Keywords : Double staining
Iraqi Journal of Veterinary Sciences,
Quail is an essential model in avian research because of economic importance in poultry industries around the world. Furthermore, its use in the experimental embryology research field. Therefore, this study aimed to identify the onset of chondrification and ossification of the wing bones also to summarize the main histological sequences related to the formation of the humerus in Japanese quail. Six embryos were taken every 24 hrs from 3-16 days of incubation. Three embryos were prepared and stained with Alcian blue and Alizarin red for cartilage and bone, respectively. The other three embryos have been processed for histological examination. The Macroscopical findings showed that the humerus, radius, ulna, coracoid, scapula, third, and fourth metacarpals were chondrified on 5th day. However, first signs of ossification were observed in the humerus, radius, and ulna on 8th day. While the minor digit remained none ossified at prehatching. The microscopical stages of developing humerus associated with the limb bud, apical ectodermal ridge formation, and chondrocyte differentiation on 3rd, 4th, and 5th day, respectively. The cartilage template of the humerus was established on 6th day. The diaphysis and epiphyses of the humerus were formed on 7th and 8th day, correspondingly. The periosteal-bone collar was formed on 8th day, and vascularization of chondroepiphysis has occurred on 9th day. There was a difference in the timing of chondrification and ossification in the forelimb skeleton and humerus developed by the endochondral mechanism. The obtained results should be considered in teratological and molecular studies in skeletogenesis.