Prenatal ossification in rabbits as indicative of fetal maturity

During the prenatal period of development of the rabbit skeleton (days 21-30) the successive phases of fetal maturity can be distinguished by reference to the progress of ossification, particularly in the distal limbs and sternum. In the present study absent or incomplete ossification of sternebra 5 occurred in 8% of term fetuses. The incidence of anomalies of prenatal ossification of the axial skeleton was 1.9%. The relevance of delayed and disturbed ossification with regard to teratological tests is discussed.