[Localization of the estrogen receptor alpha and beta-subtype in the nervous system, Hatschek's pit and gonads of amphioxus, Branchiostoma belcheri].

Immunocytochemical localization were investigated in the nervous system, wheel organ, Hatschek's pit and gonads of amphioxus using polyclonal antibodies against estrogen receptor-alpha and beta. The results revealed that ER-alpha and beta protein distributed in the above regions in larvae and adult at different developmental stages of both sexes. A major ER-alpha were expressed within nucleus of nerve cells, a few expressed in the cytoplasm and process as well as fiber of nerve cells in the forebrain, midbrain, hindbrain and nerve tube, while ER-beta were detected in the cytoplasm or on the cellular membrane, a few were within nucleus. ER-alpha immunopositive material distributed mainly in the nucleus of epithelial cells in the second layer of Hatschek's pit, a few were in the cytoplasm of upper layer epithelial cells, while ER-beta distributed in the nucleus of upper layer. In gonads, ER-alpha were distributed in the cytoplasm and nucleolus of oogonia and oocyte of small growth stage, germinal vesivle(nucleus) showed immunonegative reaction. In the large growth stage, strong immunopositive reaction were showed in nuclear membrane and nucleolus of oocyte, and within nucleus of mature egg cell in the mature stage. ER-beta immunopositive material distributed in the cytoplasm of oogonia and early oocytes as well as egg envelope of mature egg cell, the germinal vesicle showed immunonegative reaction. In testis, both ER subtype were localized in the cytoplasm of spermatogonia, primary and second spermatocyte as well as Sertoli cell, and within nucleus of spermatid cell, while spermatozoa showed immunonegative reaction. On the other hand, the results of double staining revealed that ER-alpha and beta numerously coexisted in a same cell, and fewly expressed in different cells in above regions. It is found for the first time that both estrogen receptor subtype, which mediated the regulate role of estrogen to neuroendocrine tissues in amphioxus, distributed extensively in amphiuoxus. The different localization of ER-alpha and beta receptor in the target cells suggests that the mediating estrogen signal line and the mechanism of gene transcription may be different.