Question 1

What determines the orientation of the antero-posterior axis in the epiblast of a chick embryo?&#10;A) A random process&#10;B) Interaction with the surrounding albumin&#10;C) Gravity effects on the embryo&#10;D) It is oriented away from the site of sperm entry

Accepted Answer

Gravity effects on the embryo determine the orientation of the antero-posterior axis in the epiblast of a chick embryo.

Question 2

Which of the options given is the Nieuwkoop center analog in the chick embryo?&#10;A) Anterior marginal zone&#10;B) Posterior marginal zone&#10;C) Area pellucida&#10;D) Area opaca

Accepted Answer

The Nieuwkoop center, which is crucial in establishing the body axis during early development in amphibians, has an analog in the chick embryo known as the Posterior marginal zone (PMZ). This region plays a similar role in axis formation and germ layer specification in avian embryos.

Question 3

Which of the following is not true of the trophectoderm?&#10;A) Cells on the morula's periphery tend to become trophectoderm&#10;B) Formation of the trophectoderm is the first differentiation event in mammalian embryonic development&#10;C) The transcription factor Oct4 promotes trophectoderm formation&#10;D) Mouse chimeras have been used to study trophectoderm specification

Accepted Answer

The transcription factor Oct4 actually promotes the formation of the inner cell mass (ICM) and inhibits trophectoderm formation, not the other way around.

Question 4

What is the result of Gata6 expression within the inner cell mass?&#10;A) Cells differentiate into a layer of primitive endoderm&#10;B) Cells differentiate into trophoblasts&#10;C) Cells differentiate into epiblast&#10;D) Cells revert back to a more pluripotent state

Accepted Answer

Gata6 expression within the inner cell mass leads to the differentiation of cells into a layer of primitive endoderm, which is essential for the development of the embryo.

Question 5

What is another way of referring to the paraxial mesoderm?&#10;A) Intermediate mesoderm&#10;B) Somitic mesoderm&#10;C) Lateral plate mesoderm&#10;D) Notochord

Accepted Answer

The paraxial mesoderm is also known as the somitic mesoderm because it segments into somites, which are structures that give rise to the vertebrae, ribs, and associated musculature.

Question 6

What is the signaling protein responsible for initiating neural tissue induction in the chick embryo?&#10;A) FGF&#10;B) BMP&#10;C) Chordin&#10;D) Cerberus

Accepted Answer

FGF (Fibroblast Growth Factor) is responsible for initiating neural tissue induction in the chick embryo. It plays a crucial role in the early stages of neural development by signaling ectodermal cells to become neural cells.

Question 7

Which of the following is not true of somites?&#10;A) Somites give rise to bone, cartilage, and muscle of the body axis&#10;B) Two somites form simultaneously&#10;C) Somites form rhythmically from posterior to anterior&#10;D) Somites are formed from mesoderm adjacent to the neural tube

Accepted Answer

Somites form rhythmically from the anterior to the posterior, not from posterior to anterior. They are segments of mesoderm located on either side of the neural tube in the developing embryo, which give rise to the vertebral column, rib cage, and part of the skull, as well as the dermis of the skin and skeletal muscles.

Question 8

What does the &#34;clock and wavefront&#34; model propose?&#10;A) Cells must undergo a specific number of oscillations of gene activity in order to form a somite&#10;B) Cells must be passed by the wavefront to commit to forming a somite&#10;C) Cells must not have yet been passed by the wavefront to commit to forming a somite&#10;D) Genes that position a wavefront have clock-like gene expression

Accepted Answer

The answer of What does the &#34;clock and wavefront&#34; model...

Question 9

Which of the following genes determines the identity of somites in mouse and chick embryos and can be disrupted in order to induce transformations or antero-posterior shifts in vertebral fate?&#10;A) Hox&#10;B) BMP&#10;C) Fgf&#10;D) Notch

Accepted Answer

Hox genes are responsible for determining the identity of somites in mouse and chick embryos. They play a crucial role in the antero-posterior patterning of the embryo, leading to the correct development of vertebral types in specific body regions. Disruptions in Hox gene function can result in transformations or shifts in vertebral identity along the antero-posterior axis.

Question 10

The sclerotome region of a somite gives rise to vertebrae and ribs. From which tissues does the sclerotome receive signals to direct these fates?&#10;A) Lateral plate mesoderm&#10;B) Notochord and floor plate&#10;C) Roof plate and overlying ectoderm&#10;D) Endoderm

Accepted Answer

The sclerotome region of a somite receives signals from the notochord and floor plate, which are essential for directing the development of vertebrae and ribs. These signals are crucial for the differentiation and patterning of the sclerotome into skeletal structures.

Deck 5: Laying Down and Completing the Vertebrate Body Plan: Chick and Mouse