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This Article Full Text Full Text (PDF) All Versions of this Article: 68/1/328    most recent biolreprod.102.003749v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Tanaka, Y. Articles by Taya, K. Search for Related Content PubMed PubMed Citation Articles by Tanaka, Y. Articles by Taya, K. Agricola Articles by Tanaka, Y. Articles by Taya, K.

Localization and Secretion of Inhibins in the Equine Fetal Ovaries¹

^a Department of Basic Veterinary Science, The United Graduate School of Veterinary Science, Gifu University, Gifu 501-1193, Japan ^b Laboratory of Veterinary Physiology, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan ^c Department of Veterinary Pathology, Rakuno Gakuen University, Hokkaido 069-8501, Japan ^d Shadai Corporation, Hokkaido 059-1432, Japan ^e Equine Research Institute, Japan Racing Association, Tochigi 320-0856, Japan ^f Laboratory of Racing Chemistry, Tochigi 320-0851, Japan ^g School of Biological and Molecular Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom

To clarify the source of inhibins in equine female fetuses, concentrations of immunoreactive (ir-) inhibin, inhibin pro-C, and inhibin A in both fetal and maternal circulation and in fetal ovaries were measured. In addition, the localization of inhibin and inhibin/activin ß_A, and ß_B subunits and the expression of inhibin _A and inhibin/activin ß_A subunit mRNA in fetal ovaries were investigated using immunohistochemistry and in situ hybridization. Concentrations of circulating ir-inhibin, inhibin pro-C, and inhibin A were remarkably more elevated in the fetal than in the maternal circulation between Days 100 and 250 of gestation. Fetal ovaries contained large amounts of ir-inhibin, inhibin pro-C, and inhibin A. In contrast, these inhibin forms were undetectable in both the maternal ovaries and placenta. The inhibin and inhibin/activin ß_A and ß_B subunit proteins were localized to enlarged interstitial cells of the equine fetal ovary. Expression of inhibin and inhibin/activin ß_A subunit mRNAs were also observed in the interstitial cells. We conclude that the main source of large amounts of inhibins in fetal circulation is interstitial cells of fetal ovary and is not of maternal origin. Furthermore, these inhibins may play some important physiological roles in the development of gonads in the equine fetus.

¹ This work was supported by a grant-in-aid from the Equine Research Institute of the Japan Racing Association.

² Correspondence: Kazuyoshi Taya, Laboratory of Veterinary Physiology, Tokyo University of Agriculture and Technology, 3–5–8, Saiwai-cho, Fuchu, Tokyo 183-8509, Japan. FAX: 81 42 367 5767; taya{at}cc.tuat.ac.jp