| Budget Amount *help |
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1986: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1985: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Research Abstract |
In order to address the question about the regulatory mechanism in spermatogenesis, I have been trying to make culture systems which support spermatogenesis in vitro. So far , I have established a culture of spermatogenic cells from Japanese newt, Cynops pyrrhogaster : Dissociated primary spermatocytes completed first and second meiotic divisions, resulting in round spermatids which formed flagella, acrosomes, rings and neckpieces. Dissociated spermatids elongated their nuclei.
However, in order to understand how such various shape of mature sperm is formed, it is desirable to make several culture systems from several species. Hopefully they should be cultured in the same medium at the same temperature. So, we tried to culture primary spermatocytes from Xenopus laevis. The primary spermatocytes completed first and second meiotic divisions and produced quadruplets of round spermatids within a day. The spermatids formed flagella and acrosomes; later the acrosomes condensed. Finally, the s
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permatids elongated and the round nuclei were situated on one side of the cells. However, nuclear elongation did not occur. Electron microscopic observation revealed that round mitochondria assembled around the nuclei of spermatids when the acrosomes were formed. A flagellum was formed during interphase of secondary spermatocytes. The efficiency of differentiation to the stage of the formation of flagella and acrosomes in spermatids was greater than 90%. The possible contribution of Sertoli cells to the promotion of differentiation was excluded by removing the Sertoli cells from the cultures. The time schedule of differentiation in vitro was obtained at 22 c.
Comparing the two culture systems from newt and Xenopus, several different aspects in spermatogenesis were clarified in vitro, such as the length of flagella, size of acrosomes , and assembly of mitochondria. Future studies on the differences between newt and Xenopus spermatogenesis in vitro at the cellular and molecular levels should provide insight into the regulatory mechanisms in spermatogenesis. Less
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