Expression of estrogen receptors in the dorsal root ganglia of the chick embryo

Estrogen receptors (ER) are widely distributed in the central nervous syste m (CNS). Recent studies, to date in rat only, have shown that ER are also e xpressed in neurons of the dorsal root panglia (DRG) where they appear to h ave functional roles. However, no data yet exists about estrogen receptors in the embryonic DRC. In the present study, immunocytochemical staining for ER in the DRC; of chick embryos from day 6.5 to 18.5 (Hamburger and Hamilt on St. 30-45) of incubation was performed. ER+ cells were first consistentl y observed at day 8.5 (St. 34), more concentrated in the ventral-lateral po rtion of the DRG. From day 8.5 to 12.5 (St. 38), the density of ER+ cells a nd the staining intensity increased, with no obvious changes from day (E) 1 2.5 to 18.5. Although ER is detected mainly in the cytoplasm of embryonic D RG neurones, ER+ cells with nuclear staining are sometimes observed and gra dually increase in number during development. ER-immunoreactivity in the DR G at cervical, thoracic and lumbo-sacral levels is similar and no obvious d ifferences in staining were observed between male and female embryos. ER+ n eurons are also present in the sympathetic ganglia from E8.5 and some prima ry spinal motoneurons are ER+ beginning at E14.5. The results suggest that estrogen may play a role in the embryonic development of the DRG. (C) 2000 Elsevier Science B.V. All rights reserved.