成年大鼠下颌功能性前伸后翼外肌的超微结构改变

Ultrastructural characteristics of lateral pterygoid muscle after functional mandibular protrusion in adult rats

目的 观察成年大鼠下颌功能性前伸后翼外肌的超微结构变化.方法 成年雄性Sprague-Dawley大鼠40只,随机分为4个实验组和4个对照组,每组5只.实验组大鼠配戴固定的前伸下颌矫治器,对照组不配戴矫治器.分别于下颌前伸3、7、14、28 d处死实验组和对照组大鼠.取大鼠左右侧的翼外肌,制作电镜标本,透射电镜下观察成年大鼠翼外肌的超微结构变化.结果 在实验组大鼠翼外肌细胞内,下颌前伸3 d时,部分肌丝溶解断裂;下颌前伸7 d和14 d时,肌丝方向紊乱,肌小节宽度不规则;下颌前伸28 d时,局部仍可见肌丝方向紊乱和肌小节宽度不规则.下颌前伸3、7、14 d时实验组大鼠翼外肌细胞肌膜下及肌丝间线粒体增多,形态改变.下颌前伸28 d时,线粒体数量和形态基本正常.下颌前伸14 d时,在实验组大鼠翼外肌细胞内,终板内的神经递质较多.结论 成年大鼠下颌功能性前伸后翼外肌细胞的结构发生了改变.

Objective To investigate the ultrastructural characteristics of lateral pterygoid muscle after functional mandibular protrusion in adult rats. Methods Forty adult male Sprague-Dawley rats were divided into four experimental groups and four control groups, each group had 5 rats.The experimental groups were fitted with fixed bite-jumping devices that protruded the mandible. The control groups did not wear the devices. The animals were sacrificed on days 3, 7, 14, 28 days after experimental mandibular protrusion . The left and right lateral pterygoid muscle were dissected and observed under transmission electronic microscope. Results The myofilaments of experimental lateral pterygoid musle were dissolved and ruptured on days 3. The myofilaments interlaced and the sarcomeres did not arranged by rule in the experimental groups on days 7and 14. On days 28, The direction of a little myofilaments were different. The amount of subsarcolemmal and intermyofibrilar mitochondria of lateral pterygoid muscle was increased and the shape were changed on days 3,7, 14.The amount and shape of mitochondria were normal on day 28 after experimental mandibular protrusion. The excitatory transmitter in the end plate of lateral pterygoid muscle cells increased on 14days after functional mandibular protrusion. Conclusions The lateral pterygoid muscle showed ultrastructural alterations after experimental mandibular protrusion in adult rats.