Synaptonemal complex damage in fetal mouse oocytes induced by ionizing irradiation

Area of Science:

• Reproductive biology
• Radiation biology
• Developmental biology

Background:

• Oocyte quality is crucial for female fertility.
• Fetal oocytes are vulnerable to environmental insults, including radiation.
• Understanding radiation effects on developing oocytes is vital for risk assessment.

Purpose of the Study:

• To investigate the effects of ionizing irradiation on fetal mouse oocytes.
• To determine the impact of irradiation timing on oocyte nuclear integrity.
• To assess potential links between radiation-induced oocyte damage and fertility outcomes.

Main Methods:

• Fetal female mice were exposed to a single 2 Gy dose of ionizing radiation on gestation days 14, 16, or 17.
• Synaptonemal complexes of primary oocytes were analyzed on day 17 of gestation.
• Oocyte morphology, including atretic cell counts and synaptonemal complex fragmentation, was evaluated.

Main Results:

• Irradiation on day 14 led to increased atretic cells.
• Irradiation on days 16 and 17 significantly increased synaptonemal complex fragmentation.
• No significant changes in multivalent formation or univalent frequencies were observed.
• Observed nuclear lesions suggest potential for reduced fertility and chromosome malsegregation.

Conclusions:

• The timing of ionizing radiation exposure during fetal development influences the type and severity of oocyte damage.
• Damage to synaptonemal complexes in fetal oocytes is a key concern following irradiation.
• Radiation-induced nuclear lesions in fetal oocytes may have long-term consequences for reproductive health.