RESUMO
The present study aimed to evaluate the histological changes of the testis in an irradiated rat under the effect of oestrogen as a radioprotective agent. Eighty adult male albino rats were used in this work and divided into 8 equal groups. Group I was considered as a control, group II was exposed to gamma radiation at a dose rate 6 Gy, group III was intramuscularly injected with a single dose of oestrogen [0.166 mg / 100 g b.w.], group IV was injected with fractionated doses of oestrogen [0.09 mg/ 100 g b.w.] daily for 7 days, group V and VI were injected with the same single and fractionated doses 10 and 5 days pre-irradiation respectively, group VII and VIII were injected with the same single and fractionated doses 7 and 5 days post-irradiation respectively. Twenty-one days post-irradiation and treatment, the animals were sacrificed, the testis was isolated and paraffin sections were prepared and stained by haematoxylin and eosin to study the general microscopic structure as well as measurement of thickness of germinal epithelium and diameter of seminiferous tubules. The obtained data were statistically analyzed by Student's ttest. The irradiated testis showed vacuolization and necrosis of spermatogenic cells, damage of Sertoli cells, rare sperms and reduction of, the germinal epithelium thickness and the diameter of seminiferous tubules in comparison with control group. With injection of both doses of oestrogen or pre-irradiation injection, the testis was nearly similar to normal pattern. On the other hand, with post-irradiation injection, the testis was nearly similar to irradiation pattern. It was concluded that pre-irradiation injection of single or fractionated doses of oestrogen could result in improving the effect on the structural changes of testis in the irradiated rat