@inproceedings{oai:jaxa.repo.nii.ac.jp:00013819,
 author = {渡辺, 明彦 and 今井, 真理子 and 高山渡辺, 絵理子 and 鬼武, 一夫 and Watanabe, Akihiko and Imai, Mariko and TakayamaWatanabe, Eriko and Onitake, Kazuo},
 book = {宇宙利用シンポジウム　第20回　平成15年度, Space Utilization Research: Proceedings of the Twentieth Space Utilization Symposium},
 month = {Mar},
 note = {Spermiogenesis is the final step of spermatogenesis that takes place in a differentiating spermatid. Some events orderly progress in the spermatid as a result of having contact with Sertoli cells in the testis of vertebrates. Each event in spermiogenesis is controlled by the combined effect of an intrinsic control of the spermatid and the germ-somatic cell interaction in vertebrates. A culture system of spermatogenic cells has been established in the medaka fish, Oryzias latipes. In the culture, primary spermatocytes differentiate into fertilizable sperm, through meiosis and spermiogenesis. These processes proceed without contacting Sertoli cells. On the other hand, the timing of these events in the cultured spermatids, agree with that in vivo, suggesting that it is intrinsically controlled in the cultured spermatids. This control mechanism is suggested to be similar to that acts in vivo. It has been demonstrated that this culture system is available to estimate the influences of hypergravity in the mechanism controlling spermiogenesis in vertebrates. In the present study, the cell culture of primary spermatocytes of the medaka fish was centrifuged at 10 G and the influences of hypergravity were estimated in the spermiogenic events, especially in the cytoplasmic lobe formation. When the primary spermatocytes were cultured at 10 G, the timing for meiotic division completion agreed with that observed in the culture at 1 G, as the control. The cytoplasmic lobe formation was suggested to take place in the spermatids after completing the organelle replacement, thus the shapes of the cultured spermatids were observed using scanning electron microscopy. In Day 4, protrusions were observed in many spermatids and the elongated protrusions were typically observed in the spermatids in Day 5. Using transmission electron microscopy, the protrusion was sited near the flagellum and many organelles, such as mitochondria and vacuoles, were observed in its cytoplasm. Thus, the protrusion corresponded to the cytoplasmic lobe. In Day 4, four types of spermatids were observed: the spermatids with a large round head (stage 1), with small protrusions (stage 2), with elongated protrusions (stage 3) and with a small round head (stage 4). Every type of spermatid was also observed in the culture at 10 G. However, the percentages of spermatids at stage 1 and at stage 2 were larger than those in the control. This result suggests that hypergravity suppressed the cytoplasmic lobe formation in the cultured spermatids. This cell culture system can be used for estimating the influences of gamete production in vertebrates against a specialized environment in space., 資料番号: AA0046917014},
 pages = {39--40},
 publisher = {宇宙航空研究開発機構宇宙科学研究本部, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA/ISAS)},
 title = {加重力環境が細胞培養下の精子完成における細胞質小葉形成に及ぼす影響に関する研究},
 year = {2004}
}