P-76: Cytogenetic Investigation of Parthenogenetic Mouse Embryos Generated from In Vitro Activated Oocytes by Hydrostatic Pressure in The Presence of Calcium Ionophore and Ethanol

Background: The advances in cytogenetic techniques during the last few years have permitted not only the study of large populations of wild and domestic animals, but also the detection of chromosome anomalies in embryos. Chromosomal abnormalities are the most common cause of embryonic and fetal mortality in mammals. Most reports of chromosome anomalies in parthenogenetic embryos describe numerical aberrations comprising aneuploidies, haploidy, polyploidy and mixoploidy. Hydrostatic pressure specifically affects centriole microtubules and that proximal microtubuletriplets are more resistant than distal microtubule doublets. The present study has been carried out to investigate the effects of hydrostatic pressure in the absence or presence of calcium ionophore and ethanol on improve of chromosomal complements in 2-cell parthenogenetic embryos. Materials and Methods: 6 to 8-week-old female NMRI mouse were superovulated by an injection of 10 IU of PMSG, followed by 10 IU HCG 48 hours later. Metaphase ΙΙ oocytes were collected from oviduct 14 hours after HCG injection. Oocytes transferred to T6 medium and randomly assigned to following groups: non- treatment (control), hydrostatic pressure exposure (treatment I), 5μM calcium ionophore exposure (treatment II), ethanol exposure (treatment III), 5μM calcium ionophore with hydrostatic pressure exposure (treatment IV) and ethanol 7% with hydrostatic pressure exposure (treatment V). Groups of activated oocytes were further treated with 5 mg/ml cytochalasin B for 4 hours. About 24-hour post oocytes activation, slides were prepared according to an ‘air drying’ technique and the chromosomal complement of 2-cell embryos was studied by giemsa staining. Results: Results indicated that in embryos treated by calcium ionophore and hydrostatic pressure observated the most incidence of normal chromosome (Diploidy and Tetraploidy) (84%) and fewest incidence of anormal chromosome (haploidy, triploidy and mixopliody) (16%) observed compared with control group and other treatments (p<0.05). Conclusion: It suggests that the exposure to hydrostatic pressure in the presence of calcium ionophore and ethanol can be improve chromosomal complements in 2-cell parthenogenetic embryos.