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
Build-A-Bird real life birds that fit your selections. What happened next in the game involved educational material about your bird's range and habitat. The visual representations of the birds, their body parts and the bird habitats were in colour and vivid for the time but lacked animation. Build-A-Bird Build-A-Bird (1986 or earlier) was educational software for the Unisys ICON II public school computer. It may have appeared on the ICON I or Unisys ICON III. Build-A-Bird was designed and developed by Ergonomics Lab, University of Toronto. Gameplay revolved around creating a bird by choosing from a selection of different body parts