{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,29]],"date-time":"2026-07-29T05:12:31Z","timestamp":1785301951879,"version":"3.55.0"},"reference-count":55,"publisher":"Oxford University Press (OUP)","issue":"5","license":[{"start":{"date-parts":[[2010,1,21]],"date-time":"2010-01-21T00:00:00Z","timestamp":1264032000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/pages\/standard-publication-reuse-rights"},{"start":{"date-parts":[[2010,1,21]],"date-time":"2010-01-21T00:00:00Z","timestamp":1264032000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["setac.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2010,1,21]]},"abstract":"<jats:title>Abstract<\/jats:title>\n               <jats:p>The natural estrogen 17 \u03b2-estradiol (E2) is a potential environmental contaminant commonly employed as a positive control substance in bioassays involving estrogenic effects. The aquatic anuran Xenopus laevis is a frequent subject of reproductive endocrine disruptor research; however, histopathological investigations have tended to be less than comprehensive. Consequently, a study was designed to characterize gross and microscopic changes in the gonads of X. laevis as a result of E2 exposure. Additional goals of this study, which consisted of three separate experiments, included the standardization of diagnostic terminology and criteria, the validation of statistical methodology, and the establishment of a half maximal effective concentration (EC50) for E2 as defined by an approximately 50% conversion of presumptive genotypic males to phenotypic females. In the first experiment, frogs were exposed to nominal concentrations of 0, 0.2, 1.5, or 6.0\u2009\u00b5g\/L E2. From these experimental results and those of a subsequent range finding trial, the EC50 for E2 was determined to be approximately 0.2\u2009\u00b5g\/L. This E2 concentration was utilized in the other two experiments, which were performed at different facilities to confirm the reproducibility of results. Experiments were conducted according to Good Laboratory Practice guidelines, and the histopathologic evaluations were peer reviewed by an independent pathologist. Among the three trials, the histopathological findings that were strongly associated with E2-exposure (p\u2009&amp;lt;\u20090.001 to 0.0001) included an increase in the proportion of phenotypic females, mixed sex, dilated testis tubules, dividing gonocytes in the testis, and dilated ovarian cavities in phenotypic ovaries. A comparison of the gross and microscopic evaluations suggested that some morphologic changes in the gonads may potentially be missed if studies rely entirely on macroscopic assessment. Environ. Toxicol. Chem. 2010;29:1091\u20131105. \u00a9 2010 SETAC<\/jats:p>","DOI":"10.1002\/etc.133","type":"journal-article","created":{"date-parts":[[2010,3,5]],"date-time":"2010-03-05T00:14:26Z","timestamp":1267748066000},"page":"1091-1105","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":22,"title":["Effects of 17 \u03b2-estradiol exposure on <i>Xenopus laevis<\/i> gonadal histopathology"],"prefix":"10.1093","volume":"29","author":[{"given":"Jeffrey C.","family":"Wolf","sequence":"first","affiliation":[{"name":"Experimental Pathology Laboratories, P.O. Box 169, Sterling, Virginia, USA 20167"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ilka","family":"Lutz","sequence":"additional","affiliation":[{"name":"Leibniz-Institute of Freshwater Ecology & Inland Fisheries, M\u00fcggelseedamm 310, D12587 Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Werner","family":"Kloas","sequence":"additional","affiliation":[{"name":"Humboldt University, Unter den Linden 6, D-10099 Berlin, Germany"},{"name":"Leibniz-Institute of Freshwater Ecology & Inland Fisheries, M\u00fcggelseedamm 310, D12587 Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Timothy A.","family":"Springer","sequence":"additional","affiliation":[{"name":"Wildlife International, 8598 Commerce Drive, Easton, Maryland, USA 21601"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Larry R.","family":"Holden","sequence":"additional","affiliation":[{"name":"Sielken & Associates Consulting, 3833 Texas Avenue, Suite 230, Bryan Texas, USA 77802"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Henry O.","family":"Krueger","sequence":"additional","affiliation":[{"name":"Wildlife International, 8598 Commerce Drive, Easton, Maryland, USA 21601"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alan