Complex sentence: In rats, low-level exposure during development to chlorpyrifos has its greatest neurotoxic effects during a window in which sex differences in the brain develops, and exposure leads to reductions or reversals of normal rat male-female differences.
Split into simpler sentences: In rats, low-level exposure during development to chlorpyrifos has its greatest neurotoxic effects during a window in which sex differences in the brain develop, leading to sex-specific responses to exposure. After exposure during this period, there are reductions or reversals of normal rat male-female differences.