| Budget Amount *help |
¥16,250,000 (Direct Cost: ¥12,500,000、Indirect Cost: ¥3,750,000)
Fiscal Year 2019: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2018: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2017: ¥7,800,000 (Direct Cost: ¥6,000,000、Indirect Cost: ¥1,800,000)
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| Outline of Final Research Achievements |
During passage through the female reproductive tract, the spermatozoa massively decrease in number, and only a small number of sperm are able to reach the site of fertilization. However, the exact mechanism of sperm selection is poorly understood. Here, we investigated sperm entry into the sperm storage tubules (SSTs) and subsequent fertilization success under a competitive situation created by artificial insemination of a sperm mixture obtained from two males. We found paternity of embryos was biased towards males with longer flagellum when a sperm from the two males strains was artificially inseminated into females. Our novel sperm staining method with two different fluorescent dyes showed that the biased fertilization was due to the better ability of the sperm to enter the SSTs. Our results indicated that sperm competition occurs to win a place in the SSTs, and that filling the SSTs with their own spermatozoa is a critical step to achieve better fertilization success.
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