In vitro exposure to benzo[a]pyrene damages the developing mouse ovary

Area of Science:

• Reproductive toxicology
• Developmental biology
• Ovarian toxicology

Background:

• Females possess a finite ovarian reserve established during fetal development.
• Maternal exposure to reproductive toxicants can impair future fertility.
• Benzo[a]pyrene (B[a]P) from cigarette smoke is a known ovotoxicant, with significant smoking rates during pregnancy.

Purpose of the Study:

• To investigate the impact of B[a]P exposure on the developing ovary.
• To utilize a mouse model for in vitro and in vivo experiments.
• To assess B[a]P effects before and after follicle formation.

Main Methods:

• Exposure of fetal mouse ovaries to B[a]P before follicle formation.
• Exposure of neonatal mouse ovaries to B[a]P after follicle formation.
• Assessment of germ cell number, DNA damage, meiotic progression, follicle count, apoptosis, and somatic cell proliferation.

Main Results:

• Pre-follicle formation B[a]P exposure reduced germ cells and primordial follicles by up to 76%, increasing DNA double-strand breaks.
• Post-follicle formation B[a]P exposure reduced healthy follicles by 85%, increasing apoptosis and decreasing somatic cell proliferation.
• No statistically significant increase in oxidative stress was observed, and melatonin did not protect against B[a]P-induced damage.

Conclusions:

• B[a]P exposure damages the developing ovary both before and shortly after follicle formation.
• This damage to the ovarian reserve can lead to a subsequent decrease in fertility.
• Findings highlight the risks of maternal exposure to environmental toxicants on female reproductive health.