Effects of Simulated Microgravity In Vitro on Human Metaphase II Oocytes: An Electron Microscopy-Based Study.

Area of Science:

• Reproductive biology
• Space biology
• Cellular ultrastructure

Background:

• Earth's gravity influences biological processes; microgravity in space causes adverse health effects in astronauts.
• Observed negative impacts of microgravity on reproductive functions, including suppressed menstrual cycles and effects on gametes and early embryos.
• Limitations in space flight studies necessitate the use of microgravity simulators for in vitro research.

Purpose of the Study:

• To investigate the in vitro effects of simulated microgravity on the ultrastructural features of human metaphase II oocytes.
• To assess the potential impact of altered gravity on oocyte quality and cellular components.

Main Methods:

• Utilized a Random Positioning Machine (RPM) to simulate microgravity conditions.
• Performed Transmission Electron Microscopy (TEM) analysis on human metaphase II oocytes exposed to simulated microgravity.

Main Results:

• Microgravity exposure altered the localization of mitochondria and cortical granules, suggesting cytoskeleton involvement.
• Observed changes in mitochondria and smooth endoplasmic reticulum (SER) morphology, forming mitochondria-vesicle complexes instead of SER aggregates.
• Demonstrated potential compromise in oocyte quality due to microgravity-induced ultrastructural changes.

Conclusions:

• Simulated microgravity negatively affects human oocyte quality by interfering with essential morphodynamic events.
• Microgravity may disrupt the cytoskeleton, mitochondria, and endoplasmic reticulum, impacting the oocyte's ability to achieve and maintain fertilization competence.
• In vitro microgravity models are valuable for studying cellular responses to altered gravity environments.