BACKGROUND: Indisputable population exposure to widespread electromagnetic fields, has grown concerns over the probable health effects of these fields. OBJECTIVE: The present study was aimed to examine the possible effects of 50 Hz extremely low frequency electromagnetic field (ELF-EMF) exposure on the number and quality of mice blastocysts. MATERIALS AND METHODS: In present study, 66 NMRI pregnant females divided into two treated and non-treated groups. The treated group exposed to ELF-EMF (50 Hz and 6×10(-3) T). Subsequently, embryos were collected by flushing the uterine horn and Fallopian tubes on the day 3 of gestation. Number of trophoectoderm (TE) and Inner Cell Mass (ICM) cells in blastocysts were determined after differential nuclei staining using a modified method. Furthermore, number of all flushed blastocysts calculated in each group. RESULTS: There was no significant difference in mean number of blastocysts in treated (6.64±1.34) and none treated (8.22±1.59) groups. In treated group, there were significant decreased in total cell number of blastocysts (p=0.000), number of ICM cells (p=0.000), and number of TE cells (p=0.001) whereas the ratio of ICM/TE cells increased (p=0.002). CONCLUSION: The data indicate that ELF-EMF is able to affect cellular composition of blastocysts, but it can't omit total volume of blastocysts.
