Age and sexually dimorphic changes in costal cartilages. A preliminary microscopic study.

This study reports changes in costal cartilages that appear at the microscopic level throughout life, especially during the ossification process. The work builds on the results of our previous X-ray study, which confirmed the presence of two sexually dimorphic ossification patterns. This led to questions about the existence of additional sex-specific patterns that relate to the ossification process in costal cartilages. Samples of costal cartilages and adjacent parts of the bones were obtained from the autopsies of 17 corpses. The age range among the cadavers varied greatly, from a newborn baby to 91 years of age. Sections of costal cartilage were routinely processed and stained. Alkaline phosphatase activity was detected using histochemical methods. Collagens type II and X were detected immunohistochemically by monoclonal antibodies. The results of our study show that ossification of costal cartilages can take place in the form of two individual processes, localization and time-separate. Endochondral ossifications in the region of the costochondral zone appear in the first decade, and they correspond to ossifications detected by X-ray in the second decade. The location of sex-specific ossifications is determined by the penetration of cartilage canals into the metaphysial part of the rib. Endochondral intramembranous ossifications in the reserve zone appear after the third decade. These types of ossifications correspond to central globular ossifications detected by X-ray, and they are not sexually dimorphic. They can serve for accurate estimation of age.