Manganese () is a trace element that is essential for normal physiology, and is predominantly obtained from food. Several lines of evidence, however, demonstrated that overexposure to exerts serious neurotoxicity, immunotoxicity and developmental toxicity, particularly in male. The present study aimed to evaluate the effect of 0, 1.0, 3.3, and 10 mg/kg/day doses of on the reproductive organs in the immature female rats. Rats (PND 22; S.D. strain) were exposed to () dissolved in drinking water for 2 weeks. The animals were sacrificed on PND 35, then the tissues were immediately removed and weighed. Histological studies were performed using the uteri tissue samples. Serum LH and FSH levels were measured with the specific ELISA kits. Body weights of the experimental group animals were not significantly different from those of control group animals. However, ovarian tissue weights in 1 mg and 3.3 mg dose groups were significantly lower than those of control animals (p<0.05 and p<0.01, respectively). Uterine tissue weights of 3.3 mg dose groups were significantly lower than those of control animals (p<0.01), while the 1 mg dose and 10 mg dose failed to induce any change in uterine weight. Similarly, only 3.3 mg dose could induce the significant decrease in the oviduct weight compared to the control group (p<0.05). Non-reproductive tissues such as adrenal and kidney failed to respond to all doses of exposure. The uterine histology revealed that the exposure could affect the myometrial cell proliferation particularly in 3.3 mg dose and 10mg dose group. Serum FSH levels were significantly decreased in 1mg dose and 10 mg groups (p<0.05 and p<0.01, respectively). In contrast, treatment with 1 mg dose induced a significant increment of serum LH level (p<0.05). The present study demonstrated that exposure is capable of inducing abnormal development of reproductive tissues, at least to some extent, and altered gonadotropin secretions in immature female rats. Combined with the well-defined actions of this metal on GnRH and prolactin secretion, one can suggest the might be a potential environmental mediator which is involved in the female pubertal process.

We examined the morphometric characteristics and fluctuating asymmetry of diploid and triploid marine medaka, Oryzias dancena. We used morphometric parameters the truss and classical dimensions. Significant differences in all the classical and truss dimensions of the diploid and triploid fish. All the dimensions of the triploid fish were greater than those of the diploid fish. The triploid marine medaka shows sexual dimorphism in these characters, and the sexual dimorphism of the triploid marine medaka is similar to that of the diploid marine medaka. Thus, the growth of triploid marine medaka is faster than that of the diploid fish, and it displays clear sexual dimorphism, with male fish having longer dorsal and anal fins than female fish. we examined fluctuating asymmetry of eye diameter, maxilla length, operculum length, number of pectoral fin ray and number of pelvic fin ray. In all experimental groups, Eye diameter and maxilla length showed no significant difference between left side and right side (P>0.05). Trends of operculum length in triploid male group and pectoral fin ray's number in diploid male group showed similar trend with trends of operculum length in triploid female group and pectoral fin ray’s number in diploid female group. However, trends of operculum length in diploid male group and pectoral fin ray's number in triploid male group showed opposite trend with trends of operculum length in diploid female group and pectoral fin ray’s number in triploid female group. Trend of pelvic fin ray's number in all groups showed similar trend with trend of pectoral fin ray’s number in all groups.