Tissue and Cell 44 (2012) 95–100 Contents lists available at SciVerse ScienceDirect Tissue and Cell jou rn al h om epage: www.elsevier.com/locate/tice Immunolocalization of estrogen receptor  in Neomysis japonica oocytes and follicle cells during ovarian development Xiaozhen Yang a,1 , Liulan Zhao a,1 , Zhanzhong Zhao a,b,1 , Bing Hu a , Chun Wang a , Zhigang Yang a , Yongxu Cheng a,∗ a Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Shanghai 201306, China b Beijing Institute of Animal Husbandry and Veterinary Medicine, Chinese Academy of Agricultural Sciences, Beijing 100193, China a r t i c l e i n f o Article history: Received 20 June 2011 Received in revised form 2 December 2011 Accepted 2 December 2011 Available online 2 January 2012 Keywords: Estrogen receptor  Oocytes Follicle cells Immunohistochemistry Neomysis japonica a b s t r a c t Estrogen induces oocytes development and vitellogenesis in crustacean by interacting with estrogen receptor (ER) subtypes. In the present study, we detect for the first time the ER in oocytes and follicle cells and hepatopancreas cells of mysis by immunohistochemistry using a specific ER antibody. ER was mainly localized in the nuclei of oocytes and follicle cells, while mainly detected in nuclei of oogonia (OG), previtellogenic oocyte (PR) and endogenous vitellogenic oocyte (EN) at previtellogenic and early vitellogenic stage (I–early III). Follicle cells in all stages of ovary (all vitellogenic stages) showed strong ER positive reaction, and they were able to gradually move to oocytes during the development of oocytes. In addition, ER was also localized in the nuclei and cytoplasm of four hepatopancreas cells (including E-, R-, F- and B-cell) in all ovary stages. These findings suggest, for the first time to our knowledge, that there could be a close link between oogenesis, follicle cells, hepatopancreas cells and endocrine regulation, and estrogens might be involved in the regulation of oocytes at early ovarian stage in mysis. Crown Copyright © 2011 Published by Elsevier Ltd. All rights reserved. 1. Introduction The estrogen receptors (ERs) are members of the nuclear recep- tor superfamily, which is a transcription factor that directly binds to a specific DNA sequence, the estrogen responsive element and regulates the transactivation of estrogen target genes such as vitel- logenin (Vg) (Matsumotol et al., 2007). The discovery of multiple estrogen receptor isotypes (alpha and beta) adds another level of complexity to the ER mediated pathway of gene regulation (Sabo- Attwood et al., 2004). ER and ER can be detected in a broad spectrum of tissues in mammals (Takeshi et al., 2008). In some organs, both ER subtypes are expressed at similar levels, whereas in others, ER or ER predominate. In addition, both ER subtypes may be present in the same tissue, but in different cell types (Karin et al., 2006; Weihua et al., 2003). ER is expressed predominantly in the ovary and prostate, while the highest levels of expression for ER are seen in the epididymis, testis, ovary, and uterus (Drummond et al., 1999). ER- is thought to mediate many of estrogen’s actions in a variety of reproductive tissues, including the ovary (Walters, ∗ Corresponding author at: Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, No. 999 Huchenghuan Road, Shanghai 201306, China. Tel.: +86 21 61900417; fax: +86 21 61900405. E-mail address: yxcheng@shou.edu.cn (Y. Cheng). 1 These authors contributed equally to this work. 1985). ER- protein should be present at a detectable level in the ovary and elimination of the ER- gene in vivo, which could disrupt all ovarian functions requiring estrogen action, such as folliculoge- nesis (Tatiane et al., 2010). While the present of ER in aquaculture species have been studied, to date, little attention has been paid to aquatic animals that naturally exist in aquatic systems, which are sensitive to endocrine disrupting chemicals (EDCs), such as mysis. There is now unequivocal evidence that a wide variety of EDCs that enter the aquatic environment are capable of disrupt- ing endocrine function in wildlife and humans (IEH, 1999). Some of EDCs are able to mimic the behavior of natural endogenous estrogens. And they are suspected of being responsible for an increase in the disruption of the normal physiological functions of the endocrine systems of mammals, fish, birds, reptiles and invertebrates (Golden et al., 1998; Tyler et al., 1998). Although invertebrates comprise over 95% of the known species in the animal kingdom, most research regarding endocrine disruption in wildlife has been skewed in favor of vertebrates. One possible reason for this discrepancy in focus is that the endocrinology of invertebrates is less well understood than that of vertebrates (DeFur et al., 1999; Depledge and Billinghurst, 1999). In invertebrates, estrogens were described in crustaceans as early as 1940 by Donahue. Later, estrogens have been detected in some other invertebrates, such as the eastern mud snail, Ilyanassa obsolete (Sternberg et al., 2008), the oyster Crassostrea gigas (Matsumoto et al., 2007), the mud crab Scylla serrata (Warrier 0040-8166/$ – see front matter. Crown Copyright © 2011 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.tice.2011.12.001