Limb Development Flashcards
musculature is derived from what portion of the mesoderm
paraxial mesoderm –> myotome
bones are derived from what portion of the mesoderm
lateral plate mesoderm - somatic region
tendons are derived form what portion of the mesoderm
lateral plate mesoderm
somatic region
during the fourth week
both limb buds appear
upper - 24 days
lower - 28 days
during the fifth week, limb development
has reached hand/foot plate development
chondrificaiton occurs
during the sixth week, limb development has reached the stage of
digital rays of hands
limb skeleton is cartilaginous
during the seventh week, limb development has reached the stage of
digital rays of feet have formed
osteogenesis begins
limbs begin to rotate
during the 8th week the limb begins to
form separate digits using BMP signaling (induces cell apoptosis)
by the 12th week of development, the limbs are undergoing
primary ossification
Fgf10 from mesenchyme is responsible for what signaling
activates WNT
WNT induces other Fgfs
sets up positive feedback loop FGF–> WNT–>FGF–>WNT
sets up primary gradient
Apical ectodermal ridge controls which axis
proximal/distal axis
AER responsible for continued outgrowth
secretes Fgf8
Fgf8 is primarily secreted by
the Apical ectodermal ridge (AER)
Fgf8 is a key regulator of _______ and interacts with ______
key regulator of distal outgrowth
interacts with Fgf10
hox gene expression pattern correlates with
identity elements along proximal distal axis
9-10 –> styolopod
11 –> zeugopod
12-13 –> autopod
Zone of polarizing activity controls what axis development
controls AP axis
induced by Shh activity
Shh is associated with the ______ to designate which axis
zone of polarizing activity AP axis (pinky vs thumb)
paralog
gene related to each other due to descent from a common ancestral DNA sequence (commonly duplication)
AP axis specification occurs even before
limb bud outgrowth
grafting Shh onto the anterior portion of a growing limb bud will result in
mirrored medial digits (more pinkies)
primary molecular regulator of dorsal/ventral axis
Wnt7a controlled by Lmx1b
Wnt7a activity is associated with which surface of distal limb
Wnt7a does dorsalization
BMP controls what process of limb development
formation of digits through apoptosis
dorsal mass forms ______ and _____ of upper limb but forms the ________ and _______ of lower limb
dorsal
extensors and supinators of upper
extensors and abductors of lower
ventral mass forms ______ and ______ of upper limb but forms the _______ and _______ of lower limb
ventral
flexors and pronators of upper limb
flexors and adductors of lower limb