Immunohistochemical localization of elastin, fibrillins and microfibril-associated glycoprotein-1 in the developing periodontal ligament of the rat molar.
OBJECTIVE
Elastic system fibers are a major component of the periodontal ligament, but little information is available about their detailed composition or the mechanism of elastogenesis in the developing periodontal ligament. The purpose of this study was to investigate immunolocalization of elastin, fibrillins and microfibril-associated glycoprotein-1 (MAGP-1) in the developing periodontal ligament of the rat molar.


METHODS
Frozen sections of demineralized as well as non-demineralized periodontal ligament of Wistar rats of various ages from 19 days to 7 weeks were incubated with anti-elastin, anti-fibrillin-1 and -2 and anti-MAGP-1 antibodies followed by peroxidase-conjugated secondary antibodies. After incubation with diaminobenzidine solution, immunoreaction products were observed with a light microscope.


RESULTS
In the developing periodontal ligament of 19-day-old rats, fibers immunopositive to elastin were not present, but fibers positively stained for fibrillin-2 and MAGP-1 were widely distributed throughout the ligament. The latter fibers were arranged in the apico-occlusal direction along with blood vessels. In 3-week-old rats, fibers stained for elastin were observed for the first time in the apical region of the ligament. The number and distribution pattern of these elastin-positive fibers was basically the same as those in rats aged 5 and 7 weeks. In contrast, fibrillin-2- and MAGP-1-positive fibers were more extensively distributed in the ligament, and their pattern of distribution was comparable to that of reported oxytalan fibers. Fibrillin-1 was, however, not detected either in demineralized sections or in non-demineralized sections, indicating its absence in periodontal ligament.


CONCLUSIONS
Elastin expressed in the periodontal ligament assembled into elaunin fibers in the vicinity of blood vessels. Both fibrillin-2 and MAGP-1 are structural components not only of the elastin-associated microfibrils but also of elastin-free microfibrils, with possible roles in elastogenesis and in periodontal ligament homeostasis.
Sugawara
Y
Y
Department of Ultrastructural Science, Tokyo Dental College, Chiba, Japan.
Sawada
T
T
Inoue
S
S
Shibayama
K
K
Yanagisawa
T
T
D000818:Animals; D003285:Contractile Proteins / Q000032:analysis*; D004547:Elastic Tissue / Q000254:growth & development*; D004549:Elastin / Q000032:analysis*; D016326:Extracellular Matrix Proteins / Q000032:analysis*; D000071838:Fibrillin-1; D000071840:Fibrillin-2; D000071837:Fibrillins; D007150:Immunohistochemistry; D008297:Male; D008840:Microfilament Proteins / Q000032:analysis*; D008963:Molar / Q000033:anatomy & histology*; D009805:Odontogenesis / Q000502:physiology; D010513:Periodontal Ligament / Q000098:blood supply / Q000254:growth & development*; D000072260:RNA Splicing Factors; D051381:Rats; D017208:Rats, Wistar; D019228:Tooth Crown / Q000254:growth & development; D014078:Tooth Eruption / Q000502:physiology; D014092:Tooth Root / Q000254:growth & development; D054392:Adipokines
D003285:Contractile Proteins; D004549:Elastin; D016326:Extracellular Matrix Proteins; D000071838:Fibrillin-1; D000071840:Fibrillin-2; D000071837:Fibrillins; D008840:Microfilament Proteins; D000072260:RNA Splicing Factors; C000605725:Fbn1 protein, rat; D054392:Adipokines; C000605729:Fbn2 protein, rat; C016598:microfibrillar protein; C437744:oxytalan