Quantitative evaluation of postnatal bone growth in the auditory ossicles of the dog.

The postnatal bone growth (appositional and internal) in the auditory ossicles and in the tibia of three mongrel dogs was studied by means of tetracycline and alizarin labeling. The appositional growth is characterized by an increase in the external dimensions of the auditory ossicles within the first month of postnatal life. No trace of bone deposition was found after this period of time. The patterns of internal growth are: 1) the rate of primary osteon formation shows the same value in the incus and malleus; 2) these values are always less than those in the primary osteons of the diaphysis of the tibia of the same dog; 3) the time required for the formation of these osteons in the auditory ossicles, like in the other parts of the skeleton, increases significantly with age.