Developmental ossification sequences of the appendicular and axial skeleton in Kuttanad duck embryos (Anas platyrhynchos domesticus)

The processes of ossification sequences are poorly investigated for birds in general, even for domestic and experimental species and when it comes to the waterfowl it is almost negligible. Such sequences constitute a rich source of data on character evolution, and may even provide phylogenetic information. A pre-hatch developmental study on ossification sequences of axial and appendicular skeletal system in Kuttanad duck embryos was undertaken using 78 viable embryos. From day 3 to day 7 of incubation no ossification densities were seen both by alizarin red staining and computerized radiography. The first indication of ossification as small ossification centers in skull bones, clavicle, scapula, humerus, radius and ulna in forelimb and ilium, pubis femur and fibula in hind limb were observed on the 9th day of incubation. The ossification of the body of the ribs started at the 11th day of incubation towards the proximal extremity. On day 13th the ossification process of vertebrae was started from cervical end. The variation in appearance of the ossification centers in different bones at different stages of incubation period suggests relative importance of phylogeny to the sequences.