Abstract： Objective To investigate the histopathologic features, changes of blood-ocular barrier and the expression of tumor necrosis factor-α (TNF-β) and interleukin-1β(IL-1β in vitreous body of Wistar rats with zymosan-induced endophthalmitis.Methods Random number table method was used to assign the Wistar rats into saline control group (SC group,n=168) and endophthalmitis group (EO group,n=168).Rats of EO group received intravitreal injection of zymosan to induce endophthalmitis, while the control rats received injection of equivalent-ose sterile saline.The rat eyes were observed for signs of ocular inflammation and enucleated for histopathological examination at 6 h, 12 h, 1d, 2d, 3d, 5d and 7 d after injection respectively.Furthermore, aqueous humor for determination of protein levels and vitreous body for levels of TNF-α and IL-1βwere collected.Results Severe inflammatory response in the eyes was observed in EO group within 6 h to 3 d after zymosan injection, and was basically resolved after day 7.A peak intraocular leucocyte count was observed in EO group on day 1 [(482.63 ±91.15) cells/eye] that rapidly declined on day 3[(131.25±7.95) cells/eye].The increased levels of TNF-α and IL-1βin EO group peaked at 24 h after injection [TNF-α: (331.17±9.81) ng/L, IL-1β (2 156.09± 440.27) ng/L, respectively], persisted to 48 h after injection, and began to decline rapidly afterwards.On day 7 after injection, levels of TNF-α and IL-1βreturned to baseline[TNF-α: (5.55±2.27)ng/L, IL-1∞ (43.66±8.73) ng/L, respectively].Compared with SC group 6 h after injection, significantly higher protein levels in aqueous humor were detected in the EO group at all the time points (all P＜0.01).Conclusions Acute experimental endophthalmitis was successfully induced in the Wistar rats with intravitreal injection of zymosan.Massive leucocyte intraocular infiltration, blood-ocular barrier breakdown and high levels of TNF-α and IL-1βexpression in vitreous body may be the major pathologic characteristics in this experimental endophthalmitis model.