Journal of Reproduction and Development
Online ISSN : 1348-4400
Print ISSN : 0916-8818
ISSN-L : 0916-8818
Original Article
Relationship between Serum Sex Hormone Concentrations and Histology of Seminiferous Tubules of Captured Baleen Whales in the Western North Pacific during the Feeding Season
Hiroyuki WATANABEToshihiro MOGOEMasatsugu ASADAKengo HAYASHIYoshihiro FUJISEHajime ISHIKAWASeiji OHSUMIAkio MIYAMOTOYutaka FUKUI
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2004 Volume 50 Issue 4 Pages 419-427

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Abstract

The present study was conducted to obtain new information on relationships among serum testosterone (T), estradiol-17 β (E2), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) concentrations and histology of seminiferous tubules in captured common minke and Bryde’s whales during the feeding season. Blood samples and testes were collected from common minke (n=39 for blood samples, n=15 for testes) and Bryde’s (n=14 for blood samples, n=7 for testes) whales captured from May 2001 to August 2001 in the Western North Pacific. Serum T concentrations, in 35.9% of the common minke and 57.1% of Bryde’s whales, were below the detection limit (< 2.5 pg/ml). There were no significant differences in the serum concentrations of E2, FSH, and LH among immature, mature common minke and Bryde’s whales except that LH levels of immature Bryde’s whales was higher than those of common minke whales. In most seminiferous tubules of mature whales, only a single-layer of spermatogonia was observed. However, spermatozoa were observed in seminiferous tubules in 2/13 of mature common minke and 4/4 of mature Bryde’s whales with the low or undetectable T levels. These results indicate that the low serum T concentrations reflect the inactivity of spermatogenesis in both baleen whales, and that it is not possible to assess gonadal activity in either common minke or Bryde’s whales using serum sex hormone concentrations during the feeding season.

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この記事はクリエイティブ・コモンズ [表示 - 非営利 - 改変禁止 4.0 国際]ライセンスの下に提供されています。
https://creativecommons.org/licenses/by-nc-nd/4.0/deed.ja
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