Send to

Choose Destination
See comment in PubMed Commons below
J Anat. 1986 Jun;146:53-64.

Fracture repair of reptilian dermal bones: can reptiles form secondary cartilage?

Author information

  • 1Department of Anatomy, Queen's University of Belfast.


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.

[PubMed - indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for PubMed Central
    Loading ...
    Write to the Help Desk