Vertebrate Development IV

Question 1

T or F: relatively little is known about the early stages in chick development as they take place before the egg is laid

Answer 1

TRUE

Question 2

The antero-posterior polarity of the chick blastoderm is related to the ___1.___

Answer 2

1. primitive streak

Question 3

Cleavage begins after ___1.___ while the egg is still in the hen’s ___2.___

Answer 3

1. fertilization

2. oviduct

Question 4

At the time of laying, the embryo is a ___1.___ cellular blastoderm lying on top of a ___2.___ , which is surrounded by the egg white and shell

Answer 4

1. disc-shaped

2. massive yolk

Question 5

The ___1.___ indicates the direction of the antero-posterior axis of the embryo, with the node called ___2.___ node forming at its ___3.___ end

Answer 5

1. primitive streak
2. Hensen’s
3. anterior

Question 6

T or F: it is not clear whether any maternal factors are inherited asymmetrically during cleavage and determine the embryonic axis

Answer 6

TRUE

Question 7

The ___1.___ axis seems to be specified later, as a result of ___2.___ forces as the egg passes through the hen’s ___3.___ and ___4.___

Answer 7

1. antero-posterior
2. rotational
3. oviduct
4. uterus

Question 8

KEY POINT: ___1.___ gene activation occurs at late ___2.___ stages!

Answer 8

1. zygotic

2. cleavage

Question 9

T or F: the antero-posterior axis is irreversibly determined by rotational forces of the egg

Answer 9

FALSE (it is not irreversibly)

Question 10

T or F: Even at the stage when the blastoderm contains several tens of thousands of cells, it can be cut into many fragments each of which will develop a complete embryonic axis

Answer 10

TRUE

Question 11

The ___1.___ zone can be thought of as an ___2.___ center analogous in some ways with the ___3.___ in Xenopus

Answer 11

1. posterior marginal
2. organizing
3. Nieuwkoop center

Question 12

T or F: the mammalian egg differs considerably from the eggs of either the frog or the chick

Answer 12

TRUE

Question 13

T or F: the early cleavage divisions in mouse embryos follow a well-ordered pattern

Answer 13

FALSE (they do NOT follow a well-ordered pattern aka regulative development)

Question 14

By the ___1.___ cell stage, the morula has developed into a ___2.___

Answer 14

1. 32

2. blastocyst

Question 15

The development of cells as either ___1.___ or ___2.___ in early mouse embryos depends on their position in the cleaving embryo

Answer 15

1. inner cell mass

2. trophectoderm

Question 16

Determination of their fate occurs after the ___1.___, and during earlier stages all the cells seem to be equivalent in their ability to give rise to either tissue

Answer 16

1. 32-cell stage

Question 17

The cells of the ___1.___ are ___2.___ and can give rise to all cell types of the embryo including ___3.___ , in vitro

Answer 17

1. epiblast
2. pluripotent
3. germ cells

Question 18

The embryonic-abembryonic axis corresponds in a geometric sense to the ___1.___ axis of the future ___2.___ , but not in terms of cell fate

Answer 18

1. dorso-ventral

2. epiblast

Question 19

The formation of the ___1.___ appears at the ___2.___ end of the antero-posterior axis in the epiblast

Answer 19

1. primitive streak

2. posterior

Question 20

The ___1.___ of the epiblast cup corresponds to the ___2.___ side of the future embryo and outer side to the future ___3.___ side

Answer 20

1. anterior
2. dorsal
3. ventral

Question 21

T or F: mesoderm induction and patterning in the chick and mouse occurs during primitive streak formation, with different regions of the streak giving rise to different mesodermal tissues along the dorso-ventral axis

Answer 21

TRUE

Question 22

___1.___ family members can act as mesoderm-inducing and/or ___2.___-patterning signals

Answer 22

1. TGF-beta

2. mesoderm

Question 23

The node that develops at the ___1.___ end of the streak in ___2.___ and mouse embryos is equivalent to the ___3.___ in Xenopus

Answer 23

1. anterior
2. chick
3. Spemann

Question 24

T or F: after extending to its full length, the primitive streak begins to regress anteriorly

Answer 24

FALSE (posteriorly instead of anteriorly)

Question 25

As it does so, the ___1.___ (head process) is formed by ___2.___ cells that emerged from the ___3.___ tip of the streak and moves ___4.___

Answer 25

1. notochord
2. mesodermal
3. anterior
4. forward

Question 26

The ___1.___ and ___2.___ overlying the head process form in the epiblast ___3.___ to the furthest extent of the ___4.___

Answer 26

1. head fold
2. neural plate
3. anterior
4. primitive streak

Question 27

The edges of the ___1.___ begin to rise up to form the ___2.___ and the first ___3.___ appears

Answer 27

1. neural plate
2. neural folds
3. somite

Question 28

___1.___ induction in chick and mouse is initiated by ___2.___ signaling with inhibition of ___3.___ signaling being required in a later step

Answer 28

1. Neural
2. FGF
3. BMP

Question 29

___1.___ are formed in a well-defined order along the antero-posterior axis

Answer 29

1. Somites

Question 30

Identity of somites along the ___1.___ axis is specified by ___2.___ gene expression

Answer 30

1. antero-posterior

2. Hox

Question 31

Deletion or overexpression of ___1.___ gene causes changes in ___2.___ patterning

Answer 31

1. Hox

2. axial

Question 32

The fate of somite cells is determined by signals from the ___1.___

Answer 32

1. adjacent tissues

Question 33

Which internal organs are asymmetric (left-right asymmetry)?

Answer 33

Heart and liver

Question 34

T or F: left-right asymmetry involves an initial symmetry-breaking event leading to asymmetric gene expression on the left and right sides of the embryo

Answer 34

TRUE

Question 35

The activity of proton-potassium pump in ___1.___ node is reduced on the left side of the node, leading to a membrane-potential difference across the node and increased release of ___2.___ into the extracellular space on the ___3.___ side of the node

Answer 35

1. Hensen’s
2. calcium
3. left

Question 36

This leads to a greater activation of ___1.___ signaling on the ___2.___ side of the node which in turn activates expression of the gene ____3.___ in cells on the left side of the node

Answer 36

1. Notch
2. left
3. Nodal

Question 37

___1.___ signaling together with ___2.___ then switches on Nodal expression on the ___3.___ side, which leads to expression of the transcription factor ___4.___

Answer 37

1. Nodal
2. Sonic hedgehog (Shh)
3. left
4. Pitx2