Résumé
To evaluate effects of in utero and lactational 2,3,7,8-tetrachlorodibenzo-rho-dioxin [TCDD] exposure on the reproductive function in female rat offspring, before and after puberty. The pregnant Sprague Dawely rat administered 0, or 1.0 rag TCDD/kg on Gestation Day [GD] 8 and 15. Female offspring were examined at the post-weanling before puberty on posnatal day [PND] 21 and in young adult stage of development on PND42. Ovulation assessment, radioimmunoassay for serum gonadotropins, steroids and histo-morphmetric analysis to the ovaries were evaluated. The analysis included a count, measurement and classification of preantral and antral follicles throughout the entire ovary on PND 21. The results indicate that TCDD treatment significantly reduced the ovulation rate, serum gonadotropins, steroids levels and the number of antral and preantral follicles of certain size classes. The histopathological examination revealed small preovulatory follicles displaying an atretic morphologic difference among the ovaries of rats exposed to TCDD treatments. These data support the hypothesis that TCDD results in adverse effects on female reproductive function. However, the age of animals before or after puberty play an important role in the difference between results. Moreover, TCDD exposure on the GD 8 or 15 has a great concern in the results observed