Abstract
Vol.43 No.2
- « prev
- ↑Table of Contents
- next »
Original
Extracellular Ca2+ and cortical actin dynamics contribute to the maintenance of plasma membrane integrity in mouse oocytes under hyperosmotic stress
JMOR, 43(2) 125-133, 2026
Mammalian oocytes are exposed to substantial osmotic stress during assisted reproductive procedures, yet the mechanisms that preserve plasma membrane integrity under these conditions remain poorly understood. In this study, we examined whether hyperosmotic stress affects plasma membrane integrity in mouse MII oocytes and assessed the contributions of extracellular Ca2+ and cortical F-actin. Oocytes were exposed to sucrose solutions, and membrane permeability, cortical actin organization, and the effects of actin polymerization inhibition were evaluated. Sucrose induced concentration-dependent shrinkage: oocyte viability was maintained up to 750 mM but declined at 1,000 mM. In Ca2+-free medium, exposure to 750 mM sucrose significantly increased propidium iodide uptake, indicating increased membrane permeability; however this increase was suppressed in the presence of extracellular Ca2+. Hyperosmotic stress decreased cytoplasmic F-actin fluorescence intensity and increased cortical F-actin thickness only in Ca2+-containing medium. Furthermore, inhibition of actin polymerization with latrunculin A increased membrane permeability under hyperosmotic conditions. These findings suggest that extracellular Ca2+ and cortical actin dynamics contribute to the maintenance of plasma membrane integrity in mouse MII oocytes exposed to hyperosmotic stress.
