- from uterine lining, maternal portion

27
Q

The decidua is formed from uterine lining cells induced by signals from the _______

28
Q

The inner cell mass cells divide into the _______

A

bilayer germinal blastodisk
- will delaminate to form epiblast and hypoblast

29
Q

Hypoblast will delaminate to line the blastocoel and form the _______ producing the _______

A

extraembryonic endoderm
yolk-sac

30
Q

the epiblast will separate into what 2 parts?

A

1) embryonic epiblast
2) amniotic ectoderm

31
Q

from the epiblast:
_______: will form all the tissues of the developing embryo

A

embryonic epiblast

32
Q

from the epiblast:
_______: will form the lining of the amniotic cavity

A

amniotic ectoderm
- secrets amniotic fluid that fills the amniotic cavity. Acts as a shock absorber and prevents desiccation

33
Q

_______: original trophoblast cells that adhere to the endometrium, and remodel maternal vasculature

A

cytotrophoblast

34
Q

_______ formed from cytotrophoblasts that undergo karyokinesis without cytokines creating multinucleated cells

A

syncytiotrophoblast
- remodel
- push embryo deeper into endometrium
- contact mother blood vessels

35
Q

_______ follows syncytiotrophoblasts and continues making connections with maternal tissue and vasculature. Will form the Umbilical Chord

A

extraembryonic mesoderm

36
Q

_______: identical twins

A

monozygotic twins
- one egg

37
Q

Split before formation of the trophoblast will lead to twins that have _______ chorion and _______ amnion

38
Q

Split after formation of the trophoblast will lead to twins that have _______ chorion and _______ amnion

39
Q

Split after amnion formation will lead to twins that have _______ chorion and _______ amnion

A

shared
shared

40
Q

_______: nonidentical twins

A

dizygotic twins
- two egg

41
Q

_______: an individual containing cells from two or more original embryos

A

chimera
- mouse ex with three different 8cell blastulas

42
Q

What are the 2 examples of human chimeras?

A

1) fusion of non-identical twins
2) somatic chimeras (blood type)

43
Q

_______ twins are identical twins who develop with a single _______ from a single fertilization

A

Conjoined
placenta
- will always be same sex, and 3F:1M chance

44
Q

Conjoined twins:
_______: anterior union of the upper half with a shared heart

A

thoracopagus
- most common

45
Q

Conjoined twins:
_______: anterior union of mid trunk

A

omphalopagus

46
Q

Conjoined twins:
_______: posterior union of the rump

47
Q

Conjoined twins:
_______: lateral union of the lower half of the body, variable

48
Q

Conjoined twins:
_______: cranial union only

A

craniopagus
- least common

49
Q

What are the two rare forms of conjoined twins:
_______: asymmetrical conjoined twins, one small and less formed and dependent on the other

A

parasitic twin

50
Q

What are the two rare forms of conjoined twins:
_______: an imperfect fetus is contained completely within the body of its sibling

A

fetus in fetu

51
Q

A/P axis formation in mammals:
The Posterior end has high concentrations of _______, ________, _______, _______

A

1) Wnt
2) Bmp
3) FGF
4) Retinoic acid

52
Q

Retinoic acid is _______ at the posterior end and _______ at the anterior end

A

synthesized
degraded

53
Q

A/P axis formation in mammals:
The Anterior end has high concentrations of _______, and _______

A

Wnt inhibitors
BMP

54
Q

A/P patterning by hox genes in mammals have equivalent genes/gene clusters called _______

A

paralogues/paralogous

55
Q

All mammals have _______ of the HOX complex in haploid genome on 4 chromosomes

A

4 copies
- HOXA, HOXB, HOXC, HOXD in humans
responsive to a wnt gradient

56
Q

Mammals are not completely _______ symmetrical

A

bilaterally
- heart, spleen, stomach, liver, intestines, lungs

57
Q

Major regulatory step: activation of _______ and _______ TF’s on the left side of the lateral plate mesoderm

A

Nodal
Pitx2

58
Q

_______ is found in all 4 and marks the initiation of the blastopore

A

Spemann-Mangold organizor (SMO)