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(T/MF206) Spermatogenesis during the annual reproductive cycle in intersex flounder from the Seine Bay. Gallien, Isabelle1, Minier, Christophe1, Tutundjian, Renaud1, Bocquené, Gilles2, Leboulenger, Francois1, 1 2 ABSTRACT- In recent years, there has been worldwide concern over the possibility that some environmentally persistent chemicals can disrupt the reproductive and endocrine system of humans and wildlife by mimicking the action of natural steroid hormones. One of the potentially most deleterious reproductive effects observed in wildlife has been the high incidence of feminised male fish (intersex fish) caught downstream of sewage treatment works. This feminisation is accompanied by elevated vitellogenin content in plasma, suggesting that both phenomenon have common cause. Consequences of these abnormalities for fish population are only speculative. In order to study whether intersex fish show a normal gametogenesis, flounders (Plathychthys flesus) from the Seine Bay were sampled monthly from May 1999. Gonads were examined by histology and the relative frequency of the testicular phases were recorded in males to provide a detailed description of spermatogenesis of the flounder in the study area. Seven percent of male fish were identified as intersex and characterised either by only a few isolated primary oocytes dispersed among male tissue or by the development of two separated regions with either male or female cellular types depending on the reproductive phase. The gametogenesis stages of the intersex fish were compared with those observed in other male fish caught at the same time. All intersex fish were synchronous and appeared to successfully produce spermatozoids. Other indices such as variations in GSI, HSI and plasma vitellogenin content will be discussed in relation with the annual reproductive cycle. Key words: flounder, spermatogenesis, endocrine disruption |
