实验性糖尿病诱导大鼠胸腺细胞凋亡的电镜观察

Ultrastructural study on rat thymocyte apoptosis induced by experimental diabetes

目的 探讨糖尿病诱导大鼠胸腺细胞凋亡的形态学变化 ,从而了解其引起胸腺萎缩的可能机制。方法采用四氧嘧啶诱导复制的大鼠实验性糖尿病动物模型 ,在电镜下观察了糖尿病大鼠胸腺细胞凋亡的形态学变化。结果 在糖尿病大鼠胸腺皮质中发现了大量凋亡的胸腺细胞 ,主要表现为细胞皱缩变小 ,表面形成许多皱突 ,似发泡状 ;细胞质浓缩 ,电子密度增强 ;线粒体肿胀 ,嵴减少与紊乱 ;空泡化细胞核染色质固缩边聚 ,核变成花瓣状、黑环状与黑洞状 ,核与细胞发生裂解形成凋亡小体 ,被巨噬细胞和上皮细胞吞噬清除。此外 ,在凋亡细胞与小体的周围还聚集着许多浆细胞。结论 实验性糖尿病可诱导大鼠胸腺细胞发生大量凋亡 。

Objective To study the morphologic changes of rat thymocyte apoptosis induced by diabetes and the possible mechanism of thymic involution in diabetes. Methods On the rat model of experimental diabetes induced with alloxan, the morphologic changes of thymocyte apoptosis were examined under electron microscope. Results A great number of apoptotic thymocytes were found in the thymic cortex in diabetic rats, with the thymocytes undergoing a series of apoptotic changes. The thymocytes became shrunken, forming numerous protrusions on the surface in a manner like zeiosis. The electronic density of cytoplasm was increased. The mitochondria became swollen and vacuolized, with the crista disordered in arrangement and reduced in number. The nuclear chromatin became condensed and marginated, and the nuclei became petaled, black ring-like and black hole-like, and cleaved to form apoptotic bodies, which were being engulfed by macrophages and epithelial cells. Besides, lots of plasma cells aggregated about the apoptotic cells and apoptotic bodies. Conclusion Massive apoptosis of thymocytes in rat could be induced by diabetes, which may be one of the major mechanisms of the marked reduction of thymocytes and the involution of thymus gland in diabetic rats.