ABSTRACT
Objective: To observe the effect of type 1 bone morphogenetic protein (BMP) receptor activin A receptor type 1 ( ACVRl) on the morphology, proliferation and differentiation of the mandibular condylar cartilage (MCC) cells in the postnatal mice, and to provide the reference for the study on etiology and treatment of MCC-related disease. Methods: The C57BL/6J mouse model of conditional deletion of ACVRl gene was constructed by using the Cre-LoxP system. The female and male mice with Acvrl1" ; RS/RS and Acvrl ; Osterix (+)/( ) genotypes were paired off with each other; the offspring Osterix-Cre ( + ); Acvrl'∗ ; RS/+ genotype mice were selected as experiment group, and the Osterix-Cre ( + ); Acvrl1" ; RS/+ mice were selected as control group. The newborn (n-3). postnatal day 21 (n=4) and PN42 (n=5) male mice were selected. X-gal staining was used to detect the expressions of Osterix-Cre in MCC tissue of the mice in two groups. micro-CT was used to detect the condylar widths and condylar head lengths of mandible of the mice in two groups. HE and Toluidine blue staining were used to analyze the morphology of MCC cells and the thickness of caritilage in each layer of MCC tissue of the mice in two groups, immunohistochemical (1HC) staining was used to detect the number of proliferating cell nuclear antigen (PCNA)-positive cells and the level of type X collagen in MCC tissue of the mice in two groups. Results: The X-gal staining and 1HC results showed that the mouse model of ACVRl gene conditional deletion was successfully constructed. At PN21. compared with control group, the condylar width and the condylar head length of mandible of the mice in experiment group were significantly shortened ( P<0. 05); the morphology of the MCC cells of the mice in two groups had no significant difference. Compared with control group, the number of PCNA-positive cells in the MCC cells of hypertrophic chondrocyte zone (Hy) and chondroblastic zone (Ch) and single Hy of the mice in experiment group were significantly increased ( P<0. 05 or P-<0. 01). At PN42. compared with control group, the shape of parts of the mandibular condylar cartilage cells of the mice in experiment group was abnormal, and the arrangement of some condylar chondrocytes was disordered, the cell thickness of the Ar. Pr and Ch in intermediate part and Hy in anterior part of the condylar cartilage of the mice in experiment group were significantly increased ( P<0. 05 or P<.0. 01); compared with control group, the number of PCNA-positive cells in each zone and the level of type X collagen in Ch of MCC tissue of the mice in experiment group were incresed. Conclusion: ACVRl affects the morphology of MCC cells and structure of MCC tissue by inhibiting the proliferation of MCC cells and the differentiation of chondroblasts into hypertrophic chondrocytes.
ABSTRACT
Objective:To study the expressions of cell polarity related proteins CDC42 and PAR3 during tooth germ development in the mice,and to discuss their possible roles during tooth development in the mice.Methods:The whole heads were obtained from the mouse embryo on the days 13.5,14.5,16.5 and 18.5 (E13.5,E14.5,E16.5 and E18.5) and the mice on the postnatal days 1 (PN1) and 5 (PN5).The tissues were fixed in paraformaldehyde,decalcified,dehydrated,embedded in paraffin,and sectioned.The histology of tooth germ was observed by HE staining.The expressions of CDC42 and PAR3 during tooth germ development were detected by immunohistochemistry staining.Results:The HE staining results showed that E13.5,E14.5,E16.5 and E18.5were the bud stage,the cap stage,the early and the late bell stage of tooth germ development,respectively;the tooth germ of PN1 mice showed the matured odontoblasts and ameloblasts;the tooth germ of PN5 mice showed the completed tooth crown development.The immunohistochemistry staining results showed that CDC42 expressed in the tooth germ of the mice at E13.5,E14.5 and E16.5;the CDC42 expression at E 18.5 was reduced compared with E13.5,E14.5 and E16.5;CDC42 mainly expressed in the odontoblasts and ameloblasts of the tooth germ of the mice at PN1 and PN5;PAR3 weakly expressed in the tooth germ of the mice at E13.5 and E14.5,and it was increased at E16.5 and E18.5.At PN1 and PN5,the expressions of PAR3 were decreased compared with E18.5.Conclusion:CDC42 and PAR3 partieipat in the mouse tooth development;during the early stage of tooth germ development,they may be involved in the proliferation and migration of mouse dental germ;during the late stage,CD42 and PAR3 may be involved in the differentiation of the odontoblasts and the ameloblasts,especially in the establishment and maintenance of cell polarity.