Background: Parthenogenetic activation is a possible way to produce homogeneous embryos with the some ploidy.Probably such embryos could be used in other areas of biotechnology. Calcium signals are known as important regulators of oocyte activation. Extracellular calcium is required for initiation of meiotic resumption and development. Calcium ionophore A23187 is known to elevate intracellular Ca 2+ levels in the cytoplasm of oocytes through the influx of calcium from extracellular spaces.This study investigated the role of extracellular calcium on calcium ionophore inducing oocyte parthenogenetic activation in mouse.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 II oocytes enclosed in cumulus masses were collected from oviduct 14 hours after HCG injection. The group in which oocytes were cultured in media alone was the control, those cultured was in the presence of 5mM calcium ionophore A23187 for 5 minutes designated as experiment group. Consequently, the three treatments I, II and III are referred to culture in T6 medium containing 0, 1.7, 3.4 mM calcium. Oocytes were cultured for 72 hours and embryo development was assessed.Results: After 72 hours, in treatments I, II, III from experiment and control groups the percentage of cleavage rate was 0%, 10.1%, 27.2% and 11.3%, 44.2%, 61.3%; respectively.Cleavage rate in experiment group was higher than control group (p<0.05).Conclusion: After 72 hours, in treatments I, II, III from experiment and control groups the percentage of cleavage rate was 0%, 10.1%, 27.2% and 11.3%, 44.2%, 61.3%; respectively. Cleavage rate in experiment group was higher than control group (p<0.05).

Extracellular Ca2+ concentration ([Ca2+]o) may be one of the factors affecting atrial natriuretic factor (ANF) release. In the previous studies, there are opposite reports about the effect of [Ca2+]o on ANF secretion. Therefore, the effect of [Ca2+]o depletion on ANF secretion and gene expression was studied in the present research. Isolated right atria from rats were perfused for 6 and 2 hours in the presence and absence of [Ca2+]o, and ANF secretion were measured using radioimmunoassay method. Cyclohexamide was used in another group as a protein synthesis inhibitor. ANF mRNA level in atria measured by Real time PCR. [Ca2+]o depletion induced a significant increase in basal ANF release. This stimulatory effect peaked at 2 h, then started to decrease and reached around basal levels by 6 h. Protein synthesis inhibition by cyclohexamide did not abolish or significantly decrease the stimulatory effect of Ca2+-free media on ANF secretion. The ANF gene expression was not significantly affected by Ca2+-free media. These results suggest that the contractile and endocrine function of atrial cardiocytes are differently affected by [Ca2+]o and may represent an adaptation to the dual roles of the atrial myocytes contraction and secretion.