| The incidence of craniosynostosis is 1/2500 and the etiology is unknown yet. The clinical diagnosis of craniosynostosis includes a vari-ety of disorders characterized by the inadenquancy of the calvaria to accommodate the growing brain. These disorders occur either as an i-solated condition, in association with metabolic abnormalities, or as part of a constellation of abnormalities in familial craniosynostosis syn-dromes.Cranial suture in rats provide an excellent model to study this subject. The purpose of this experiment was to investigate the expres-sion of bFGF before, during and after normal suture fusion in the rat model by HE staining and SABC immunohistochemical staining tech-niques in order to provide theoretic basis for future reseach of the eti-ology of craniosynosis.Materials and MethodsSixty Sprague - Dawley rats were used in this study. Postnatal rat of 1,6,12,17 and 22,35 days old. PF and SAG suture were harvestd at each following time point. No surgical or biochemical manipulation has been performed. The section were dehydrated ingraded ethanol so-lutions, five - micrometer serial coronal sections were cut for immuno-localization of bFGF. Observe the result of immunohistochemical stai-ning of bFGF.ResultHistologically, posterior frontal sutural fusion started on day 12 and was completed by 22. The sagittal suture remained patent at all time points.At day 1, minimal immunostaning for bFGF in the cranial sutures of animals was noted in the sutural connective tissue and a few osteo-blast at the sutural margin of both types of sutures.At day 6, periosteal cell adjacent to the dura increased markedly in the PF suture.At day 12, staining of the PF sutural connective tissue incresed markedly with numerous, large, intensely bFGF - positive osteoblast located on the dural surface of the suture.At day 17, the endocranial surface of this suture was fused. In-tense staining of the sutural fibroblasts and the underlying dure mater was also noted.At day 22, vitually the entire suture was fused with only a few remnants of sutural connective tissue.At day 35, the suture was completely fused, only minimally reac-tive to bFGF and minimal staining was noted as the SAG suture, mini-mal staining for bFGF was noted at all time points examined.In the PF suture of 1,6,12,17,22 day - old animals, moderate immunoreactivity for FGF - R2.Discussion1. Physiological development of cranial sutureCranial suture not only maintains the continuity of calvaria, but also provides space for the growth of the adjacant bones. During it's development, a presumptive suture becomes a definitive suture with interdigitations, and patent suture eventually close with bony bridg-ing. Man is metopic suture fuses at 2 years old, other sutures fuse be-tween 20 and 30 years old.Moss first set up an animal model for studying the problem of cra-nial suture in 1960. He found PF suture of SD rat underwent fusion be-tween 12 and 22 days, while other sutures kept patent, which is analogious to the relation of man's metopic with other sutures. So I use SD rat as the model in my experiment.2. Physiological action of bFGFResearch on the GFs is one of frontiers topic of biology. BFGF is a multipeptide regulator. It can stimulate the multiplication of chon-drocyte and ECM formation.3. BFGF, FGF - R2 and suture developmentIn this experiment, the change of immunostaining expression of bFGF in PF suture is obviously different from that in SAG suture. When the suture fuses actively; the immunostaining is intense; when the fusion is complete, or the suture is still patent, the staining is weak. That indicated that the degree of immunostaining change simul-taneously with the suture fusion. Suggesting bFGF play an important role in the growth , development and fusion of PF suture of the SD rat.FGF - R2 shows definitely different staining pattern.During the active fusion of PF suture, the expression of FGF -R2 is weak; while in the patent sagittal suture, the expression is s... |
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