Fracture repair of reptilian dermal bones: can reptiles form secondary cartilage?
AUTOR(ES)
Irwin, C R
RESUMO
The fracture repair of reptilian dermal bones has not previously been reported. Moreover, repair of fractured dermal bones in birds and mammals involves secondary chondrogenesis whereas that of amphibians does not. Therefore an investigation into the repair of fractured reptilian dermal bones could reveal the stage during vertebrate evolution at which the process of secondary chondrogenesis appeared. Experimental incisions were made in the parietal bones of seventeen lizards (3 species) and 2 snakes (1 species). These resulted in a fracture environment of limited vascularity and increased movement--two known stimuli of secondary chondrogenesis in birds and mammals. Re-epithelialisation was rapid and dead bony fragments quickly sequestered. The blood blot was quickly organised into connective tissue, the dural periostea proliferated, osteoblasts differentiated and bony union was effected after 18 days. The width of the fracture gap was the principal variable affecting the chronology of fracture repair. Secondary cartilage was not detected in any specimen, of any species, at any stage of the fracture repair. It therefore appears that the progenitor cells on reptilian dermal bones are not capable of forming secondary cartilage and that this tissue arose comparatively late in vertebrate evolution.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1166524Documentos Relacionados
- Adamantinoma of long bones: clinical, pathological and ultrastructural features.
- Bones: A Study of the Development and Structure of the Vertebrate Skeleton
- Remodelling of bone and bones: growth of normal and transplanted caudal vertebrae.
- Remodelling of bone and bones: effects of altered mechanical stress on caudal vertebrae.
- Normal Skeletal Development of Mice Lacking Matrilin 1: Redundant Function of Matrilins in Cartilage?