Expression of avian prickle genes during early development and organogenesis.

Chicken homologues of prickle-1 (pk-1) and prickle-2 (pk-2) were isolated to gain insight into the extent of planar cell polarity signaling during avian embryogenesis. Bioinformatics analyses demonstrated homology and showed that pk-1 and pk-2 exhibited conserved synteny with ADAMTS20 and ADAMTS9, GON-related zinc metalloproteases. Expression of pk-1 and pk-2 was established during embryogenesis and early organogenesis, using in situ hybridization and sections of chicken embryos. At early stages, pk-1 was expressed in Hensen's node, primitive streak, ventral neural tube, and foregut. In older embryos, pk-1 transcripts were detected in dorsolateral epithelial somites, dorsomedial lip of dermomyotomes, and differentiating myotomes. Furthermore, pk-1 expression was seen in lateral body folds, limb buds, and ventral metencephalon. pk-2 was expressed in Hensen's node and neural ectoderm at early stages. In older embryos, pk-2 expression was restricted to ventromedial epithelial somites, except in the most recently formed somite pair, and limb bud mesenchyme.