Rihachi Iizuka has contributed strong leadership for the remarkable development of reproductive medicine which has undergone a complete transformation in the previous half century. The Keio University Hospital introduced artificial insemination as the first assisted reproductive technology in Japan. As it follows, Iizuka and his colleagues first reported the live birth of a female infant in August 1949 after heterologous insemination: AID. Iizuka and his colleagues were also among the first to successfully inseminate a woman with sperm that had been frozen. He developed the new cryopreservation medium for human semen called "KS Cryo-medium". He also developed semen preparation methods of washing and concentrating sperm counts by centrifugation with Percoll (colloidal silica derivative) solution for oligozoospermic patients. These methods are broadly used in the clinical field. Furthermore, he developed the X-, Y-bearing sperm preseparation method using Percoll which is the so-called "gender selection" procedure for preventing X-linked genetic disorders. The most striking assisted reproductive technology was in vitro fertilization first carried out in Britain. Prior to the clinical application in Japan, the Japan Society of Fertilization and Implantation was established as the main organ for the exchange of official scientific information by lizuka in 1982. As rapid development and spreading of in vitro fertilization and its implicated technologies, lizuka and his colleague of the department had the first success of offspring following embryo freezing and thawing in Japan which was performed at the Tokyo Dental College Ichikawa General Hospital. Already the numbers of offspring following in vitro fertilization treatment has risen to approximately 1% of births in Japan. Rihachi lizuka still undertakes the responsibility for reproductive medicine as he has done so far.
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