J.","family":"Hosmer","sequence":"additional","affiliation":[{"name":"Syngenta Crop Protection, P.O. Box 18300, Greensboro NC, USA 27419"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2010,1,21]]},"reference":[{"key":"2025010316451323100_bib1","doi-asserted-by":"crossref","first-page":"515","DOI":"10.1016\/S0887-2333(03)00121-8","article-title":"Endocrine disruptors: Effects on male fertility and screening tools for their assessment","volume":"17","author":"Eertmans","year":"2003","journal-title":"Toxicol In Vitro"},{"key":"2025010316451323100_bib2","doi-asserted-by":"crossref","first-page":"49","DOI":"10.1016\/S0048-9697(99)80016-3","article-title":"Amphibians as a model to study endocrine disruptors: I. Environmental pollution and estrogen receptor binding","volume":"225","author":"Lutz","year":"1999","journal-title":"Sci Total Environ"},{"key":"2025010316451323100_bib3","doi-asserted-by":"crossref","first-page":"6537","DOI":"10.1021\/es0607739","article-title":"Fate, transport, and biodegradation of natural estrogens in the environment and engineered systems","volume":"40","author":"Khanal","year":"2006","journal-title":"Environ Sci Technol"},{"key":"2025010316451323100_bib4","doi-asserted-by":"crossref","first-page":"5471","DOI":"10.1021\/es034410+","article-title":"Manure-borne estrogens as potential environmental contaminants: A review","volume":"37","author":"Hanselman","year":"2003","journal-title":"Environ Sci Technol"},{"key":"2025010316451323100_bib5","doi-asserted-by":"crossref","first-page":"160","DOI":"10.1016\/j.ecoenv.2004.10.010","article-title":"Effects of atrazine on metamorphosis, growth, laryngeal and gonadal development, aromatase activity, and sex steroid concentrations in Xenopus laevis","volume":"62","author":"Coady","year":"2005","journal-title":"Ecotoxicol Environ Saf"},{"key":"2025010316451323100_bib6","doi-asserted-by":"crossref","first-page":"1996","DOI":"10.1897\/03-450","article-title":"Plasma sex steroid concentrations and gonadal aromatase activities in African clawed frogs (Xenopus laevis) from South Africa","volume":"23","author":"Hecker","year":"2004","journal-title":"Environ Toxicol Chem"},{"key":"2025010316451323100_bib7","doi-asserted-by":"crossref","first-page":"273","DOI":"10.1093\/toxsci\/kfi203","article-title":"Effects of atrazine on CYP19 gene expression and aromatase activity in testes and on plasma sex steroid concentrations of male African clawed frogs (Xenopus laevis)","volume":"86","author":"Hecker","year":"2005","journal-title":"Toxiol Sci"},{"key":"2025010316451323100_bib8","doi-asserted-by":"crossref","first-page":"559","DOI":"10.1016\/S1096-4959(02)00162-8","article-title":"Functional genomics and sexual differentiation in amphibians","volume":"133","author":"B\u00f6gi","year":"2002","journal-title":"Comp Biochem Physiol B"},{"key":"2025010316451323100_bib9","first-page":"310","article-title":"Endocrine disrupting chemicals (EDC) with (anti)estrogenic and (anti)androgenic modes of action affecting reproductive biology of Xenopus laevis: I. Effects on sex steroid levels and biomarker expression","volume":"144","author":"Urbatzka","year":"2007","journal-title":"Comp Biochem Phys C"},{"key":"2025010316451323100_bib10","doi-asserted-by":"crossref","first-page":"149","DOI":"10.1016\/j.jsbmb.2007.01.007","article-title":"Analysis of the p450 aromatase gene expression in the Xenopus brain and gonad","volume":"107","author":"Iwabuchi","year":"2007","journal-title":"J Steroid Biochem Mol Biol"},{"key":"2025010316451323100_bib11","doi-asserted-by":"crossref","first-page":"280","DOI":"10.1016\/j.ygcen.2007.01.041","article-title":"Aromatase, steroid-5-alpha-reductase type 1 and type 2 mRNA expression in gonads and in brain of Xenopus laevis during ontogeny","volume":"153","author":"Urbatzka","year":"2007","journal-title":"Gen Comp Endocrinol"},{"key":"2025010316451323100_bib12","doi-asserted-by":"crossref","first-page":"236","DOI":"10.1016\/j.ecoenv.2005.07.018","article-title":"All ZZ male Xenopus laevis provides a clear sex-reversal test for feminizing endocrine disruptors","volume":"63","author":"Oka","year":"2006","journal-title":"Ecotoxicol Environ Saf"},{"key":"2025010316451323100_bib13","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1016\/j.aquatox.2008.02.009","article-title":"Effect of atrazine on metamorphosis and sexual differentiation in Xenopus laevis","volume":"87","author":"Oka","year":"2008","journal-title":"Aquat