Prenatal development of the composite occipito‐atlanto‐axial synovial joint cavity in the dog

摘要

AbstractIn the dog, the synovial cavities of the atlanto‐occipital and atlanto‐axial joints communicated to form a single large composite joint cavity. The prenatal development of this composite occipito‐atlanto‐axial joint cavity was studied by examining 26 serially sectioned dog embryos and fetuses that ranged in size from 19 to 68 mm crown‐rump length, and were between 30 and 42 days of gestational age. In the composite occipito‐atlanto‐axial joint, trilaminar interzones developed at 19–22 mm (30–31 days), joint cavities opened at 27–32 mm (33–34 days), and the atlanto‐occipital and atlanto‐axial cavities first commun