Silkie the "SHH" gene, called the ZPA Regulatory Sequence (ZRS). This causes ectopic "SHH" expression in the anterior of the developing limb bud, leading to increased tissue growth and digits. While the feet of the Silkie display polydactyly, the wings have the standard tridactyly (three digit) arrangement. The Japanese Silkie initially develops additional digits in the wing as an embryo, but these are lost prior to hatching. The genetic cause behind Silkie polydactyly differs from those that cause polydactyly in the Dorking chicken breed, which is due to ectopic "FGF4" expression in the AER, with ectopic "SHH" a secondary effect. The
A Bird in a Guilty Cage A Bird in a Guilty Cage A Bird in a Guilty Cage is a 1952 "Looney Tunes" animated short featuring Sylvester and Tweety. The title is a pun on the song "A Bird in a Gilded Cage". Sylvester is at a store called Stacy's, where he notices Tweety in the window stand. Going through the package slot, he closes the curtains and climbs up to Tweety's cage, who asks him what he's going to do. After asiding to the audience, "How naive can ya get?", Sylvester replies that they're going to play a game called Sandwich, involving Tweety getting sandwiched