Decreased number of sperms and Sertoli cells in mature rats exposed to diesel exhaust as fetuses.

This study was conducted to follow up the effects of fetal exposure to diesel exhaust on testicular cell numbers and daily sperm production in adulthood. Thirty-six pregnant rats were divided into five groups: groups exposed to total diesel-engine exhaust containing 1.71 mg/m3 particulate matter and 0.80 ppm nitrogen dioxide (high dose) or 0.17 mg/m3 particulate matter and 0.10 ppm nitrogen dioxide (low dose); groups exposed to filtered exhaust without particles containing 0.80 (high dose) or 0.10 (low dose) ppm nitrogen dioxide; and a group exposed to clean air. Exhaust exposure was performed from gestational day 7 to delivery. The numbers of daily produced sperm, spermatids and Sertoli cells in the diesel-exhaust-exposed groups were significantly lower than those in the control group on day 96 after birth. The ratio of spermatids/Sertoli cells and the follicle-stimulating hormone levels in the exposed groups were significantly higher. The present study provides evidence for the first time that mature rats exposed to diesel exhaust during fetus show a decrease in the daily production of sperm due to an insufficient number of Sertoli cells. As both the exhaust-exposed groups showed almost the same reactions toward the inhalation, the gaseous phase must have included the responsible toxicants.