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Embrology: limb development
limb development by Paulsen
45
Medical
Professional
09/27/2011

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Term
the layer from which limb buds arise.
Definition
somatic layer of the lateral plate mesoderm
Term
the 2 layers of the lateral plate mesoderm
Definition
somatopleure and splanchnopleure
Term
Forms epidermis & derivatives (hairs, nails, sweat & sebaceous glands
Definition
the ectoderm
Term
Forms dermis, connective tissue, tendons, cartilage, bone, & muscle
Definition
the mesoderm
Term
plane of asymmetry that means toward the stomach
Definition
distal
Term
plane of asymmetry that means caudal
Definition
posterior
Term
plane of asymmetry that means cranial
Definition
anterior
Term
plane of asymmetry that means toward the back
Definition
dorsal
Term
the structure that divides the ventral and dorsal part of the developing embryo
Definition
apical ectodermal ridge
Term
the plane of the body associated with limb outgrowth
Definition
proximodistal
Term
the plane of the body associated with asymetric digit specification
Definition
anteroposterior
Term
the plane of the body associated with the AER posistion and muscle pattern
Definition
dorsoventral
Term
extensor muscles are found on the ____ side
Definition
dorsal
Term
flexor muscles are found on the ____ side of the arm
Definition
wentral
Term
What is induced by underlying mesenchyme, secretes FGF-* and FGF-4, maintains the progress zonem and is required for limb-bud outgrowth
Definition
Apical Ectodermal Ridge
Term
What is induced by AER, secretes FGF-10, maintains AER, inhibits differentiation, rapid cell divison, and is required for limb- bud outgrowth
Definition
progress Zone (PZ)
Term
Distal-to-proximal limb patterning corresponds to nested 5’-to-3’ expression of _____ genes
Definition
homeobox (Hoxd) genes
Term
FGF-4 and FGF-8 maintains what gene expression in the PZ
Definition
Hoxd13
Term
Cells left behind by distally-growing PZ lose expression of _____ and differentiate first.
Definition
5’-HoxD genes
Term
the first cells left behind during limb bud outgrowth represent
Definition
the most proximal limb structures
Term
the last cells left behind during limb bud outgrowth specifiy
Definition
more distal limb structures
Term
a mouse that is knockout for what gene lacks what 2 important bones and is an indication of genetic specification of proximal distal pattern of limb bud outgrowth
Definition
hox11/ radius and ulna
Term
an area that is located on the postrior border of the limb and confers anterior and posterior asymetry to a limb
Definition
ZOne of Polarizing Activity
Term
what happend when a ZPA graft is placed on a developing chick wing
Definition
a doubling of the hand occurs (digit respecification)
Term
a compound in increased concentrations kills off ZPA and can induce digit respecification, causes the expression of ectopic Shh expression
Definition
retinoic Acid
Term
a normal product of the ZPA region, induces FGF-4 secretion by AER (integration of proximodistal with anteroposterior patterning)
Definition
Shh
Term
Shh implants can induce _______
Definition
skeletal duplication
Term
Shh induced this expression
Definition
Hoxd
Term
this gene expression is restricted to the dorsal ectoderm and induces Lmx1 in the dorsal mesoderm
Definition
Wnt7a
Term
Wnt7a knockouts fail to form what structure
Definition
apical ectodermal ridge
Term
this gene expression is restricted to the ventral ectoderm and inhibits r-fing in the dorsal ectoderm expressing Wnt7a
Definition
En1
Term
during limb histogenesis the _____ follows and innervates peripherally migrating muscle mass
Definition
dorsal and ventral brances of ventral primary rami
Term
during muscle limb histogenesis the myotome devides into what
Definition
dorsal and ventral muscle masses on either side of the precursor bones and tendons
Term
the ventral primary rami of spinal nerves provides.....
Definition
the limb motor supply and cutaneous innervation
Term
at 6 weeks the limbs bend in what direction
Definition
anteriorly
Term
at what stage do the upper and lower limbs undergo 90 degree torsion along the long axis so that the elbows point caudally and the knees point cranially
Definition
at 7 weeks
Term
the name of the torsion of the lower limbs that results at 8 weeks, and the arrangement of their cutaneos innervation
Definition
twisted or barber pole arrangement
Term
If the final rotation does not occur in the lower limbs of a fetus what results
Definition
club foot
Term
the complete absence of a limb
Definition
amelia
Term
when digits are fused
Definition
syndactyly
Term
what cellular process is critical in the formation of fingers and toes
Definition
apoptosis
Term
more than 5 digits on a hand
Definition
polydactyly
Term
when the hands are attached to the scapula
Definition
phocomelia
Term
a type of limb defect that causes the formation of an extra limb and can be cause by retinoic acid
Definition
polymelia
Term
meromelia
Definition
a birth defect characterized by the lacking of a part, but not all, of one or more limbs with the presence of a hand or foot. It results in a shrunken and deformed extremity
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