Chapter 13- Reporting

Question 1

• the bones of any tetrapod limb, be it arm
  or leg, wing or flipper

Answer 1

stylopod

Question 2

(radius-ulna/tibia-fibula) in the middle of
the region

Answer 2

zeugopod

Question 3

• (Carpals-fingers/Tarsals-Toes)

Answer 3

autopod

Question 4

• is the set of processes by which
  embryonic cells form ordered spatial arrangements of
  differentiated tissues

Answer 4

pattern formation

Question 5

is an extremely complex organ
with an asymmetrical arrangement of parts.

Answer 5

vertebrate limb

Question 6

The first dimension is the _______________________
(“close-far”; shoulder-finger or hip-toe). The bones of the limb are formed by endochondral ossification.

Answer 6

Proximal-distal axis

Question 7

The second dimension is the_______________ (thumb-pinkie). Our little fingers or toes mark the Posterior side, while our thumbs or big toes are at the
anterior end.

Answer 7

Anterior-Posterior Axis

Question 8

limbs have a _________________: our palms
(ventral) are readily distinguishable from our
knuckles (dorsal).

Answer 8

Dorsal-Ventral Axis

Question 9

what is the step for the development of the tetrapod limb?

Answer 9

• A. Proliferation of mesenchymal cells
• B. Entry of myoblast (purple) into the limb bud

Question 10

This larger region, representing all the cells in the area capable of forming a limb, is called the ______________.

Answer 10

limb field

Question 11

These mesenchymal cells accumulate under the ectodermal tissue to create a circular bulge called a ________________

Answer 11

limb bud

Question 12

• This is capable of initiating the limb forming interactions between ectoderm and mesoderm.
• capable of initiating the limb-forming interactions between the
  ectoderm and the mesoderm

Answer 12

Fgf10

Question 13

The loss-of-function data were equivocal:
humans heterozygous for the TBX5 gene
have ____________________, characterized
by abnormalities of the heart and upper
limbs (Basson et al. 1996; Li et al. 1996).
The legs are not affected, but neither are
the arms transformed into a pair of legs

Answer 13

Holt-Oram syndrome

Question 14

As mesenchyme cells enter the limb region, they secrete factors
that induce the overlying ectoderm to form a structure called the ___________________

Answer 14

apical ectodermal ridge (AER)

Question 15

This ridge runs along the distal margin of the limb bud and will become a major signaling center for the developing limb. Its roles include

Answer 15

• (1) maintaining the mesenchyme beneath it in a plastic, proliferating phase that enables the linear (proximal-distal) growth of the limb;
• (2) maintaining the expression of those molecules that generate the anterior posterior (thumb-pinky) axis; and
• (3) interacting with the proteins specifying the anterior posterior and dorsal-ventral axes so that each cell is given instructions on how to differentiate.

Question 16

is capable of inducing the AER in the
competent ectoderm between the dorsal and ventral sides of the embryo.

Answer 16

FGF10

Question 17

The proximal-distal growth and differentiation of the limb bud is made possible by a series of interactions between the _________________________________

Answer 17

limb bud mesenchyme and the AER.

Question 18

The AER initiates limb bud elongation by promoting the ___________________ cells underneath it

Answer 18

proliferation of mesenchyme

Question 19

is the region of cell division
responsible for this elongation, and it extends about 200 μm in from the AER.

Answer 19

progress zone

Question 20

if an FGF-containing bead is
placed in the hole left by the removal of the AER, a normal limb will form. This process is known as the

Answer 20

FGF- induced limb regeneration

Question 21

first cells to leave
the PZ

Answer 21

proximal (stylopod) structures

Question 22

When older AERs combined with younger mesoderm should produce _____________________________

Answer 22

limbs with deletions in the middle

Question 23

When younger AERs combined with older mesoderm should produce ________________________

Answer 23

duplications of structures

Question 24

who invented the activator-inhibitor model?

Answer 24

Newman and Baht

Question 25

The limb bud becomes subsequently patterned into three areas:

Answer 25

1st, 2nd, 3rd domain

Question 26

is the earliest restriction in limb bud cell
potency from the pluripotent condition

Answer 26

specification of the anterior-posterior axis

Question 27

A region in the mesoderm where the
anterior-posterior axis is specified

Answer 27

zone of polarizing activity

Question 28

• plays a role in specifiying the location
  where the limbs will form
  ● They also play a secondary role of specifying
  whether a particular mesenchymal cell will become stylopod, zeugopod, or or autopod
  ● Its also plays another role in specifying both the ZPA and the identity of the digits and specifying code for limb skeleton identity

Answer 28

Hox genes

Question 29

molecule that is important in specifying
dorsal-ventral polarity

Answer 29

Wnt7a

Question 30

The synthesis of Sonic hedgehog is stimulated by the combination of ______________________

Answer 30

Fgf4 and Wnt7a proteins

Question 31

This is crucial for the formation of joints and separation of fingers in the tetrapod limb.

Answer 31

cell death

Question 32

They are separated from each other by an
interior necrotic zone, and two other regions, the anterior and
posterior necrotic zones

Answer 32

ulna and radius

Question 33

is synthesized in the perichondrial cells
surrounding the condensing chondrocytes and
promotes cartilage formation

Answer 33

BMP7

Question 34

without feathers, resembles a small
coelurosaur, such as Jurassic Park’s Velociraptor

Answer 34

archaeopteryx

Question 35

This is a negative regulator of the Wnt/β-catenin signaling pathway

Answer 35

Dkk-1

Question 36

front nears cartilage ends of the
cartilage model

Answer 36

ossification

Question 37

Bone formation before birth limits ________ and _______

Answer 37

growth and size

Question 38

spreads outward in long
bones of mammals, including humans.

Answer 38

endochondral ossification

Question 39

cartilaginous areas at the
end of the long bones

Answer 39

epiphyseal growth plates

Question 40

Epiphyseal Three Regions:

Answer 40

➢ Region of Chondrocyte
Proliferate
➢ Region of Mature Chondrocytes
➢ Region of Hypertrophic
Chondrocytes

Question 41

inhibit proliferation of epiphyseal growth plate cells and facial cartilage.

Answer 41

fibroblast growth factors

Question 42

dominant condition, is caused by
mutations in the transmembrane region of FGF receptor 3.

Answer 42

achondroplasia

Question 43

Mutations in the extracellular portion or tyrosine kinase intracellular domain can result in _________________________, a lethal form of dwarfism
resembling homozygous achondroplasia.

Answer 43

thanatophoric dysplasia

Question 44

• is essential for bone development in both
  males and females.
• regulates bone growth, even in men, with
  some cases indicating continued growth in adulthood without estrogen.

Answer 44

estrogen

Question 45

are found on growth
hormone-regulating cells and all human growth plate cells.

Answer 45

estrogen receptors

Question 46

stimulate skeletal growth, while
high levels induce apoptosis and invasion of
osteoblasts into the growth plate.

Answer 46

low estrogen levels

Question 47

occurs when osteoblasts stop
growing without further cartilage formation.

Answer 47

growth plate closure

Question 48

This is required for maintaining chondrocyte cell division and preventing hypertrophy. In humans, loss-of-function mutations can cause severe growth defects.

Answer 48

Parathyroid hormone-related peptide