PT07 Chemical and Biological Analysis of Endocrine Disrupting Compounds
Exhibit Hall
8:00 AM - Tuesday
(PT120) Ecological relevance of testis-ova and its quantitative evaluation method: a new detection method for testis-ova in medaka.
LIN, BL1, HAGINO, S2, KAGOSHIMA, M2, ASHIDA, S2, IWAMATSU, T3, TOKAI, A1, NAKANISHI, J1, 1 Recearch Center for Chemical Risk Management, National Institute of Advanced Industrial Science and Technology, 16-1 Onogawa, Tsukuba 305-8569, JAPAN2 Sumika Technoservice Corporation, 2-1 Takatsukasa, 4-chome, Takarazuka 665-0051, JAPAN3 Aichi University of Education, 16 Terayamashita, Igaya-cho, Kariya 448-0001, JAPAN
ABSTRACT- A new quantitative evaluation technique called the fragmented method* for the detection of testis-ova in male fish using a medaka (Oryzias latipes) S-rR strain has been developed in this study. A current histological method is still being applied to detect the testis-ova in male fish exposed to estrogens or suspected endocrine-disrupting chemicals, even though some disadvantages, such as oversight of the testis-ova due to the limited observation area of the testis, are apparently indicated. The method we developed here enables the accurate determination of the number and the developmental stages (size) of oocytes in a whole testis. The testis was removed from the specimen, fixed with 10% buffered formalin solution and broken into small fragments with a dissecting needle and aciform forceps in glycelin solution containing a small amount of methylene blue or toluidine blue on a slide glass. All developing oocytes of various sizes were clearly stained and thereby were observable under a dissecting microscope. Spermatozoa were also distinguishable in this method. In conclusion, this method is not only proven as a convenient and cost-effective method for quantitatively detecting testis-ova appearance in fish, but is also expected to contribute to the understanding of testis-ova appearance and its biological significances to future studies of endocrine disruption.
Key words: medaka, testis-ova quantitative evaluation , endocrine disruption, histological method