Skeletal Analysis and Characterization of Gene Expression Related to Pattern Formation in Developing Limbs of Japanese Silkie Fowl

Abstract

The Japanese Silkie (Ukokkei) is a breed of domestic fowl with several unique characteristics. Skeletal analysis revealed that an extra cartilaginous digit was apparent transiently in the wing bud of Japanese Silkie embryos between stages 32 and 36. In contrast, an extra digit of the leg resembled digit 2 in terms of its skeletal elements. Whole-mount in situ hybridization analysis revealed that Shh, Bmp-2, and Hoxd-13 genes are ex- pressed in the presumptive region of the extra digit in the leg buds at stage 26. Expression of Shh and Hoxd-13 was also apparent in the anterior region, including the presumptive area of the extra digit, in the developing wing bud of Japanese Silkie embryos. The Japanese Silkie fowl thus warrants further investigation as a potential model animal for the study of limb development.