In comparing the development of the unwebbed foot of the chicken and webbed foot of a duck

Question

Quizplus · Accepted Answer

BMP4 and gremlin are both expressed in the development of the feet in chickens and ducks. However, the difference in their expression patterns contributes to the morphological differences between the species. In ducks, gremlin is expressed throughout the leg, including between the toes, which inhibits BMP4 activity and allows webbing to form. In chickens, gremlin is not expressed between the toes, allowing BMP4 to promote cell death and prevent webbing, leading to the development of unwebbed feet.

In Comparing the Development of the Unwebbed Foot of the Chicken