Snakes have lost their limbs over the course ofevolution. Recent data show a reduction in Shhexpressionin their limb fields due to loss of a portion of the limb enhancer,noting that other enhancers remain intact.
First, indicate whether this is an example of heterotopy,heterochrony, heterometry, or heterotypy, defining your chosenterm. Second, describe how you might use the mouse embryo as amodel system to test the hypothesis that this reduction inShh expression in the limb field is responsible for theloss of limbs in snakes. Be sure to provide a brief description ofthe relevant technique(s), and to include at least one control
