Objective      To determine the effect of lipopolysaccharides (LPS) on bone development and mineralization of mice using metatarsal and tibia culture.        Methods      Metatarsals and tibias of embryonic mice at E18.5 were distracted

and divided to blank group and LPS group which was treated with 10 μg/mL LPS. Images of metatarsals and tibias on day 1 and day 7 were obtained to measure the total length and the calcified zone length using Image Pro Plus software. Then the growth rate of total length (TL-rate) and calcified zone (CZ-rate) and the proportion of the calcified zone in the total length (CZ%) were calculated. After 7-day culture

the tibias were embedded in paraffin. Safranin-O and fast green staining was used to measure the length of hypertrophic zone. Immunohistochemical staining for collagen Ⅱ (ColⅡ) and collagen Ⅹ (ColⅩ) was carried out to observe the differentiation of chondrocytes. TUNEL staining was used to observe the apoptosis of chondrocytes.       Results      Measurement data from Image Pro Plus software showed that both TL-rate and CZ-rate of the metatarsals and tibias were lower in the LPS group than in blank group (metatarsal TL-rate P=0.025; metatarsal CZ-rate P=0.019; tibia TL-rate P=0.010; tibia CZ-rate P=0.024). Safranin-O and fast green staining and bone histomorphometry results showed that the hypertrophic zone of the LPS group was obviously shorter than that of the blank group (P0.001). Immunohistochemical results showed that the expressions of ColⅡand ColⅩ were significantly decreased in the LPS group compared with the blank group. TUNEL staining found more apoptosis in the LPS group.        Conclusion      LPS inhibits the embryonic bone development and mineralization through inhibiting the growth of hypertrophic zone and differentiation of the chondrocytes and promoting the apoptosis of chondrocytes.