Estrous Cycle and Early Pregnancy of White Mice Exposed to Methomyl

Document Type: Original Research Paper


1 Animal Biology Division, Institute of Biological Sciences, University of the Philippines Los Baños, College, Los Baños 4031, Laguna, Philippines Biology Department, Central Mindanao University, Musuan Maramag Bukidnon, Philippines

2 Animal Biology Division, Institute of Biological Sciences, University of the Philippines Los Baños, College, Los Baños 4031, Laguna, Philippines Department of Biological Sciences and Environmental Studies, University of the Philippines Mindanao, Mintal, Davao City 8000, Philippines

3 Animal Biology Division, Institute of Biological Sciences, University of the Philippines Los Baños, College, Los Baños 4031, Laguna, Philippines

4 Animal Biology Division, Institute of Biological Sciences, University of the Philippines Los Baños, College, Los Baños 4031, Laguna, Philippines Research and Development Center/College of Arts and Sciences, Laguna State Polytechnic University, Siniloan Campus, L. de Leon St., Brgy. Acevida, Siniloan, Laguna, 4019, Philippines


Methomyl is an oxime carbamate pesticide that is widely used in the Philippines. This insecticide is known to be an endocrine disrupting chemical and a potent genotoxic in mammalian cells. However, limited studies were conducted specifically on its direct effects on estrous cycle and its teratogenic effect. This study aimed to (a) assess the effect of methomyl on the body weight and on the estrous cycle of mice, and; (b) examine the teratogenic effect of methomyl on the progeny of the female albino mice. Five week-old experimental mice in three treatment setups were used in the study for both independent experiments. The treatment schedule for pregnant mice was administered during organogenesis (day 6 to 15 of gestation). Results showed that the average gained weight of the mice of both high dose (HD) and low dose (LD) groups were lower as compared to the average gained weight of the control group but did not show any statistical significant differences (p=0.562). For the experiment 1, methomyl significantly (p=0.013) affect the estrous cycle of the mouse especially in LD group. For experiment 2, results revealed that there was a significant difference among the treatment set-ups (p=0.0001) in terms of fetal morphometric measurement. Furthermore, abnormality and high number of resorption was also observed in both LD and HD treatment groups. Therefore, methomyl significantly affect the body weight, estrous cycle and fetal morphometry. This further confirm that methomyl is an endocrine disrupting and genotoxic chemical that affects the estrous cycle and causes teratogenic effect.


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