Histogenesis of the nasal bones and paranasal sinuses: clarification of development patterns and tissue origin

Reparative processes repeat the stages of embryonic histogenesis. Skull bones that underwent intramembranous osteogenesis during embryonic development replicate the pattern of «non-cartilaginous » osteogenesis during reparation (and therefore do not restore their histoarchitecture after injury), while secondary bones participate in the formation of soft and hard calluses. Incorrect determination of the type of bone osteogenesis leads to further errors in the planning and development of rhinosurgical techniques and procedures performed on the facial skull structures. Objective. To determine the type of osteogenesis of the facial bones and classify them according to their developmental pattern. Material and methods. A histological examination of the mid face of 13 human fetuses, including 7 males and 6 females, was performed between the 13th and 19th weeks of gestation. Light microscopy was used to identify the type of osteogenesis. Frontal, nasal, maxillary, palatine, ethmoid bones, inferior turbinates, vomer and sphenoid bones were examined. Results. Bones developing according to the intramembranous type of osteogenesis were identified: frontal, nasal, maxillary and palatine bones. These bones have weak regenerative and remodeling capacities. Bones undergoing the enchondral type of osteogenesis include the ethmoid bone, inferior turbinates and vomer. The bulk of the sphenoid bone underwent enchondral ossification, and the wings of the sphenoid bone developed without the cartilaginous stage. Conclusion. The study of bone histogenesis, which comprise the airway system of the nose and paranasal sinuses, in human fetuses provides a clear understanding of the type of osteogenesis. The embryonic origin of the tissue determines the specific characteristics of bone in the postembryonic period. The reparative and remodeling capacities of primary and secondary bones differ radically, which must be considered during surgical interventions on the skeletal structures of the skull.