初生与成年牦牛心肌的组织学结构比较

A comparative study on the histological structure of the myocardium between the newborn and the adult yak

为探究牦牛心肌发育过程中组织学结构的变化,采用组织学、组织化学和免疫组织化学方法对初生和成年牦牛心肌的组织学结构、心钠素(ANP)和缝隙连接蛋白43(Cx43)的表达情况进行了观察。结果显示,初生牦牛心肌细胞数量少且细短,闰盘为直线型或V型,心肌细胞间以Ⅲ型胶原纤维为主,Ⅰ型胶原纤维较少;成年牦牛心肌细胞粗长,其数量是初生牦牛的2倍,闰盘呈竹节样吻合或阶梯状,心肌细胞间以Ⅰ型胶原纤维为主。初生和成年牦牛,ANP在心房肌细胞中均表达强烈,且右心房表达量显著高于左心房,心室肌细胞中不表达。ANP在普肯耶纤维中有少量表达。初生牦牛心房肌细胞ANP表达量高于成年牦牛。在心肌细胞膜和胞质内,初生牦牛Cx43表达强于成年牦牛,但在闰盘内,成年牦牛Cx43表达强于初生牦牛。Cx43在初生和成年牦牛的普肯耶纤维中均呈膜阳性。结果提示,初生与成年牦牛相比,成年牦牛的心肌细胞变粗长且数量增多,ANP在心房肌表达减弱,Cx43在闰盘表达更显著,说明成年牦牛较初生牦牛适应循环变化的代偿能力呈进行性减弱;细胞间牢固性增加,有助于实现心肌收缩信号的迅速传导。

In order to explore the histological features of yak myocardium during development,we used histological and immunochemical methods to observe the histological characteristics of newborn and adult yaks. The results showed： in newborn yaks,the number of myocardium was less than in adult yaks,the shape was thinand short,the intercalated discswere straight or V- shaped,the type Ⅲ collagen fibers dominated,and type Ⅰ collagen fibers were scarce between myocardium. In adult yaks,the number of myocardium was twice as many as in newborns. The shape was thick and long,the intercalated discs were bamboo-like or ladder-like and distributed between adjacent myocardium,the type Ⅰ collagen fibers dominated between myocardium. ANP was only expressed in atria myocardium,with expression quantitygreater in the right atrium than in the left atrium,and in newbornsmore than in the adult yak. Less ANP was expressed in Pukinje fibers and the expression of ANP was negative in the left and right ventricular muscle. The expression of Cx43 in myocardial membrane and cytoplasm in newborns weregreater than in the adult yaks,but at the intercalated discs,the adult was greater than the newborn yaks. Cx43 was positive in membranes of Pukinje fibers in newborn and adult yaks. These results indicated that the shape of the myocardium became thicker and longer,the number was increased,ANP expression in atrial muscle was decreased,and Cx43 expression in intercalated discs was more remarkable,the compensatory capacity of adaptation cycle change was progressively reduced; and the intercellular junction was strengthened,that could increase the speed of the impulse conduction among myocardium in the adult yakscompared with newborn yaks.