Toxicol"},{"key":"2025010316451323100_bib14","doi-asserted-by":"crossref","first-page":"1748","DOI":"10.1248\/bpb.28.1748","article-title":"Effects of nonylphenol and triclosan on production of plasma vitellogenin and testosterone in male South African clawed frogs (Xenopus laevis)","volume":"28","author":"Matsumura","year":"2005","journal-title":"Biol Pharm Bull"},{"key":"2025010316451323100_bib15","doi-asserted-by":"crossref","first-page":"250","DOI":"10.1016\/j.aquatox.2005.12.014","article-title":"Xenopus laevis is a potential alternative model animal species to study reproductive toxicity of phytoestrogens","volume":"77","author":"Cong","year":"2006","journal-title":"Aquat Toxicol"},{"key":"2025010316451323100_bib16","doi-asserted-by":"crossref","first-page":"102","DOI":"10.1016\/S0013-9351(03)00086-0","article-title":"Bisphenol A induces feminization in Xenopus laevis tadpoles","volume":"94","author":"Levy","year":"2004","journal-title":"Environ Res"},{"key":"2025010316451323100_bib17","doi-asserted-by":"crossref","first-page":"223","DOI":"10.1016\/S0045-6535(03)00308-4","article-title":"Assessing chronic toxicity of bisphenol A to larvae of the African clawed frog (Xenopus laevis) in a flow-through exposure system","volume":"53","author":"Pickford","year":"2003","journal-title":"Chemosphere"},{"key":"2025010316451323100_bib18","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1016\/S0048-9697(99)80017-5","article-title":"Amphibians as a model to study endocrine disruptors: II. Estrogenic activity of environmental chemicals in vitro and in vivo","volume":"225","author":"Kloas","year":"1999","journal-title":"Sci Total Environ"},{"key":"2025010316451323100_bib19","doi-asserted-by":"crossref","first-page":"396","DOI":"10.1897\/1551-5028(2003)022<0396:ROLXLT>2.0.CO;2","article-title":"Response of larval Xenopus laevis to atrazine: Assessment of growth, metamorphosis, and gonadal and laryngeal morphology","volume":"22","author":"Carr","year":"2003","journal-title":"Environ Toxicol Chem"},{"key":"2025010316451323100_bib20","doi-asserted-by":"crossref","first-page":"941","DOI":"10.1080\/15287390490443722","article-title":"Effects of atrazine on metamorphosis, growth, and gonadal development in the green frog (Rana clamitans)","volume":"67","author":"Coady","year":"2004","journal-title":"J Toxicol Env Heal A"},{"key":"2025010316451323100_bib21","doi-asserted-by":"crossref","first-page":"5476","DOI":"10.1073\/pnas.082121499","article-title":"Hermaphroditic, demasculinized frogs after exposure to the herbicide atrazine at low ecologically relevant doses","volume":"99","author":"Hayes","year":"2002","journal-title":"Proc Natl Acad Sci USA"},{"key":"2025010316451323100_bib22","doi-asserted-by":"crossref","first-page":"568","DOI":"10.1289\/ehp.5932","article-title":"Atrazine-induced hermaphroditism at 0.1\u2009ppb in American leopard frogs (Rana pipiens): Laboratory and field evidence","volume":"111","author":"Hayes","year":"2003","journal-title":"Environ Health Perspect"},{"key":"2025010316451323100_bib23","doi-asserted-by":"crossref","first-page":"134","DOI":"10.1289\/ehp.8067","article-title":"Characterization of atrazine-induced gonadal malformations in African clawed frogs (Xenopus laevis) and comparisons with effects of an androgen antagonist (cyproterone acetate) and exogenous estrogen (17 \u03b2-estradiol): Support for the demasculization\/feminization hypothesis","volume":"114","author":"Hayes","year":"2006","journal-title":"Environ Health Perspect"},{"key":"2025010316451323100_bib24","first-page":"241","article-title":"Endocrine disrupting chemicals (EDC) with (anti)estrogenic and (anti)androgenic modes of action affecting reproductive biology of Xenopus laevis: II. Effects on gonad histomorphology","volume":"147","author":"Cevasco","year":"2008","journal-title":"Comp Biochem Phys C"},{"key":"2025010316451323100_bib25","doi-asserted-by":"crossref","first-page":"5255","DOI":"10.1021\/es048134q","article-title":"Gondal development of larval male Xenopus laevis exposed to atrazine in outdoor microcosms","volume":"39","author":"Jooste","year":"2005","journal-title":"Environ Sci Technol"},{"key":"2025010316451323100_bib26","doi-asserted-by":"crossref","first-page":"2466","DOI":"10.1897\/02-173","article-title":"Gonadal differentiation in frogs exposed to estrogenic and antiestrogenic compounds","volume":"22","author":"MacKenzie","year":"2003","journal-title":"Environ Toxicol Chem"},{"key":"2025010316451323100_bib27","doi-asserted-by":"crossref","first-page":"65","DOI":"10.1897\/05-136R.1","article-title":"Effects of nitrate and atrazine on larval development and sexual differentiation in the northern leopard frog Rana pipiens","volume":"25","author":"Orton","year":"2006","journal-title":"Environ Toxicol Chem"},{"key":"2025010316451323100_bib28","doi-asserted-by":"crossref","first-page":"2027","DOI":"10.1897\/04-227R.1","article-title":"Effects of the synthetic estrogen ethinylestradiol on the early life stages of mink frogs and green frogs in the wild and in situ","volume":"24","author":"Park","year":"2005","journal-title":"Environ Toxicol Chem"},{"key":"2025010316451323100_bib29","doi-asserted-by":"crossref","first-page":"356","DOI":"10.1016\/j.aquatox.2006.07.004","article-title":"Persistent sex-reversal and oviducal agenesis in adult Xenopus (Silurana) tropicalis frogs following larval exposure to the environmental pollutant ethynylestradiol","volume":"79","author":"Pettersson","year":"2006","journal-title":"Aquat Toxicol"},{"key":"2025010316451323100_bib30","doi-asserted-by":"crossref","first-page":"16","DOI":"10.1016\/j.chroma.2006.04.001","article-title":"Amphibians as model to study endocrine disruptors","volume":"1130","author":"Kloas","year":"2006","journal-title":"J Chromatogr A"},{"key":"2025010316451323100_bib31","doi-asserted-by":"crossref","first-page":"230","DOI":"10.1016\/j.aquatox.2005.09.010","article-title":"Atrazine concentrations, gonadal gross morphology and histology in ranid frogs collected in Michigan agricultural areas","volume":"76","author":"Murphy","year":"2006","journal-title":"Aquat Toxicol"},{"key":"2025010316451323100_bib32","doi-asserted-by":"crossref","first-page":"721","DOI":"10.1080\/10408440802116496","article-title":"Effects of atrazine on fish, amphibians, and aquatic reptiles: A critical review","volume":"38","author":"Solomon","year":"2008","journal-title":"Crit Rev Toxicol"},{"key":"2025010316451323100_bib33","first-page":"103","article-title":"Terminology of gonadal anomalies in fish and amphibians resulting from chemical exposures","volume":"187","author":"Hecker","year":"2006","journal-title":"Rev Environ Contam Toxicol"},{"key":"2025010316451323100_bib34","doi-asserted-by":"crossref","first-page":"376","DOI":"10.1093\/toxsci\/kfn232","article-title":"Does atrazine influence larval development and sexual differentiation in Xenopus laevis?","volume":"107","author":"Kloas","year":"2009","journal-title":"Toxicol Sci"},{"key":"2025010316451323100_bib35","first-page":"22","author":"American Society for Testing Materials","year":"2003"},{"key":"2025010316451323100_bib36","doi-asserted-by":"crossref","first-page":"126","DOI":"10.1080\/01926230490268756","article-title":"Best practices guideline: Toxicologic histopathology","volume":"32","author":"Crissman","year":"2004","journal-title":"Toxicol Pathol"},{"key":"2025010316451323100_bib37","volume-title":"Federal Insecticide, Fungicide and Rodenticide Act: Good Laboratory Practice Standards. 40 CFR Part 160","author":"Code of Federal Regulations","year":"2003"},{"key":"2025010316451323100_bib38","author":"Ministry of Health, Labour and Welfare","year":"1977"},{"key":"2025010316451323100_bib39","author":"Organization for Economic Co-operation and Development","year":"1997"},{"key":"2025010316451323100_bib40","doi-asserted-by":"crossref","first-page":"2031","DOI":"10.1007\/s00216-008-1973-4","article-title":"Development, standardization and refinement of procedures used for the evaluation of endocrine active compounds (EAC) on the development and sexual differentiation of Xenopus laevis","volume":"390","author":"Lutz","year":"2008","journal-title":"Anal Bioanal Chem"},{"key":"2025010316451323100_bib41","doi-asserted-by":"crossref","first-page":"691","DOI":"10.1289\/ehp.01109691","article-title":"Optimization of a yeast estrogen screen and its applicability to study the release of estrogenic isoflavones from a soygerm powder","volume":"109","author":"De Boever","year":"2001","journal-title":"Environ Health Perspect"},{"key":"2025010316451323100_bib42","doi-asserted-by":"crossref","first-page":"1456","DOI":"10.1002\/etc.5620210717","article-title":"An assessment of in vitro androgenic activity and the identification of environmental androgens in United Kingdom estuaries","volume":"21","author":"Thomas","year":"2002","journal-title":"Environ Toxicol