This study was to determine the effect of boron supplementation on the morphology of kidney tissue in ostrich chicks. A total of 48 newly hatched ostrich chicks were used and randomly assigned to six groups and exposed to various doses of boric (0, 40, 80, 160, 320, 640 mg/L) in drinking water for 90 days, respectively. The kidneys were removed and tissue sections were stained with HE for morphological examination and semiquantitative evaluation. Microscopic observation showed that compared with the control group (0 mg/L), the structure of renal corpuscle and renal tubular was clearer in ostrich chicks fed with 40 and 80 mg/L boron. Furthermore, the brush borders were more abundant. On the other hand, in groups fed with 320 and 640 mg/L boron, histopathological degeneration occurred with the characters of cellular swelling and dissociation, loose cytoplasm, nuclear pycnosis, and basement membrane detachment in some tubular cells. Debris deposit was accumulated in the tubular lumen, especially in the proximal tubule. And the percentage of injured tubules was more than 50% in these groups. Moreover, the extent of kidney injury in group receiving 640 mg/L boron was more obvious with increasing tubular dilatation, tubular cell granular degeneration, interstitial inflammation and associated capsular retraction. Taken together, these findings showed that 40 and 80 mg/L boron supplementation may promote the kidney development; while 320 and 640 mg/L boron supplementation have obviously adverse effect, and the toxic effect was dose-dependent.

Key words: Boron, Kidney tissue, Morphology, Ostrich chicks