Chapter 12 mammals

Question 1

Mammalian development leads to _______ cleavage

Answer 1

rotational

Question 2

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

Answer 2

meridional
asymmetrical
- one is meridional while the other is equitorial

Question 3

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

Answer 3

compaction

Question 4

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

Answer 4

E-cadherins

Question 5

Compacting cells are stabilized by _______ junctions

Answer 5

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

Question 6

Compacting cells form _______ junctions, allowing communication via small molecules

Answer 6

gap

Question 7

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

Answer 7

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

Question 8

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

Answer 8

Cdx2 & Oct4

Question 9

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

Answer 9

Yap

Question 10

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

Answer 10

Tead4

Question 11

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

Answer 11

Hippo
lats

Question 12

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

Answer 12

Yap

Question 13

Describe the process of determining trophoblast cells?

Answer 13

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)

Question 14

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

Answer 14

blastocoel

Question 15

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

Answer 15

cavitation

Question 16

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

Answer 16

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

Question 17

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

Answer 17

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

Question 18

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

Answer 18

trypsin-like protease

Question 19

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

Answer 19

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

Question 20

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

Answer 20

L-selectin

Question 21

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

Answer 21

integrins and P-cadherins

Question 22

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 _______

Answer 22

implantation

Question 23

Implantation is mediated by signals involving _______ protein signals

Answer 23

Wnt

Question 24

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

Answer 24

1) Collagenases
2) Stromelysin
3) Plasminogen activator

Question 25

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

Answer 25

placenta

Question 26

What are the 2 parts of the placenta?

Answer 26

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

Question 27

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

Answer 27

chorion

Question 28

The inner cell mass cells divide into the _______

Answer 28

bilayer germinal blastodisk - will delaminate to form epiblast and hypoblast

Question 29

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

Answer 29

extraembryonic endoderm yolk-sac

Question 30

the epiblast will separate into what 2 parts?

Answer 30

1) embryonic epiblast 2) amniotic ectoderm

Question 31

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

Answer 31

embryonic epiblast

Question 32

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

Answer 32

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

Question 33

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

Answer 33

cytotrophoblast

Question 34

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

Answer 34

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

Question 35

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

Answer 35

extraembryonic mesoderm

Question 36

_______: identical twins

Answer 36

monozygotic twins - one egg

Question 37

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

Answer 37

own own

Question 38

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

Answer 38

shared own

Question 39

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

Answer 39

shared shared

Question 40

_______: nonidentical twins

Answer 40

dizygotic twins - two egg

Question 41

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

Answer 41

chimera - mouse ex with three different 8cell blastulas

Question 42

What are the 2 examples of human chimeras?

Answer 42

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

Question 43

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

Answer 43

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

Question 44

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

Answer 44

thoracopagus - most common

Question 45

Conjoined twins: _______: anterior union of mid trunk

Answer 45

omphalopagus

Question 46

Conjoined twins: _______: posterior union of the rump

Answer 46

pyropagus

Question 47

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

Answer 47

parapagus

Question 48

Conjoined twins: _______: cranial union only

Answer 48

craniopagus - least common

Question 49

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

Answer 49

parasitic twin

Question 50

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

Answer 50

fetus in fetu

Question 51

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

Answer 51

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

Question 52

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

Answer 52

synthesized degraded

Question 53

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

Answer 53

Wnt inhibitors BMP

Question 54

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

Answer 54

paralogues/paralogous

Question 55

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

Answer 55

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

Question 56

Mammals are not completely _______ symmetrical

Answer 56

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

Question 57

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

Answer 57

Nodal Pitx2

Question 58

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

Answer 58

Spemann-Mangold organizor (SMO)