Histological changes in immune and endocrine organs of quail embryos: Exposure to estrogen and nonylphenol

Effects of 17β-estradiol and p-nonylphenol were examined in the immune and endocrine organs of Japanese quail embryos. The test compounds were injected into the yolk of embryonated eggs. Injection of estrogen resulted in (1) disappearance of lymphoid cells and flattened development of plicae in the bursa of Fabricius, (2) decreased area of thyroid follicles and height of simple cuboidal epithelial cells in the thyroid, (3) increased follicular appearance of the thymus, and (4) development of an ovotestis in male embryos. Injection of nonylphenol did not induce flattened plicae in the bursa of Fabricius or development of an ovotestis in male embryos, but it increased the disappearance of lymphoid cells from the lymphoid follicles in the bursa, decreased the height of simple cuboidal epithelial cells surrounding the thyroid follicle, and increased the follicle-like structure in the thymus in male embryos. These results suggest that nonylphenol has estrogenic effects, but these are low compared to those of estrogen itself.