Volume 49 Number 3

Association between chromatin configuration and developmental competence of germinal vesicle-stage oocytes in guinea pigs

Zhijie Zhang^a,?, Jiaming Zhang^a,?, Hongsheng Zhu^a,?, Huan Li^a,?, Yuchen Ma^a, Erhao Liang^a, Haochen Sun^a, Caiyue Xue^a, Xinyi Chu^a, Dishuo Chai^a, Yu Tian^a, Jiahang Lv^a, Hongshu Sui^a,*, Yimiao Zhang^a,*, Zhaoqing Gong^b,*

 
ABSTRACT:      Large quantities of oocytes for embryo engineering are obtained through in vitro maturation (IVM). Although IVM oocytes are arrested at the diplotene stage of the first meiosis, they exhibit distinct quality heterogeneity, and reliable selection criteria are urgently required to improve IVM efficiency. As guinea pigs share high similarities with human reproductive physiology, they serve as a suitable animal model to investigate oocyte chromatin configuration. In this study, germinal vesicle (GV) chromatin of guinea pig oocytes was classified into five subtypes (NSN, pNSN, SN-1, cSN-1, and SN-2) based on chromatin compaction. We further explored the relationship between chromatin configurations and developmental competence by monitoring changes associated with follicular and oocyte growth, tracking chromatin dynamics during hormone-induced in vivo maturation, and detecting RNA transcriptional activ ity.Chromatin gradually transitions from NSN to SN-2 as follicles and oocytes develop. The proportion of SN-2 oocytes increases progressively during in vivo maturation, accompanied by declining transcriptional activity. In conclusion, SN 2 represents the most mature GV chromatin stage in guinea pig oocytes, and RNA transcriptional activity is negatively correlated with GV-oocyte maturity.

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* Corresponding author, E-mail: hssui@sdfmu.edu.cn, 15137335275@163.com, gongzhaoqing2021@163.com

Received 8 Jul 2025, Accepted 16 Aug 2026