Mouse zona pellucida dynamically changes its elasticity during oocyte maturation, fertilization and early embryo...

Area of Science:

• Reproductive Biology
• Developmental Biology
• Biophysics

Background:

• The zona pellucida is a crucial outer layer of mammalian oocytes and early embryos.
• Understanding zona pellucida's mechanical properties is vital for reproductive research and assisted reproductive technologies.
• Changes in zona pellucida elasticity during development are not fully characterized.

Purpose of the Study:

• To quantitatively assess the elasticity of the mouse zona pellucida throughout oocyte maturation, fertilization, and early embryonic development.
• To investigate the dynamic changes in zona pellucida mechanical properties.
• To evaluate the safety and efficacy of a micro tactile sensor for these measurements.

Main Methods:

• Quantitative measurement of Young's modulus using a highly sensitive micro tactile sensor (MTS).
• Utilized a specialized chamber for precise measurements on oocytes and embryos.
• Measured elasticity across various developmental stages: germinal vesicle (GV), metaphase-II (MII), pronuclear (PN), 2-cell, 4-cell, 8-cell, morula (M), and early blastocyst (EB).

Main Results:

• Zona pellucida elasticity significantly changed during development, with Young's modulus values varying across stages.
• A distinct hardening of the zona pellucida was observed following fertilization (PN stage).
• This hardening was transient, with the zona pellucida gradually softening as embryonic development progressed from the PN to the early blastocyst stage.

Conclusions:

• Mouse zona pellucida elasticity undergoes dynamic alterations crucial for early development.
• Fertilization induces a temporary hardening of the zona pellucida, which is reversed during subsequent embryonic development.
• The micro tactile sensor provides a safe and sensitive method for evaluating zona pellucida biomechanics.