PARENT SESSION
PT2 - Endocrine Disruption
Tuesday, 19 November 2002
8:00 AM to 6:30 PM
Exhibit Hall

(P566) Histological Changes in Gonadal Development in Chickens Exposed to 17B-Estradiol.

Grasman, Keith¹, Reaves, M. Elissa^*,1, ¹ Wright State University, Dayton, OH, USA

ABSTRACT- Reproductive abnormalities such as ovotestes and nodules in the testes have been observed in Great Lakes seabirds. These birds were exposed to contaminants including organochlorines and possibly estrogenic chemicals. Estrogenic chemicals may alter the cellular organization of gonads of birds. Therefore, 17B-estradiol (E2) and tamoxifen, an estrogen receptor blocker, were used to determine whether developmental E2 exposure would alter the histological structure of the gonads and examine if tamoxifen could block E2 effects. Chicken eggs were injected with E2 (50g/egg), tamoxifen (10, 50 ng/g egg) or a combination of both on day 0 of incubation. On day 20 of incubation, gonads were fixed in formalin, embedded in Spurrs epoxy, sectioned, and stained with toluidine for histological examination. Males with feminized, or flattened left testes were greatest in E2 males (27%) with decreased rates in E2 + tamoxifen males (25% and 21%). Protruding seminiferous tubules from the testis were observed in E2 (27%), E2 + tamoxifen (6% and 14%), and tamoxifen only males (17%, and 6%). Neither feminized testes nor protruding tubules were observed in control males. Histological analyses revealed normal testicular development, such as Sertoli density and medulla area. Residual right ovaries occurred 0% in controls, 33% in E2 females, 33% and 17% in E2 + tamoxifen (10, 50), and 42% and 36% in tamoxifen (10, 50) only females, respectively. Histological analyses revealed increased cortical area and decreased stromal area of E2 females (p=0.02). Tamoxifen did not reduce E2 effects on the ovarian cortex. At this dose E2 did not cause the development of testicular nodules as seen in herring gulls of the Great Lakes. However, estrogen modulated the early development of the ovaries, with tamoxifen sometimes reducing E2 effects.

Key words: chicken, 17B-estradiol, tamoxifen, histology