A
STOP
α-cardiac actin
nlaacZ
nlacZ
α-cardiac actin
βgal+
αc-actin expression domain
E14.5
skeletal muscles and heart myocardium
early recombination event
B
STOP
α-cardiac actin
nlaacZ
α-cardiac actin
nlacZ
βgal+
αc-actin expression domain
skeletal muscles and heart myocardium
late recombination event
E14.5