1997 Fiscal Year Final Research Report Summary
Hormonal Regulation of Follicular Transformation to the Rapid Growth Phase in Hen's Ovary
| Project/Area Number |
07660384
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied animal science
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| Research Institution | Nihon University |
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Principal Investigator |
IMAI Kiyoshi Nihon University, College of Bioresource Sciences, Professor, 生物資源科学部, 教授 (90023423)
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| Co-Investigator(Kenkyū-buntansha) |
KAI Osamu Nihon University, College of Bioresource Sciences, Associate Professor, 生物資源科学部, 助教授 (90115543)
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| Project Period (FY) |
1995 – 1997
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| Keywords | time of follicular transformation / criteria for follicular transformation / inhibition of follicular transformation / estrogen producing capacity / estrogen receptor / aminoglutethimide / tamoxifen / タモキシフェン |
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| Research Abstract |
The present research was conducted to investigate endocrine regulatory mechanisms relating to the follicular transformation to the rapid growth phase in hen's ovary.
The results obtained were as follows ;
1.The situation of yolk sphere layrs formed in small folliciles was sdeful to judge the follicular transformation as well as the existence of the fat soluble dye in small follicles. Using the criteria stated above, it was confirmed that follicular transform ation occurred at a high frequency within the period from 8 to 11 hr after C_s ovipositi on in laying hens.
2.When aminoglutethimide (AG), a steroidogenesis inhibitor, was injected to hens 2 hr after C_s oviposition, follicular transformation was blocked in half the hens. Plasma estradiol-17 beta (E_2) from AG treated hens with follicular transformaton was higher than those without transformation. In contrast, follicular transformation occurred at the same frequency in hens injected with AG or vehicle 2 hr before the predicted C_s oviposi tion time.
When theca layr of small follicles collected at various times after C_s oviposition was individually incubated, one of the follicles revealed high E_2 producing capacity during several hours before the transformation. Although E_2 producing capacity of the follicles decreased by AG treated 2 hr after C_s oviposition, a relatively high capacity was still remained in only one small follicle comparing with others.
4.Estrogen receptor (ER) positive cells were localized in the theca externa of small follicles in hen's ovary. No difference was found, however, on ER immunoreactivity during the period before follicular transformation. On the other hand, administration of tamoxifen, an antiestrogen, to laying hens caused the failure of follicular transformation and the increase of ER immunoreactivity.
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