Chem"},{"key":"2025010316451323100_bib43","volume-title":"Normal Table of Xenopus laevis (Daudin)","author":"Nieuwkoop","year":"1994"},{"key":"2025010316451323100_bib44","doi-asserted-by":"crossref","first-page":"290","DOI":"10.1177\/019262339101900313","article-title":"Peer review in toxicologic pathology: Some recommendations","volume":"19","author":"The Society of Toxicologic Pathologists","year":"1991","journal-title":"Toxicol Pathol"},{"key":"2025010316451323100_bib45","doi-asserted-by":"crossref","first-page":"655","DOI":"10.1177\/019262339702500624","article-title":"Documentation of pathology peer review","volume":"25","author":"The Society of Toxicologic Pathologists","year":"1997","journal-title":"Toxicol Pathol"},{"key":"2025010316451323100_bib46","volume-title":"Statistical Methods","author":"Snedecor","year":"1980","edition":"7th ed."},{"key":"2025010316451323100_bib47","volume-title":"Randomization, Bootstrap, and Monte Carlo Methods in Biology","author":"Manly","year":"1997","edition":"2nd ed."},{"key":"2025010316451323100_bib48","volume-title":"Statistics for Environmental Biology and Toxicology","author":"Piegorsch","year":"1997"},{"key":"2025010316451323100_bib49","doi-asserted-by":"crossref","DOI":"10.1002\/0471249688","volume-title":"Categorical Data Analysis","author":"Agresti","year":"2002","edition":"2nd ed."},{"key":"2025010316451323100_bib50","doi-asserted-by":"crossref","first-page":"339","DOI":"10.1242\/jcs.10.2.339","article-title":"Evolution of the nucleoli during oogenesis in Xenopus laevis studied by electron microscopy","volume":"10","author":"Van Gansen","year":"1972","journal-title":"J Cell Sci"},{"key":"2025010316451323100_bib51","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1007\/BF00357062","article-title":"Chromosome handling in amphibia","volume":"101","author":"Schmid","year":"1991","journal-title":"Chromosoma"},{"key":"2025010316451323100_bib52","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1080\/21564574.2005.9635519","article-title":"Assessment of laryngeal muscle and testicular cell types in Xenopus laevis (Anura pipidae) inhabiting maize and non-maize growing areas of South Africa","volume":"54","author":"Smith","year":"2005","journal-title":"Afr J Herpetol"},{"key":"2025010316451323100_bib53","doi-asserted-by":"crossref","first-page":"10","DOI":"10.1016\/j.aquatox.2009.07.018","article-title":"Population-specific incidence of testicular ovarian follicles in Xenopus laevis from South Africa: A potential issue in endocrine testing","volume":"95","author":"Du Preez","year":"2009","journal-title":"Aquat Toxicol"},{"key":"2025010316451323100_bib54","first-page":"281","article-title":"Determination of the sensitive stages for gonadal sex-reversal in Xenopus laevis tadpoles","volume":"34","author":"Villalpando","year":"1990","journal-title":"Int J Dev Biol"},{"key":"2025010316451323100_bib55","doi-asserted-by":"crossref","first-page":"41","DOI":"10.1002\/jmor.10162","article-title":"Pattern and rate of ovary differentiation with reference to somatic development in anuran amphibians","volume":"259","author":"Ogielska","year":"2004","journal-title":"J Morphol"}],"container-title":["Environmental Toxicology and Chemistry"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1002%2Fetc.133","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/academic.oup.com\/etc\/article-pdf\/29\/5\/1091\/59858401\/133.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/academic.oup.com\/etc\/article-pdf\/29\/5\/1091\/59858401\/133.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,1,3]],"date-time":"2025-01-03T16:45:47Z","timestamp":1735922747000},"score":1,"resource":{"primary":{"URL":"https:\/\/academic.oup.com\/etc\/article\/29\/5\/1091\/7763241"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2010,1,21]]},"references-count":55,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2010,1,21]]},"published-print":{"date-parts":[[2010,1,21]]}},"URL":"https:\/\/doi.org\/10.1002\/etc.133","relation":{},"ISSN":["0730-7268","1552-8618"],"issn-type":[{"value":"0730-7268","type":"print"},{"value":"1552-8618","type":"electronic"}],"subject":[],"published-other":{"date-parts":[[2010,5,1]]},"published":{"date-parts":[[2010,1,21]]},"assertion":[{"value":"2009-05-15","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2009-12-14","order":1,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2010-03-04","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}