The perichondrial ring as a reservoir for precartilaginous cells. In vivo model in young chicks' epiphysis

Background: The purpose of this study is to illustrate the routes of migration of precartilaginous cells from the perichondrial ring of LaCroix, as a potential reservoir for growth-plate germ cells. Methods: Chondrocytes derived from the ring of LaCroix of young chicks' proximal tibia were cultured in vitro and transfected with adenovirus vector containing the gene encoding for Escherichia coli (beta)-galactosidase (lacZ) gene, which allows assessment of the migratory routes of these cells. The lacZ- transfected cells were injected back into the perichondrial ring of LaCroix of young chicks' proximal tibias. Four weeks later the migration root was assessed microscopically. Results: Injection of cells derived from the ring of LaCroix of neonate chicks, transfected in culture with adenoviruses containing LacZ reporter gene, allows the assessment of migratory potential of these cells. Stained cells were found at the outer layer of the epiphysis, particularly in areas adjacent to the perichondrial ring. Further longitudinal histopathological studies along the bone axis demonstrated a condensed layer of the stained cells arranged horizontally along parts of the physis. Conclusion: The perichondrial ring of LaCroix represents a potential reservoir of growth-plate germ cells in young chicks.