Formation of body plan

Question 1

Hypoblast and epiblast are both formed from the:

Answer 1

ICM

Question 2

The hypoblast surrounds the cytotrophoblast and forms an extraembryonic endoderm now called:

Answer 2

Heuser’s membrane

Question 3

The enclosed cavity of the Heuser’s membrane is now called:

Answer 3

yolk sac

Question 4

A layer of extraembryonic mesoderm will also migrate, from the epiblast, between the Heuser’s membrane and the cytotrophoblast. What does it form?

Answer 4

vasculature of placenta and umbilical cord and first cells of the embryonic blood

Question 5

When the remnant of the yolk sac stays, a small bulge in the small intestine and is the most frequent congenital malformation of the digestive tract. What is this called?

Answer 5

Merkel’s Diverticulum

Question 6

The epiblast will also form a layer of extraembryonic ectoderm, which is a layer of flattened epithelial cells lining a fluid filled cavity called:

Answer 6

amnionic sac

Question 7

In general what does the ectoderm form?

Answer 7

The epidermis and nerves

Question 8

In general what does the mesoderm form?

Answer 8

the notochord, connective tissues, muscle, heart, kidney, gonads but not gametes, cartilage and bone, reproductive system, blood and vasculature

Question 9

In general what does the endoderm form

Answer 9

epithelial lining of lungs, liver, pancreas, digestive tract

Question 10

The infolding of a cell sheet into the embryo is called:

Answer 10

invagination

Question 11

turning in of a cell sheet so that it spreads over the basal surface of an outer layer:

Answer 11

involution

Question 12

migration of surface cells into the interior of the embryo is called:

Answer 12

ingression

Question 13

Spreading of epithelial sheet over deeper cells is called:

Answer 13

epiboly

Question 14

A ridge of cells appear along the midline of the posterior half of the epiblast layer, which is the first sign of gastrulation occurs on which day of human development?

Answer 14

14th

Question 15

The cells along the midline of the epiblast layer is called;

Answer 15

primitive streak

Question 16

Slightly later, a clump of cells gather at the anterior side of primitive streak, it is called:

Answer 16

the node. (hensen’s node in the chick embryo)

Question 17

How is the definitive endoderm formed from epiblast through primitive streak?

Answer 17

The epiblast ingresses through the primitive streak, goes between the epiblast and hypoblast. The first cells to ingress will invade the hypoblast later and displace it to the periphery of the embryo.

Question 18

The mesodermal cells ingress through the node, goes in between the epiblast and endoderm, forming the:

Answer 18

prechordal late and notochord

Question 19

What is the function of the prechordal plate?

Answer 19

a loose population of cells that underlies the developing forebrain. It contributes to the mesodermal population in the head as well as being the signalling center for establishing different populations of neurons in the developing forebrain.

Question 20

How is the notochord important？

Answer 20

It secretes signalling molecules that pattern adjacent tissues such as the neural tube and somites.

Question 21

The notochord degenerates when vertebral column forms; which part of the vertebral column is the notochord retained?

Answer 21

nucleus pulposus of the intervertebral discs.

Question 22

Mesodermal cells flanking the notochord will form three types of mesodermal layers. What are they?

Answer 22

paraxial, intermediate and lateral mesoderm

Question 23

Which mesodermal layer forms the somites?

Answer 23

paraxial

Question 24

In humans, initially there are 40 pairs of somites. How many are the pairs reduced to later?

Answer 24

38

Question 25

The somites divide into three types of cells. What are they?

Answer 25

schlerotome, myotome, dermatome

Question 26

What does schlerotome form?

Answer 26

axial skeletal including the ribs, from the occipital bone to the tail

Question 27

What does myotome form?

Answer 27

striated skeletal muscles

Question 28

What does dermatome form?

Answer 28

the connective tissue of the dermal layer of the dorsal skin

Question 29

What does the intermediate mesoderm form?

Answer 29

blood cells, the kidneys, bladder and reproductive organs (Males: testes, epididymis, vas deferens,
seminal vesicles. Females: ovaries, fallopian tubes, uterus, cervix, most of the vagina).

Question 30

What does the lateral plate mesoderm form?

Answer 30

connective tissue and smooth muscle layers of the digestive tract, connective tissue of the dermal layer of the ventral skin, membranes lining the body cavities,
the skeleton and connective tissues of the limbs, blood vessels and the heart.

Question 31

The nervous system is induced by the underlying axial mesoderm. True or false

Answer 31

True

Question 32

Spemann and Mangold worked on salamander embryos
and grafted prospective notochord of the dorsal blastopore lip (the equivalent to the amniote
node) of an early gastrula stage embryo into the prospective lateral plate mesoderm of a
similarly staged host. They found that it induced a what?

Answer 32

conjoined twin

Question 33

In the amniote, the organizer is:

Answer 33

the node

Question 34

Spemann and Mangold transplanted a prospective notochord in a newt gastrula to its opposite side and conjoined twin was formed. What was the nervous system formed by?

Answer 34

the host cell. The nervous system was formed but would otherwise from the epidermis

Question 35

Cells of the epidermis are striated. True of false?

Answer 35

False. they are cuboidal

Question 36

The ectoderm rostral to the node, and above the notochord and prechordal plate, forms the neural plate, the precursor of the nervous system. Cells of the neural plate elongate to form what type of epithelium?

Answer 36

pseudostratified columnar epithelium

Question 37

As the embryo expands, through cell proliferation, the

primitive streak becomes restricted to the posterior margin of the epiblast, a phenomenon known as:

Answer 37

regression

Question 38

Chordin is believed to form an inhibitor gradient responsible for forming a gradient of BMP4 activity.
BMP4 is the actual morphogen that that specifies the neural plate and neural crest; When BMP4 is fully inhibited, partially inhibited and not inhibited at all, what forms respectively?

Answer 38

neural plate, neural crest, epidermis

Question 39

during human development, the neural tube forms at how many weeks?

Answer 39

4 weeks

Question 40

During closure of the neural tube, which area closes last?

Answer 40

caudal neuropore

Question 41

The neural tube is divided into different regions. The forebrain, midbrain, hindbrain and spinal cord. What are they also called, alternatively, in terms of “cephalon”?

Answer 41

telecephalon and dicephalon; mesencephalon; rhombencephalon

Question 42

The hindbrain is divided into how many rhombomeres?

Answer 42

7

Question 43

The dicephalon includes:

Answer 43

Thalamus, subthalamus,

hypothalamus, epithalamus.

Question 44

When the cranial neural tube fails to close it is called :

Answer 44

ancephaly

Question 45

When the trunk neural tube fails to close it is called

Answer 45

spinal bifida