生肌调节因子在绵羊不同胎儿期心肌和骨骼肌中的表达

本试验旨在探究生肌调节因子（myogenic regulatory factors，MRFs）在绵羊不同胎儿发育时期心肌和骨骼肌组织中的表达情况。选取妊娠60（E60）、70（E70）、80（E80）和90 d（E90）4个不同时期的滩羊胎儿作为研究对象，采集骨骼肌和心肌组织，通过HE和油红染色观察心肌和骨骼肌在胎儿发育过程中发生的组织形态学变化；通过实时荧光定量PCR研究绵羊胎儿发育过程中MRFs在心肌和骨骼肌组织中的表达规律以及同一胎儿期MRFs在心肌和骨骼肌中的表达差异。HE染色结果显示，心肌组织和骨骼肌组织的微观结构差异明显，心肌肌纤维密度大，纵横交错成网状，和骨骼肌相比发育的更加成熟；骨骼肌组织肌纤维密度小，间隙大，E60~E90肌纤维数量逐渐增加，肌纤维束结构清晰分明。油红染色结果显示，心肌和骨骼肌组织在4个时期均未出现被染成红色的脂滴，表明E60~E90两个组织均没有分化出脂肪。实时荧光定量PCR结果显示，E60~E90胎儿心肌组织中MYOG、Myf5和Myf6基因表达量持续降低，但是没有MYOD基因表达；E60~E90骨骼肌组织中MYOD、MYOG和Myf6基因表达量持续上升，其中MYOG基因表达水平最高，Myf5基因的表达发生周期性波动。以上结果表明，E60~E90胎儿骨骼肌正处于快速发育阶段，而心肌组织此时已大致成型。因此，骨骼肌组织中MRFs的表达量远远高于心肌组织，且MYOG基因对于维持骨骼肌的快速发育发挥了重要作用。

Expression of Myogenic Regulatory Factors in Myocardium and Skeletal Muscle at Different Fetal Stages

The topic of this research was to investigate the expression pattern of myogenic regulatory factors (MRFs) in the myocardium and skeletal muscle of sheep at different fetal stages,the fetuses of Tan sheep at 60 (E60),70 (E70),80 (E80) and 90 days (E90) of gestation were selected as the research objects,and the myocardium and skeletal muscle were collected.The histogenesis of myocardium and skeletal muscle during fetal development were observed by HE and oil red staining.The expression patterns of MRFs in myocardium and skeletal muscle during fetal development and the expression differences of MRFs between myocardium and skeletal muscle at the same stage were tested by Real-time quantitative PCR.The results of HE staining showed that the microstructure of myocardium and skeletal muscle was very different,myocardial fibers crisscross into a network with high density,which were more mature;the density of skeletal muscle fibers were low with large gaps,the number of fibers from E60 to E90 increased gradually,and the structure fiber bundles was very clear.The results of oil red staining showed that there were no fat droplets stained red in myocardium and skeletal muscle tissues,which means that these two tissues form E60 to E90 did not have fat differentiation.The results of Real-time quantitative PCR showed that the expression of MYOG,Myf5 and Myf6 genes in myocardium decreased continuously from E60 to E90 day,but there was no MYOD gene expression.The expression of MYOD,MYOG and Myf6 genes in skeletal muscle from E60 to E90 increased gradually,among which the level of MYOG gene was the highest,and the expression of Myf5 gene fluctuated periodically.The above results indicated that the skeletal muscle was at the stage of rapid development from E60 to E90,however,the myocardial tissue had been roughly formed,which led to the expression of MRFs in skeletal muscle tissue was much higher than that in myocardial tissue,and MYOG gene played an important role in maintaining the rapid development of skeletal muscle.