EMBRYO Flashcards
what are the 3 main axes of coordination?
proximal-distal: AER
anterior-posterior: ZPA
dorsal-ventral: ectoderm
High concentration of morphogens in ZPA
5th digit and posterior structures
Low concentration of morphogens in ZPA
2nd digit and anterior structures
No morphogens (No concentration)
1st digit and anterior
what defines the mesoderm?
paraxial
intermediate
VLPM
PLPM
the paraxial mesoderm produces what?
axial skeleton
all skeletal muscle
the intermediate mesoderm produces what?
urinary system
reproductive system
VLPM of the mesoderm produces?
cardiovascular system
GI/resp tract lining and smooth muscle
PLPM of the mesoderm produces?
appendicular skeleton
what are the layers of the paraxial mesoderm?
sclerotome dermomyotome -myotome --epimere (body wall) --hypomere (back muscles) -dermotome
in the 4th week, what are visible?
limb buds
when are the limbs formed?
by the 8th week
what induces adjacent mesoderm to continue to proliferate and
remain undifferentiated in proximal-distal limb axis (aka proximal zone)
AER
specific
ectodermal specializations
Mesoderm begins differentiation once AER has migrated past it
🡪induces formation of limb
caudal orientation
differentiation
Retinoic acid from cells of zone of polarizing activity (ZPA) directs cranial
Retinoic acid highest for which digit?
thumb
Upper limbs will be profused by the _____?
the median artery
*replaced by radial and ulnar arteries
lower limbs are professed by _____?
Umbilical artery -> Axis Artery > perfusion of lower limb
Adult pattern of arterial supply is reached by:
8th Intrauterine
week
arterial supply for lower limb?
femoral artery
axis artery
extension of new EXTERNAL ILIAC ARTERY
Femoral Artery
starts as capillary plexus from the UMBILICAL ARTERY
Axis Artery
important genes expressed at the LPM prior to limb growth?
Tbx-5 cranially and Tbx-4 caudally
name this gene expressed at the LPM?
expression therefore causes the limb bud to form into an arm
Tbx-5
name this gene expressed at the LPM?
region will form a leg
Tbx-4
