| Objective: Multiple sclerosis(MS) is an autoimmune disease, the cure rate is very low, with high morbidity and mortality. Currently considered genetic, infection, living environment, and many other causes lead CD4+ T cell-mediated immunity to disease, but its specific research on the pathogenesis is still unclear.Thymus is an important immune organ because T cells remove no self-tolerance cells by apoptosis in order to maintain the stability of the body. The relationship of autoimmune diseases and their immune- tolerance disorder is close.Apoptosis of thymocytes is researched little currently, our study investigated the course of variation of thymocyte apoptosis in EAE rats , and provide theoretical basis for research of thymic function.Methods: 70 female Wistar rats, 6 - 8 weeks old, weighing 180g -220g, were randomly divided into two groups,(1) normal group (2) EAE group, rats immuned before and after vaccination were weighed at different times, and the situations were observed such as mental states, eating and drinking, urine and stool,and the strength of tail and limbs after the day of immunization.In 3th days and 5th days after onset of illness and recovery period, we took 10-12 rats in each group randomly, took out the thymus, measured the rats body weight and thymus weight,accounted thymus index, and observed the thymocytes changes in light microscopyand electron microscopy,we also observed and compared thymocyte apoptosis by using flow cytometryResults: electron microscopy, light microscopy of rat thymus observation ,flow cytometry showed that the typical changes of thymocyte apoptosis in EAE model.Light microscopy of rat thymus: Group structure of the normal group and the restoration of normal cortex, medulla dense lymphocyte boundaries clear that nuclear was blue purple; among the third day group, the fifth day group, and the recovery group, apoptotic cells of the third day group more, showing a significant thymus atrophy, cortical thinning significantly, reducing the number of lymphocytes, cells loose, increased number of apoptotic cells, nuclear chromatin condensation, nuclear pyknosis; while on the fifth day group compared with the three days group apoptotic cells decreased significantly.Electron microscopy of rat thymus: In the normal group and recovery group cortex seen in the number of lymphocytes, cells closely arranged, no expansion of mitochondria, rough endoplasmic reticulum well-developed high-density nucleus, chromatin evenly distributed euchromatin are more clearly show the electronic low-density areas, showing the distribution of chromatin along the nuclear membrane, nucleolus clear cell membrane integrity.Compared with the normal group lymphocyte reduce in the third day group and the fifth day group;in the third day group macrophage phagocytosis of apoptotic bodies can be seen.Rat thymus weight: normal group327.17±40.71, third group of 135.83±40.88, fifth day of group 229.83±62.66, Recovery Group307.17±49.60; in the third day group and the fifth group there are differencesthe of thymus weight compared the normal group ;between the third day group and the fifth group day there are differences (P <0.05);normal group and recovery group was no statistically significant (P> 0.05).Rat thymus index: Normal group, 1.47±0.28, third group of 0.74±0.13, the fifth day group 1.4757±0.33, recovery group 1.3558±0.23902; the thymus index of the third day groupthe is significantly higher (P <0.05), the thymus index of other groups there is no statistical significance (P> 0.05).Flow cytometry: Flow cytometry showed that apoptosis rate of each group: normal group3.98%±1.05%, the third day group of 10.36%±3.75%, the fifth day group 3.69%±0.67%, the recovery group3.26%±1.00;on the third day rats thymocyte apoptosis rate is significantly higher (P <0.05);in the other groups thymocyte apoptosis rats with there is no statistical significance when compared (P> 0.05).Conclusion: In the EAE model, incidence of apoptosis is in rat model ;the incidence of apoptosis in rat thymus cells highest in the third day, the fifth day less than the third day, no significant difference between recovery and the normal group. thymus has to refolding. electron microscopy is cell apoptosis effective detection method.
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