Abstract
Irradiation is known to affect the female reproductive organs; however, no detailed reports have been made concerning the effects of irradiation timing and dose on the reproductive organ’s development. Therefore, this study investigated the effects on ovarian development in adult rats irradiated with γ-rays at fetal, neonatal, weaning, and early sexual maturation.
Female F344 rats mated with male Eker rats and those F1 rats were irradiated with a single dose of 0.5 or 2 Gy of γ-rays on fetal day 15 or 19 (FD15 or 19), or postnatal day 5, 20, or 49 (PND5, 20, or 49). F1 females were reared to 27 weeks of age and necropsied, and HE-stained specimens of the reproductive organs were prepared for histopathological examination (n=10 to 22 per group). In all ovaries, the corpus luteum and follicle numbers were also counted. In addition, PCNA-stained specimens were used to count primordial follicles.
At 2 Gy, the corpora lutea and follicles depletion was observed in the FD15, PND5, and PND20 groups. Instead of the lost follicles consisted of granulosa cells, numerous tubular structures composed of Sertoli-like cells derived in the testis were noted. In the FD19 group, the ovaries showed resistance to γ-ray. In the PND49 group, the number of corpora lutea was normal; however, follicles including the primordial ones reduced. At 0.5 Gy, the ovaries appeared histopathologically normal in all groups; however, the follicles decreased in the FD15 and PND5 groups. In conclusion, it was found that the same dose at different times of irradiation caused significant differences in subsequent ovarian development, and the degree of change depended on the γ-ray dose. In addition, quantitative analysis revealed a decrease in primordial follicles, which might have been indeterminable by routine histopathological examination.
