The reproductive status of Steller sea lions in the Nemuro Strait, Hokkaido, Japan

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概要

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• The reproductive tracts of 29 female Steller sea lions Eumetopias jubatus collected in the Nemuro Strait, Hokkaido, Japan, during the winters of 1995 and 1996, were examined to estimate their reproductive histories and status. After sectioning ovaries at intervale of 250μm thickness, a light microscope was used to examine 23 of the 57 ovaries for small retrograde corpora lutea (RCLs). None of the RCLs that were more than three years old were found. The regression process of an RCL is presumed to occur rapidly because of the pressure exerted by a large corpus luteum of pregnancy (PCL) formed during the subsequent pregnancy. No more than three placental scars were found in any one female, probably because the scars disappeared during placentation during subsequent pregnancies. Thus, estimations of the reproductive histories of Steller sea lions were not possible beyond three years. Females became sexually mature from four to seven years of age, which was one year later than in previous studies (Perlov 1971). Among those sampled during January and February, the pregnancy rate for females that had ovulated was 88.5% (23/26).

• 野生生物保護学会の論文

著者

• Endo Tsuyoshi

  Laboratory Of Veterinary Physiology College Of Bioresource Sciences Nihon University

• Ishinazaka Tsuyoshi

  Laboratory of Veterinary Physiology, College of Bioresource Sciences, Nihon University

• Ishinazaka Tsuyoshi

  Laboratory Of Veterinary Physiology College Of Bioresource Sciences Nihon University:(present Addres

• Ishinazaka Tsuyoshi

  Laboratory Of Wildlife Biology Department Of Environmental Veterinary Sciences Graduate School Of Ve

• Ishinazaka Tsuyoshi

  Laboratory Of Theriogenology College Of Bioresource Sciences Nihon University

• Ishinazaka Tsuyoshi

  Department Of Veterinary Medicine College Of Bioresource Sciences Nihon University

• Ishinazaka Tsuyoshi

  Laboratory Of Wildlife Biology Graduate School Of Veterinary Medicine Hokkaido University

関連論文

• The reproductive status of Steller sea lions in the Nemuro Strait, Hokkaido, Japan
• Optimum Dose of LH-RH Analogue Fertirelin Acetate for the Induction of Superovulation in Mice
• Distribution of the Steller sea lion Eumetopias jubatus during winter in the northern Sea of Japan, along the west coast of Hokkaido, based on aerial and land sighting surveys
• Sex Determination of Sika Deer (Cervus nippon yesoensis) Using Nested PCR from Feces Collected in the Field
• Distribution and abundance of spotted seals Phoca largha and ribbon seals Phoca fasciata in the southern Sea of Okhotsk
• The physiology and life-history parameters of reproduction in Steller sea lions, spotted seals and ribbon seals from the coastal waters of Hokkaido
• Immunohistochemical Localization of Steroidogenic Enzymes and Prolactin Receptors in the Corpus Luteum and Placenta of Spotted Seals(Phoca largha) during Late Pregnancy.

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