Histomorphological analysis of human cranial bones: Relationship to aging

Aging induces alterations in bone microarchitecture, including bone function. This study aimed to identify histological changes in the components of cranial bones of the human skull and to investigate their relationship with aging. In this study, sixty-four fresh cranial remains were examined with an age range of 43-90 years, the crania being randomly selected to investigate the microstructure of the frontal, temporal, parietal, and occipital bones, which were stained using picrosirius red. Our results observed similar histological changes in the frontal, temporal, parietal, and occipital bones. Results of the histomorphological analyses demonstrated that there was an age-related gradual increase in the number of osteons. A distinct increase in the number of osteons in the cortical bone was found, particularly over 60 years. As age increased, the area of the circumferential lamellae adjacent to the periosteum also tended to diminish. A greater lamellar area was found in association with younger individuals, the area declining with age. In some samples from individuals older than 80 years, the outer circumferential lamellae were no longer visible. In addition, there was an association between cortical porosity and numbers, and the enlargement of porosity and age. The size of the pores in the cancellous bone tended to increase as well. This histomorphological study increases the comprehension regarding the relationship between the aging process and the structure of the human cranial bone in adults, and the results can be regarded as alternative data in the determination of age in humans.