The distribution and fate of the adventitious cartilage in the skull of the eastern rosella, Platycerus eximius (Aves : Psittaciformes)

Abstract

A histological study has been made of the articulations of the membrane bones with other elements of the skeleton in the skull of nestling and juvenile eastern rosellas. The majority of the articulations are diarthrodial. Adventitious cartilage is present on the membrane bones of the nestlings and serves as an embryonic articular cartilage. Fibrocartilage replaces the adventitious cartilage in the juveniles and serves as the adult articular cartilage. The structure and function of these cartilages are discussed and it is suggested that mechanical stimulation is responsible both for the formation of the adventitious cartilage and for its replacement by fibrocartilage.