Study Questions 7-8

Question 1

Define Somatopleure and which germ layer is involved in its formation

Answer 1

Dorsal layer where mesoderm splits into. Formed from ecto and mesoderm

Question 2

Define Splanchnopleure and which germ player is involved in its formation

Answer 2

Ventral layer wehre mesoderm splits into. Fromed from endoderm and mesoderm

Question 3

What is the role of the endoderm in the migration of cardiac precursor cells?

Answer 3

The foregut endoderm controls the migration of the heart cells at the end of day one betwen the ectoderm and endoderm toward the middle of the embryo

Question 4

Define hemangioblast

Answer 4

percursor cell for endothelial cells and hematopoetic stem cells (angioblast and pluripotent HSC)

Question 5

Define pluripotent HSC

Answer 5

stem cell used for haemotopoiesis that produces all blood cells and lymphocytes

Question 6

Define Angioblast

Answer 6

cells that are progenitors of blood vessels- becomes endothelial cells that liine blood vessels

Question 7

What is vasculogenesis and where does it occur?

Answer 7

It is the creation of blood vessels, and occurs in blood islands of the yolk sac

Question 8

What is angiogenesis

Answer 8

The remodeling of blood vessels to form capillary bed, veins and arteries

Question 9

What are the two theories about possible vascular tube lumen formation?

Answer 9

1- vacuoles within endothelial merge together to form larger vacuoles and fuse with cell membrane to make lumen
2- vacuoles from intracellular lumina within each cell, lumina fuse with cell lining and lumen forms across the cells

Question 10

Define organ specific angiogenesis

Answer 10

peripheral neurons and associated schwann cells secrete VEGF which induces arteries

Question 11

What is the concept of a stem cell?

Answer 11

self renewing and can differentiate into a number of fates

Question 12

What is AGM?

Answer 12

aorta-gonad-mesonephros region

region of the visceral lateral plate mesoderm near the aorta, produces hemotopoetic stem cells

Question 13

What is derived from the endodermal germ layer?

Answer 13

Lining epithelia of:
-mouth tongue, tonsils,
-stomach, instestines
-bladder and urethra
-repiratory tract
Glands:
-Edocrine: Thyroid and parathyroid, thymus, islets of langerhans
-Exocrine- pancreas, prostatic glands

Question 14

Name three organs that develop as outgrowths of the early digestive system and name one function for each of these organs

Answer 14

liver-filter harmful substances from blood
pancreas- breakdown proteins, carbs and fats
gallbladder- store bile and concentrate

Question 15

Define proximal-distal axis

Answer 15

Stylopod, Zeugopod, Autopod. Arranged poximal to distal

Question 16

Define anterior-posterior axis

Answer 16

pinky posterior, thumb anterior

Question 17

Define dorsal ventral axis

Answer 17

palm ventral, knuckles and nails dorsal

Question 18

What is the role of Fgf10,Fgf8, Wnt2b, Wnt8c and Wnt3a in the initiation of the chicken limb bud formation

Answer 18

FGF10- paracrine factor expressed initially throughout lateral plate mesoderm
Expression of limb bud- Wnts
Wnt2b- forlimb
Wnt8c- hindlimb
Expression of lateral plate Wnt3a regulates expression of ectoderm limb buds

Question 19

What is the role of FGF10, Tbx5 and Tbx4 in limb bud formation in the chick

Answer 19

FGF10- induces limb formation
Tbx5- specifies the forelimbs
Tbx4- specifies hindlimbs

Question 20

What is AER

Answer 20

apical ectoderma ridge- directs how the limb is going to grow

Question 21

what is PZ

Answer 21

the progress zone

Question 22

Hoe does AER and PZ work together to govern limb gorwth?

Answer 22

AER interacts with the limb bud mesenchyme PZ which is directly below it

Question 23

outline the results of grafting expreiments which defined AER and PZ interaction

Answer 23

1-AER is removed development ceases
2-If AER is added extra limbs formed
3- if PZ placed below wing AER, toes form at end of limb
4-If PZ replaced by non-limb mesenchyme then AER regresses and limb development stops

Question 24

What is the role of Shh in anterior-posterior limb axis determination

Answer 24

maintains FGFs expression in the AER

Digit specification is dependent on the time Shh is expressed and the concentration of Shh that other cells recieve

Question 25

What is the role of BMPs in digit formation

Answer 25

influence webbing and apoptosis that defines digit formation

Question 26

What is the signaling pathway responsible for dorsal-ventral limb axis formation?

Answer 26

Lmx1 induced by Wnt7a which is used to induce dorsal fate

Question 27

What type of morphogene is Lmx1?

Answer 27

it is a LIM-homeodomain transcription factor