Distribution of actin bundles in periodontal ligament of rat lower incisor.
The overall distribution of actin bundles in fibroblasts in the periodontal ligament (PDL) was examined in continuously growing incisors of the rat by confocal laser and thin-section electron microscopy to better understand the functional roles of PDL in mechanical support of the tooth and the mechanism of tooth eruption. The PDL around the incisor was divided mainly into two parts: the superior (non-enamel side of the tooth) and inferior (enamel side) parts. In the superior part, elongated fibroblasts ran obliquely near the alveolar bone and shifted direction nearly parallel to the tooth as they approached the tooth. Long and thin bundles of actin filaments were observed running along the long axis of the cells. In the inferior part, flattened cells were densely populated in the narrow space between the enamel epithelium and venous plexus with their long axis parallel to the tooth, and contained relatively thick actin bundles running parallel to the cell axis. Thus, different distribution patterns of fibroblasts and their actin bundles were recognized in different parts of the PDL. These observations suggest that different parts of the PDL of the rat lower incisor may have different functional significances such as force generation of tooth eruption and mechanical resistance to occlusal pressure and continuous growth.
Kobayashi
K
K
Department of Anatomy, Gunma University School of Medicine, Japan.
Ishikawa
H
H
D000199:Actins / Q000378:metabolism*; D000818:Animals; D005347:Fibroblasts / Q000378:metabolism; D006651:Histocytochemistry; D007180:Incisor; D007382:Intermediate Filaments / Q000378:metabolism*; D008297:Male; D018613:Microscopy, Confocal; D010513:Periodontal Ligament / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D014078:Tooth Eruption
D000199:Actins