Figure 5.

Effects of severe hypoxia on the morphology of human periodontal ligament fibroblasts (HPLFs). (A–D) Inverted microscopy was performed at various time points. (A) At 12 h post-cultivation the cells were in good condition, flat fusiform or dendroid in shape and were arranged in a monolayer with normal cell spacing; original magnification, ×100. (B) At 24 h post-cultivation, the cells grew vigorously with full cell bodies, clear nuclei and two or three fine cytoplasmic processes; original magnification, ×100. (C) At 48 h post-cultivation, the cells became contracted and sparse, their cytoplasmic processes were reduced and their cytoplasms became vesiculated; original magnification, ×100. (D) At 72 h post-cultivation, the cells were in a worse condition and sections disassembled and disappeared; original magnification, ×100. (E–J) Transmission electron microscope (TEM) was also performed at various time points. At 12 h post-cultivation revealed that the organelles remained normal in cells, and the cytoplasm of the HPLFs contained numerous mitochondria and rough endoplasmic reticula (RER); original magnification, ×6200. (F) At 24 h post-cultivation showed a marked increase in the number of mitochondria and RER; original magnification, ×6200. (G) At 48 h post-cultivation, the number of mitochondria and RER decreased. The mitochondria increased in size, the cristae appeared to be vague and RER structural disorder was observed; original magnification, ×6200. (H) At 72 h post-cultivation, degeneration occurred, and the number of mitochondria and RER further decreased with the broken membrane structure. Mitochondrial cristae were disassembled, vacuolar degeneration occurred and particles of the RER were reduced with increasing number of lysosomes; original magnification, ×6200. (I) At 24 h post-cultivation, the cells had numerous cytoplasmic processes; original magnification, ×5800. (J) At 72 h post-cultivation, the cell had few cytoplasmic processes; original magnification, ×6200.