Mancozeb, a fungicide of ethylenebisdithiocarbamate group was orally administered at doses of 500, 600, 700 and 800 mg/kg body weight/day to normal virgin rats of Wistar strain for 30 days. The vaginal smear and body weight of the rats were recorded daily and rats were sacrificed on 31st day. Estrous cycle was effected by showing a significant decrease in the number of estrous cycle, duration of proestrus, estrus and metestrus with concomitant significant increase in the duration of diestrus in all the mancozeb treated groups when compared with controls. There were a significant decrease in the number of healthy follicles and a significant increase in the number of atretic follicles in all the mancozeb treated groups when compared with controls. The histologic observation of the ovary revealed the presence of less number of corpora lutea and the size of the ovary was also reduced in high doses of mancozeb treated rats. There was a significant increase in the thyroid weight in all the mancozeb treated rats except in 500 mg/kg/d. In rats treated with 500 mg/kg/d showed a significant increase in the level of total lipids in the liver. In rats treated with 600 mg/kg/d mancozeb showed a significant decrease in the levels of glycogen and total lipids in the uterus and total lipids in the liver. In rats treated with 700 mg/kg/d showed a significant decrease in the levels of protein in ovary, glycogen, total lipids, phospholipids and neutral lipids in the uterus and a significant increase in the levels of phospholipids, neutral lipids in the ovary and total lipids, phospholipids and neutral lipids in the liver. In rats treated with 800 mg/kg/d showed a significant decrease in the levels of protein and glycogen in the ovary and protein, glycogen, total lipids, phospholipids and neutral lipids in the uterus and a significant increase in the levels of total lipids, phospholipids and neutral lipids in the ovary and liver when compared with controls. These observed effect of mancozeb on the estrous cycle, follicles and biochemical constituents may be due to imbalance in the hormone or toxic effect.

Carbofuran, a systemic N-methyl carbamate pesticide was orally administered with the doses of 0.4, 0.7, 1 and 1.3 mg/kg body weight/day to normal virgin female Swiss albino mice for 30 days. The vaginal smear and body weight of mice were recorded daily and mice were sacrificed on the 31st day. Estrous cycle was effected by showing a significant decrease in the number of estrous cycle and the duration of each phases of estrous cycle with concomitant significant increase in the diestrus phase in 1 and 1.3 mg/kg/d carbofuran treatment when compared with that of control mice. There was a significant decrease in the number of healthy follicles and a significant increase in the number of atretic follicles in 1 and 1.3 mg/kg/d treated groups when compared with the control. The histologic observations of the ovary revealed the presence of less number of healthy follicles and more number of atretic follicles in high dose of carbofuran treated mice. There was a dose dependent decrease in the body weight. The ovary weight was also decreased significantly in 1.3 mg/kg/d carbofuran treatment. There were no significant change in the weight of the organs such as uterus, kidney, adrenal, liver, spleen, thymus and thyroid. These observed effects of carbofuran on the estrous cycle and follicles may be due to a direct effect on the ovary or the hypothalamo-hypophysial ovarian axis causing hormonal imbalance.

Stem cell based toxicity prediction plays a very important role in the development of the drug. Unexpected adverse effects of the drugs during clinical trials are a major reason for the termination or withdrawal of drugs. Methods for predicting toxicity employ in vitro as well as in vivo models; however, the major drawback seen in the data derived from these animal models is the lack of extrapolation, owing to interspecies variations. Due to these limitations, researchers have been striving to develop more robust drug screening platforms based on stem cells. The application of stem cells based toxicity testing has opened up robust methods to study the impact of new chemical entities on not only specific cell types, but also organs. Pluripotent stem cells, as well as cells derived from them, can be evaluated for modulation of cell function in response to drugs. Moreover, the combination of state-of-the -art techniques such as tissue engineering and microfluidics to fabricate organ- on-a-chip, has led to assays which are amenable to high throughput screening to understand the adverse and toxic effects of chemicals and drugs. This review summarizes the important aspects of the establishment of the embryonic stem cell test (EST), use of stem cells, pluripotent, induced pluripotent stem cells and organoids for toxicity prediction and drug development.