Distribution of fibroblast growth factors (FGFR-1 and -3) and platelet-derived growth factor receptors (PDGFR) in the rat mandibular condyle during growth.
OBJECTIVE
To elucidate the role of the fibroblast growth factors 1 and 3 (FGFR-1, -3) and the platelet derived growth factor (PDGFR) in the growth of the mandibular condylar cartilage in the rat.


METHODS
Institute of Dentistry and Department of Biostatistics, University of Turku, Turku, Finland. The material consisted of 1- to 21-day-old Long-Evans/Turku rats (total of 24 animals, three in each age group).


METHODS
An immunohistological in vivo study combined with histomorphometry and biostatistical analysis.


METHODS
The animals were killed with an overdose of carbon dioxide and thereafter decapitated. Heads were fixed in 4% paraformaldehyde, decalcified in 12.5% ethylenediaminetetraacetic acid, cut sagittally into two halves and sectioned sagittally at 6 microns. In order to detect FGFR-1, -3 and PDGFR the sections were treated with H2O2/methanol (1:100), after which FGFR-1 and PDGFR monoclonal and FGFR-3 polyclonal antibodies were applied. The reaction products were visualized by using the Vectastain ABC Elite Kit using peroxidase substrate kit DAB as substrate. Negative and positive controls were also prepared. The sections were counterstained with hematoxylin.


METHODS
In order to measure the depth of the cell layer labeled with FGF-1, -3 and PDGF receptors, the condylar head was divided into four regions: anterior, superior, posterosuperior and posterior. The measurements were made perpendicular to the articular surface using a computerized image analysis system, the images being acquired by means of a microscope connected to a CCD camera. The mean of five equally distributed measurements of each region was used to indicate the depth of the cell layers secreting the receptors. Regression analysis was used to evaluate the association between the depth of the labeled cell layer in relation to total depth of the condylar head, as a function of age.


RESULTS
Our results show that the depth of the cell layer labeled for FGFR-1, -3 and PDGFR increase significantly as a function of age in the mandibular condylar head of rats.


CONCLUSIONS
Increase in the cell layer labeled for FGFR-1, -3 and PDGFR occurs during the stage when the articular function of the mandibular condyle intensifies. FGFR-1, -3 and PDGFR evidently have an important role in the growth regulation of the condylar cartilage during the most rapid growth period in the rat.
Visnapuu
V
V
Institute of Dentistry, University of Turku, Lemminkäisenkatu 2, FIN-20520 Turku, Finland. vivvis@utu.fi
Peltomäki
T
T
Rönning
O
O
Vahlberg
T
T
Helenius
H
H
D000367:Age Factors; D000818:Animals; D000906:Antibodies; D000911:Antibodies, Monoclonal; D002358:Cartilage, Articular / Q000166:cytology / Q000254:growth & development; D002455:Cell Division; D004396:Coloring Agents; D016220:Fibroblast Growth Factor 1 / Q000032:analysis*; D051518:Fibroblast Growth Factor 3; D005346:Fibroblast Growth Factors / Q000032:analysis*; D007091:Image Processing, Computer-Assisted; D007124:Immunoenzyme Techniques; D007150:Immunohistochemistry; D008335:Mandibular Condyle / Q000166:cytology / Q000254:growth & development*; D010982:Platelet-Derived Growth Factor / Q000032:analysis; D011518:Proto-Oncogene Proteins / Q000032:analysis*; D051381:Rats; D017479:Receptors, Platelet-Derived Growth Factor / Q000032:analysis*; D012044:Regression Analysis
D000906:Antibodies; D000911:Antibodies, Monoclonal; D004396:Coloring Agents; C489199:Fgf3 protein, rat; D051518:Fibroblast Growth Factor 3; D010982:Platelet-Derived Growth Factor; D011518:Proto-Oncogene Proteins; D016220:Fibroblast Growth Factor 1; D005346:Fibroblast Growth Factors; D017479:Receptors, Platelet-Derived Growth Factor