Fig. 5

Chondrogenic differentiation. a Bright field view. All of the groups exhibited chondrogenic differentiation. b H&E staining (first row) demonstrated that cultured cartilage cells are prominently increased in the 2 N group in the absence of necrosis or apoptosis. However, cartilage cells are decreased and substituted for necrotic cells and apoptosis in the 4R and 6R groups. Alcian blue staining (second row) likewise demonstrated that cultured cartilage cells declined remarkably as the weeks after exposure to radiation progressed. Immunohistochemistry for type II collagen (third row) demonstrated positivity for cytoplasmic localization of the cultured cartilage cells in the 2 N group. Viable cartilage cells are markedly reduced and replaced with necrotic cells with negative collagen type II antibody expression in the 4R and 6R groups. c Sulfated glycosaminoglycan (sGAG) assay. The level of sGAG was significantly lower in the 6R group than in the 6 N group (^* p < 0.05). d RT-PCR for aggrecan and type II collagen did not reveal any statistically significant differences