| Project/Area Number |
06640858
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
生物形態・構造
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| Research Institution | University of Tsukuba |
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Principal Investigator |
HORI Terumitsu Institute of Biological Sciences University of Tsukuba Professor, 生物科学系, 教授 (90057563)
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| Co-Investigator(Kenkyū-buntansha) |
MIYAMURA Shin-ichi Institute of Biological Sciences University of Tsukuba Assistant Professor, 生物科学系, 講師 (00192766)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1995: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1994: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Cycas / Ginkgo / male nucleus receptor apparatus / gymnosperm / sexual reproduction / fertilization / Cyeas vevoluta |
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| Research Abstract |
In this study the developmetnt and differentiation of the male nucleus receptor apparatus were investigated in two gymnosperms, Cycas revoluta and Ginkgo biloba. The apparatus functions as a specialized receptor for the acceptance of the male nucleus and as a site of fusion of the gametangial nuclei during fertilization. It is a depression of the nuclear envelope which is frilled with many fine fuzzy foldings of the nuclear membrane. In the egg nucleus of Cycas the apparatus firstly differentiate at its lateral side with regard to the direction of nuclear migrrtion towards the cell center. Finally it locates at the anterior region of egg nucleus facing the neck cells of the archegonium. After fusion of the sperm and egg cells the male nucleus migrates towards the female nucleus in the egg cytoplasm and is accomodated into depression of the female nucleus. The apparatus of G.biloba differentiates during the migration of male nucleus toward the female nucleus after fusion of both reproductive cells. The difference of behavior of the apparatus in these two plants is probably effected by different sizes of egg cells ; the female nucleus of Cycas is tremendously large, measuring more than 2 mm logn and 1-1.5 mm wide, while it measures approximately 350 mum in diameter. Therefore, distance of the nuclear migration in the egg cytoplasm is conspicuously long in the former and shot in the latter. According to comparison of cell size of egg cells and fusion manner of gametangial nuclei formation of the identical structure is expected in plants of the family Pineaceae.
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