Study Questions 7-8 Flashcards
Define Somatopleure and which germ layer is involved in its formation
Dorsal layer where mesoderm splits into. Formed from ecto and mesoderm
Define Splanchnopleure and which germ player is involved in its formation
Ventral layer wehre mesoderm splits into. Fromed from endoderm and mesoderm
What is the role of the endoderm in the migration of cardiac precursor cells?
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
Define hemangioblast
percursor cell for endothelial cells and hematopoetic stem cells (angioblast and pluripotent HSC)
Define pluripotent HSC
stem cell used for haemotopoiesis that produces all blood cells and lymphocytes
Define Angioblast
cells that are progenitors of blood vessels- becomes endothelial cells that liine blood vessels
What is vasculogenesis and where does it occur?
It is the creation of blood vessels, and occurs in blood islands of the yolk sac
What is angiogenesis
The remodeling of blood vessels to form capillary bed, veins and arteries
What are the two theories about possible vascular tube lumen formation?
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
Define organ specific angiogenesis
peripheral neurons and associated schwann cells secrete VEGF which induces arteries
What is the concept of a stem cell?
self renewing and can differentiate into a number of fates
What is AGM?
aorta-gonad-mesonephros region
region of the visceral lateral plate mesoderm near the aorta, produces hemotopoetic stem cells
What is derived from the endodermal germ layer?
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
Name three organs that develop as outgrowths of the early digestive system and name one function for each of these organs
liver-filter harmful substances from blood
pancreas- breakdown proteins, carbs and fats
gallbladder- store bile and concentrate
Define proximal-distal axis
Stylopod, Zeugopod, Autopod. Arranged poximal to distal
Define anterior-posterior axis
pinky posterior, thumb anterior
Define dorsal ventral axis
palm ventral, knuckles and nails dorsal
What is the role of Fgf10,Fgf8, Wnt2b, Wnt8c and Wnt3a in the initiation of the chicken limb bud formation
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
What is the role of FGF10, Tbx5 and Tbx4 in limb bud formation in the chick
FGF10- induces limb formation
Tbx5- specifies the forelimbs
Tbx4- specifies hindlimbs
What is AER
apical ectoderma ridge- directs how the limb is going to grow
what is PZ
the progress zone
Hoe does AER and PZ work together to govern limb gorwth?
AER interacts with the limb bud mesenchyme PZ which is directly below it
outline the results of grafting expreiments which defined AER and PZ interaction
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
What is the role of Shh in anterior-posterior limb axis determination
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
What is the role of BMPs in digit formation
influence webbing and apoptosis that defines digit formation
What is the signaling pathway responsible for dorsal-ventral limb axis formation?
Lmx1 induced by Wnt7a which is used to induce dorsal fate
What type of morphogene is Lmx1?
it is a LIM-homeodomain transcription factor
