兔窦房结组织急性损伤后细胞形态结构改变的动态观察

目的探讨用甲醛湿敷致兔窦房结组织急性损伤后窦房结细胞形态学的动态变化规律.方法将60只日本大耳白兔随机分组,用20%甲醛湿敷窦房结区建立窦房结急性受损术后2 h、1、2、3周及4周(每组10只)实验组模型,对照组与术后2 h组于湿敷后2 h、其余各组分别于相应时间点切取窦房结组织留取标本;观察用TUNEL法检测窦房结细胞凋亡情况.结果光镜下,各实验组均有不同程度的窦房结细胞损伤,主要表现为细胞明显肿胀、粒细胞浸润、细胞坏死及胶原纤维增生等病变.电镜下各实验组细胞超微结构病变亦明显,主要表现在线粒体肿胀及嵴变短、紊乱或断裂甚至消失;内质网则广泛解体、离断;核膜极不规整,核仁裂解,染色质边聚肌丝模糊,片状溶解或坏死.对照组兔窦房结均未见明显的细胞凋亡.实验组兔窦房结均可见不同程度的细胞凋亡,与对照组相比凋亡率均有显著性差异(P＜0.01),但实验组之间凋亡率无统计学意义(P＞0.05).结论用甲醛湿敷法损伤窦房结组织不仅导致窦房结细胞不可逆性损伤,而且可诱发窦房结细胞凋亡.

Dynamic observation of morphologic change of sinoatrial node cells of rabbits after acute damages

Objective To explore the regularity of dynamic morphologic changes of the sinoatrial node (SAN) cells of rabbits after the constitution was damaged by formaldehyde wet dressing. Methods Sixty rabbits were randomly divided into 6 groups (n=10 in each group): the control group and 5 experimental groups observed at 2 h, 1, 2, 3, and 4 weeks respectively after the operation. The SAN constitution of rabbits was damaged by 20% formaldehyde wet dressing. The constitutions of SAN were cut quickly at 2 h after wet dressing in the control group and at the corresponding time points in other experimental groups respectively. The specimens were made for light microscopical and electron microscopical observations. The apoptosis of SAN cells was detected by TUNEL method. Results Compared with those in the control group, SAN cells in all experimental groups were damaged at various degrees observed by light microscopy and electron microscopy. Distinct cell tumefaction, soak of grain cells, cytoclasis, hyperplasia of collagen fibers, and other pathological changes were detected. Electron microscopical observation showed distinct pathological changes of the super-micro construction of cells. Apoptosis was not detected in the control group, but various degrees of apoptosis in all experiment groups. The apoptotic rates in all experimental groups were significant as compared with that in the control group (P<0.01), but these in all experimental groups were not statistically significant. Conclusion Formaldehyde wet dressing method can not only lead to irreversible damage of the SAN cells but evoke the apoptosis of SAN cells as well.