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Objectives: To investigate the effects of preimplatation exposure of (F1×F1) strain mouse embryos to different dosages (0.3 VS 0.6mM) of ammonium chloride.
Study Method: Total of 267, one-cell stage mouse embryos were randomly allocated to culture in either M16 medium (control), or the other two experimental groups which are M16+0.3 mM ammonium chloride or M16-0.6 mM ammonium chloride. Embryos were left in culture for 3 days before being transferred to 2.5 day pseudopregnant recipients. Embryo morphology was assessed after 1, 2 and 3 day of culture. The number of implantation site, fetuses, moles and any gross abnormality found were noted.
Results: There was no significant difference in the number of embryos achieved morula or more advanced stage after three days of culture between the two treatment groups. Implantation rate was significantly higher in the group of embryos exposed to 0.3 mM ammonium chloride compared to those exposed to 0.6 mM ammonium chloride (Fisher Exact test, P<0.05). Moreover, preimplantation pregnancy loss was significantly higher in the group of embryos exposed to 0.6 mM ammonium chloride compared to the treatment group (Fisher exact test, P<0.05). There was one grossly abnormal fetus detected in the group of embryos exposed to 0.3mM ammonium chloride. The abnormality observed was polydactyly of both hind limbs with the incidence of 20% per fetus obtained.
Conclusions: The study showed that preimplantation exposure of mouse embryos to higher dosage of ammonium chloride (0.6mM) resulted in a significant decrease in implantation rate and significant increase in preimplantation pregnancy loss when compared to a lower dosage of ammonium chloride (0.3mM). This implies that preomplantation exposure to ammonium chloride impairs implantation potentials of mouse embryos, possibly in a dose-depending fashion.