Distinct expression of APO-1/Fas and caspase-8 in the human growth plate.

Chondrocytes in the growth plate undergo a characteristic sequel of differentiation processes, finally leading in their death by apoptosis. The mechanisms that mediate these remarkable biological phenomenon are still widely unknown. For this study, growth plates from five resected polydactylic infantile fingers were taken and immunostained for APO-1 and Caspase-8, two apoptosis-mediating proteins. The expression of both proteins was examined in the resting zone, proliferating zone, and hypertrophic zone, representing the maturation stages of the growth plate. Positive cells for APO-1 and Caspase-8 were found in all zones of the physis with a significant increase from the resting to the hypertrophic zone (from 17.4% to 33.067% for APO-1 and from 13.17% to 28.22% for Caspase-8). Our findings suggest that both APO-1 and Caspase-8 are involved in chondrocyte development in the growth plate, predominantly near to the closure area.