Objective:TO explore the effectiveness of splenic tissue autotransplantation in restoring host defense. Methods: Rabbits were divided into three groups,Sham Operation(SO), Splenic Autotransplantation(SA)and Total Splenectomy(TS), and dynamic changes in histology and immunology were observed for over 24 weeks. Results: Histologic study shows that the white pulps were poorly developed and central arterioles disappeared in the regenerated splenic tissue. The weight of regenerated spleens recovered six months later in SA was 11% of that in SO, and was significantly reduced comparing with the implanted weight( P ＜0.05). Tere were no significant difference in the number of T lymphocytes and the levels of serum lysozyme among the three groups. A poor antibody response by the rabbits of SA and TS as compared to those of SO was noted after the primary intravenous administration with sheep red blood cells. After the challenge with type 3 pneumococci intravenously, pneumococcal clearance from bloodstream in SA did not differ significantly from that in TS,but was marKedly delayed compared with that in SO(P＜0.01). Conclusion: The results indicate that the low quantity and poor quality of the regenerated spleens may contribute to the inferior immunoprotective ability of 1/3 splenic autotransplantation. Therefore, it implies that the regenerated spleens can not fully compensate the original one in im-munology, especially, host resistance to infection.

BACKGROUND: The deficiency of perfect animal femoral head necrosis model limited its further investigation. OBJECTIVE: To verify the feasibility of establishing rabbit femoral head necrosis models using liquid nitrogen rsfdgeration method, and to provide a foundation for subsequent research. METHODS: A total of 20 adult, New Zealand, white rabbits were selected in the study. The round ligament of femur was not cut off and femoral head was not dislocated, and the exposed femoral head were quick frozen using cotton bud carrying liquid nitrogen for successive 25 times, with 10 s per time. The specimens were examined by gross anatomy, X-ray film, MRI and histological observation at day 3, 7 and weeks 2, 4, 6, and 8 after operation. RESULTS AND CONCLUSION: The histolOgical section showed that chondrocyte, osteccyts, and myelold tissues presented necrosis in freezing and periphery at 3days after model preparation, and the repair process appeared at 2weeks after operation. The articular surface of femoral heads appeared collapse at 4 weeks after operation, and these changes became obvious at 6 weeks. The femoral head presented ostecarthdtis-like disorder, with seriously collapsed articular surface at8 weeks, and the contour of femoral head changed in 2 animals. The results demonstrated that without hip dislocation, rabbit femoral head necrosis models can be established successfully using liquid nitrogen refrigeration method. This method is simple, feesible, with high succeed rate, which can be used in subsequent research.