卵泡发育是哺乳动物生殖过程中至关重要的环节。线粒体融合蛋白2 (mitofusin 2，Mfn2)是一种参与调节线粒体融合的GTP酶，是维持线粒体网络完整性和功能的关键因素，其在卵泡发育过程中调控线粒体功能与内质网应激的具体作用尚不明确。基于此，本研究探讨了Mfn2在成年绵羊卵泡发育过程中的作用。通过收集大、中、小卵泡并分离大卵泡的颗粒细胞(granulosa cells，GCs)，利用qRT-PCR和Western blot检测Mfn2在不同卵泡中的表达水平，并通过免疫荧光技术确定Mfn2在卵泡中的定位。同时，检测了线粒体自噬相关蛋白Pink1、内质网应激蛋白(Grp78、Perk、Chop)和凋亡相关蛋白(Bcl2和BAX)的表达。进一步通过在GCs中转染siRNAs敲降Mfn2，评估细胞内Ca²⁺积累及线粒体膜电位的变化，并检测上述蛋白的表达水平。结果表明，Mfn2在大卵泡中的表达显著高于小卵泡，且主要表达于GCs。与小卵泡相比，大卵泡中Pink1、Grp78、Perk、Chop和BAX的表达显著降低，而Bcl2的表达显著增加(P<0.01)。Mfn2敲降后，细胞内Ca²⁺水平及线粒体膜电位显著降低，Pink1、Grp78、Perk、Chop和BAX的表达显著升高，而Bcl2的表达显著降低(P<0.01)。Mfn2可能通过调控线粒体功能及内质网应激，影响绵羊卵泡发育过程中的细胞凋亡。

Follicle development is a crucial step in mammalian reproductive processes, the specific role of Mfn2 in regulating mitochondrial function and endoplasmic reticulum stress in this process is still unclear, this study aimed to investigate the role of Mfn2 in the follicular development of adult sheep. Large, medium, and small follicles were collected, and granulosa cells (GCs) were isolated from large follicles. The expression levels of Mfn2 in different follicles were detected using qRT-PCR and Western blot, and the localization of Mfn2 in follicles was determined through immunofluorescence. Additionally, the expression levels of the mitochondrial autophagy-related protein Pink1, endoplasmic reticulum stress proteins (Grp78, Perk, Chop), and apoptosis-related proteins (Bcl2 and BAX) were detected. Furthermore, siRNAs were transfected into GCs to knock down Mfn2 expression, and changes in intracellular Ca²⁺ accumulation and mitochondrial membrane potential were evaluated, along with the expression levels of the aforementioned proteins. The results showed that Mfn2 expression was significantly higher in large follicles compared to small follicles and was primarily localized in GCs. Compared to small follicles, the expression levels of Pink1, Grp78, Perk, Chop, and BAX were significantly lower in large follicles, while Bcl2 expression was significantly increased (P<0.01). After Mfn2 knockdown, intracellular Ca²⁺ levels and mitochondrial membrane potential were significantly reduced, while the expression levels of Pink1, Grp78, Perk, Chop, and BAX were significantly increased, and Bcl2 expression was significantly decreased (P<0.01). Mfn2 may influence cell apoptosis during sheep follicular development by regulating mitochondrial function and endoplasmic reticulum stress.