Endoplasmic reticulum remodeling in oocyte cytoplasmic maturation: calcium signaling, organelle communication, and clinical implications for assisted reproduction
- 1Reproductive Medicine Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, No.1095, Jiefang Road, Wuhan, 430030 China
Abstract
Background: Oocyte developmental competence depends not only on nuclear maturation but also on cytoplasmic functions required for fertilization and early embryogenesis. The endoplasmic reticulum (ER) is the major intracellular calcium store in mammalian oocytes and acts as a spatial organizer of cytoplasmic maturation. ER-associated features are increasingly discussed in relation to in vitro maturation, aging, cryopreservation, fertilization failure, and visible smooth endoplasmic reticulum aggregates, but their biological and clinical meanings are not always clearly understood.
Main body: This review integrates evidence on ER remodeling during oocyte maturation and its relevance to oocyte quality in assisted reproduction. During meiotic maturation, the ER undergoes stage- and species-specific reorganization that supports calcium-store positioning, inositol 1,4,5-trisphosphate receptor-dependent calcium release, and activation competence. ER remodeling during maturation is also linked to cytoskeletal organization, mitochondrial function, lipid handling, plasma-membrane Ca2+ influx, and degradative quality-control systems. These interfaces place ER remodeling within a broader multi-organelle network rather than a single calcium-signaling pathway. ER homeostasis and unfolded protein response (UPR) signaling contribute to cytoplasmic quality, whereas excessive ER stress can impair maturation through calcium imbalance, mitochondrial dysfunction, and defective stress adaptation. In clinical and laboratory settings, altered ER or smooth endoplasmic reticulum (SER)-related features may reveal cytoplasmic vulnerability after in vitro maturation, cryopreservation, aging, or fertilization failure, but they should not be interpreted as isolated or deterministic markers of oocyte competence.
Short conclusion: ER remodeling links oocyte maturation biology with several clinically relevant features of oocyte quality in assisted reproduction. Its translational value will depend on integrating structural observations, calcium-signaling competence, maturation history, and developmental endpoints while maintaining clear boundaries between mechanistic evidence and clinical decision-making.
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BibTeX
@article{zhou2026endoplasmic,
title = {{Endoplasmic reticulum remodeling in oocyte cytoplasmic maturation: calcium signaling, organelle communication, and clinical implications for assisted reproduction}},
author = {Juepu Zhou and Ruolin Mao and Lei Jin and Meng Wang},
journal = {Reproductive Biology and Endocrinology : RB\&E},
year = {2026},
month = jul,
doi = {10.1186/s12958-026-01600-6},
url = {https://doi.org/10.1186/s12958-026-01600-6},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Endoplasmic reticulum remodeling in oocyte cytoplasmic maturation: calcium signaling, organelle communication, and clinical implications for assisted reproduction
AU - Juepu Zhou
AU - Ruolin Mao
AU - Lei Jin
AU - Meng Wang
PY - 2026
DA - 2026/07/31
JO - Reproductive Biology and Endocrinology : RB&E
DO - 10.1186/s12958-026-01600-6
UR - https://doi.org/10.1186/s12958-026-01600-6
AB - Background: Oocyte developmental competence depends not only on nuclear maturation but also on cytoplasmic functions required for fertilization and early embryogenesis. The endoplasmic reticulum (ER) is the major intracellular calcium store in mammalian oocytes and acts as a spatial organizer of cytoplasmic maturation. ER-associated features are increasingly discussed in relation to in vitro maturation, aging, cryopreservation, fertilization failure, and visible smooth endoplasmic reticulum aggregates, but their biological and clinical meanings are not always clearly understood. Main body: This review integrates evidence on ER remodeling during oocyte maturation and its relevance to oocyte quality in assisted reproduction. During meiotic maturation, the ER undergoes stage- and species-specific reorganization that supports calcium-store positioning, inositol 1,4,5-trisphosphate receptor-dependent calcium release, and activation competence. ER remodeling during maturation is also linked to cytoskeletal organization, mitochondrial function, lipid handling, plasma-membrane Ca2+ influx, and degradative quality-control systems. These interfaces place ER remodeling within a broader multi-organelle network rather than a single calcium-signaling pathway. ER homeostasis and unfolded protein response (UPR) signaling contribute to cytoplasmic quality, whereas excessive ER stress can impair maturation through calcium imbalance, mitochondrial dysfunction, and defective stress adaptation. In clinical and laboratory settings, altered ER or smooth endoplasmic reticulum (SER)-related features may reveal cytoplasmic vulnerability after in vitro maturation, cryopreservation, aging, or fertilization failure, but they should not be interpreted as isolated or deterministic markers of oocyte competence. Short conclusion: ER remodeling links oocyte maturation biology with several clinically relevant features of oocyte quality in assisted reproduction. Its translational value will depend on integrating structural observations, calcium-signaling competence, maturation history, and developmental endpoints while maintaining clear boundaries between mechanistic evidence and clinical decision-making.
SN - 1477-7827
ER -