Special features of nanoparticles have resulted in their widespread use. Small molybdenum trioxide (MoO ) nanoparticles can translocate from the entry portals into the circulatory and lymphatic systems and ultimately to body tissues and organs depending on their composition and size. In this research, sixty Wistar rats weighting 180-250 g were divided into 6 groups (n=10) randomly: Group 1 (Control) did not receive any medicine. Group 2 (Sham) received intraperitoneal normal saline for 35 days on a daily basis. Groups 3, 4, 5 and 6 received 50, 100, 200, and 300 mg/kg MoO , respectively, the same way in the sham group and at the same interval. At the end of the experiment, the rats 3 were weighted again and anesthetised. Then blood samples were taken from their hearts to determine the serum levels of estrogen, progesterone, and gonadotropins. Their ovaries were removed and ovarian volume, follicular diameter, number of each follicle type, and oocyte volume were determined. Results indicated that MoO nanoparticles strongly reduced body and ovarian weights in the rats. Moreover, a significant decrease was observed in ovarian volume, the number of follicle types, oocyte volume and follicular diameter. The nanoparticles increased the number of atretic follicles via ovarian tissue structure. MoO nanoparticles decreased serum estrogen level and increased serum level of FSH that was associated with disruption in the regulation of progesterone and LH secretion. The findings showed that MoO nanoparticles could bear negative effects on ovarian structure and function.
KEY WORDS: Molybdenum trioxide Nanoparticles; Ovary; Stereology; Reproductive hormones; Rats.