The presence of serum in embryo culture medium has been implicated for increased embryo's sensitivity to cryopreservation, compromised viability, abnormal embryo and fetal development. Hence, designing a serum free culture system is indispensable. The present study aims to compare the efficiency of the serum and granulosa cells monolayer free commercial culture system (SFCS) with the conventional serum supplemented co-culture system (SSCS) and optimized culture system (OCS). Generally, SFCS is designed explicitly for bovine oocyte maturation and embryo culture (SF-IVM and SF-IVC), and SSCS (based on M199, SS-IVM, and SS-IVC) is utilized for buffalo in vitro embryo production. However, OCS is a newly designed culture system in which oocyte maturation is performed in serum supplemented maturation medium, and the subsequent embryos are co-cultured with granulosa cells in serum free culture medium. To evaluate the effect of serum on buffalo embryo production, buffalo oocytes, and their subsequent embryos were cultured in SSCS, SFCS, and OCS, simultaneously. The percentage of cleaved embryos cultured in SSCS and OCS was approximately 4% higher as compared to SFCS. However, OCS significantly showed the maximum proportion of embryos that developed to the blastocyst stage (7d) and hatched (6d) as compared to the SFCS and SSCS. Additionally, OCS promoted the expression of developmentally important genes (BCL2-L1 and VEGF-A), cell number, and cryo-survival ability of blastocysts in comparison with SSCS. Taken together, OCS is more suitable for the oocyte maturation and culture of buffalo embryos. However, to design the serum free culture system, it is recommended to find suitable serum alternatives for in vitro oocyte maturation.

中文翻译：

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无血清培养系统培养水牛胚胎的发育潜力

胚胎培养基中血清的存在与胚胎对冷冻保存的敏感性增加、生存力受损、胚胎和胎儿发育异常有关。因此，设计一个无血清培养系统是必不可少的。本研究旨在比较血清和颗粒细胞单层无商业培养系统 (SFCS) 与传统补充血清共培养系统 (SSCS) 和优化培养系统 (OCS) 的效率。通常，SFCS 是专为牛卵母细胞成熟和胚胎培养（SF-IVM 和 SF-IVC）而设计的，SSCS（基于 M199、SS-IVM 和 SS-IVC）用于水牛体外胚胎生产。然而，OCS 是一种新设计的培养系统，其中卵母细胞的成熟是在补充血清的成熟培养基中进行的，随后的胚胎在无血清培养基中与颗粒细胞共培养。为了评估血清对水牛胚胎生产的影响，水牛卵母细胞及其后续胚胎同时在 SSCS、SFCS 和 OCS 中培养。与 SFCS 相比，在 SSCS 和 OCS 中培养的裂解胚胎的百分比大约高 4%。然而，与 SFCS 和 SSCS 相比，OCS 显着显示了发育到囊胚阶段 (7d) 和孵化 (6d) 的胚胎的最大比例。此外，与 SSCS 相比，OCS 促进了发育重要基因（BCL2-L1 和 VEGF-A）的表达、细胞数量和囊胚的冷冻存活能力。综合来看，OCS更适合水牛胚胎的卵母细胞成熟和培养。然而，为了设计无血清培养系统，