Effect of Thiol Compound Cysteamine and β-Mercaptoethanol on In Vitro Maturation and Embryo Development Oocytes with/without Cumulus NMRI Mouse

Background and Aim: The present study examined the relationshipbetween cysteamine and β-mercaptoethanol on in vitro maturation andembryonic development in oocytes with-cumulus and without cumulusNMRI mouse. Unfavorable conditions in cell culture medium and highlevels of free radicals and eggs low quality seem to be the cause of failureof this method and may cause low fertility rate. The purpose of this studywas to compare maturation and embryo development germinal vesiclewith and without cumulus in NMRI mice in the presence and absence ofcysteamine and β-mercaptoethanol.Methods: In this study, 4-6-week immature NMARI mice were used.Animals were handled according to the guidelines for the care and use oflaboratory animals and maintained in a 12 D photoperiod under constanttemperature and relative humidity. Food and water were providedsuitable, and 7.5 unites PMSG (pregnant mare serum gonadotropin) wasused for ovaries stimulation. After 48h, mice were killed with dislocationof cervical vertebrae. GV oocytes with and without cumulus cells wereisolated from ovaries and cultured in TCM199 media in addition 100μm BME and CYS for 24 hours. Then mature oocyte (MII) were fertilizedwith sperm in BSA+T6 medium (IVF). Then, they were analyzed usingSPSS software and evaluated for development egg to blastocyst under aninverted microscope. Blastocyst formation in a defined IVM medium formouse immature oocytes increased. The effect of supplementation withCys or β-ME on IVM rate and fertilization and developmental competencefollowing intracytoplasmic sperm injection (ICSI) were investigated. TheICSI procedure was performed according to the method of Yong et al.Results: In the present study, our findings indicated that 100 μm BME &CYS in medium culture can improve in-vitro maturation (P<0.05). Also,oocytes with cumulus increased in vitro maturation in medium culture(P<0.05). The addition of cysteamine and β- mercaptoethanol to definedmaturation medium enhanced the blastocyst formation. There is a positiveand meaningful relation between BME & CYS and in-vitro maturationoocytes in stages 2-cell, 4-cell, 8-cell, and blastocyst. Existence cumulusoocytescomplexes (COCs) increased the maturation in-vitro. Conclusion: The oocytes with-cumulus may play an important rolein the oocyte maturation by regulating the meiotic progression andsupporting the cytoplasmic maturation. High efficiency in the mouse byfurther increasing the GSH reservation created by oocytes complexeswas matured in vitro in TCM199 media. In all supplemented groups,the intracytoplasmic GSH concentration was significantly higher thanthe control medium for the improvement in embryo production. Thereare a positive and meaningful relation between BME&CYS and in-vitromaturation oocytes in the stages 2-cell, 4-cell, 8-cell, and blastocyst. Theexistence of cumulus-oocytes complexes (COCs) could increase the invitromaturation.

کلیدواژه ها:

Cysteamine ، β-mercaptoethanol ، Cumulus oocytes ، Embryonic development