Electron microscopic examination of the effects of methyl parathion exposure on the ovaries.

Objective: In our study, we aimed to investigate histopathological effects of chronic methyl parathion exposure on ovaries at electron microscopic level.

Materials And Methods: In this study, Wistar albino type, adult, female rats with an average weight of 190-250 g were used. 30 female rats, included in this study, were divided into 3 groups. Group I received only saline and was evaluated as the control group, whereas Group II received 1/50 percent of LD50 dose of methyl parathion and Group III received 1/20 percent of LD50 dose of methyl parathion every day at 130 pm orally by gavages during two estrus cycles (8 days). The rats at proestrus stage on the morning of 9th day of the study underwent bilateral ovariectomy. Ovarian tissues of the control and drug groups were examined under the electron microscope; primordial and growing follicles were included in the evaluation, however, corpora lutea were excluded taking into account the presence of remaining regressive corpora lutea from the previous cycles.

Results: Following examination of ovarian tissues of rats exposed to 1/50 and 1/20 percent of LD50 dose of Methyl parathion at electron microscopic level, it was detected that significant structural changes had occurred in developing follicles and ovarian stroma in both drug groups, and that primordial follicles had not been affected significantly from methyl parathion but necrosis had been developed in oocyte and granulosa cells of developing follicles, and that in 1/20 group in addition to these changes, apoptotic changes had been found in granulosa cells of developing follicles.

Conclusions: As a result of chronic exposure to methyl parathion, rat ovaries are significantly affected and follicular development is impaired. This state may explain the cause of infertility due to chronic pesticide exposure.