Differential distribution of microtubules in immature osteocytes in vivo

Objectives: The transition from osteoblasts to osteocytes is associated with dramatic changes in the cytoskeleton. We previously showed that the formation of osteoblast cell processes in 3D culture is microtubule dependent. However, the distribution of microtubules during the transition from osteoblasts to osteocytes in vivo is unknown. In this study, we investigated the distribution of microtubules in osteocytes in vivo. Methods: We observed the microtubules in osteocytes in chick embryonic calvaria via fluorescence staining of microtubules and confocal laser scanning microscopy. Results: Microtubules were observed throughout the cytoplasm in all examined osteoblasts. In immature osteocytes, several cell processes contained microtubules, whereas in mature osteocytes, microtubules were localized only in the cell body. Conclusion: These results suggest that the early arrangement of microtubules may be correlated with the initial development of osteocyte processes.