Ryuzo Yanagimachi

In 2014, he had an interview with The Prism in which he was quoted saying:

Yanagimachi himself considered "cloned mice" to be byproducts of fertilization study and that the production of cloned animals in various species triggered/accelerated the research on the genomic reprogramming of adult somatic (body) cell nuclei as well as the production of pluripotent stem cells from adult cells for therapeutic purposes. He retired in 2005, but continues working on natural and assisted reproduction.

The Yanagimachi laboratory and his former associates continued to make advances in cloning. The first male animal cloned from adult cells was announced in 1999. In 2004 the laboratory participated in the cloning of an infertile male mouse. This advance may be used to produce many infertile animals for use in research in human infertility.

In July 1998, Yanagimachi's team published work in Nature on cloning mice from adult cells. Yanagimachi named the new cloning technique they had created to do this work the "Honolulu technique". The first mouse born was named Cumulina, after the cumulus cells whose nuclei were used to clone her. At the time of the publication of this work, over fifty mice spanning three generations had been produced through this technique. This was accomplished by an international team of scientists, including co-authors Teruhiko Wakayama, Tony Perry, Maurizio Zuccotti and K.R. Johnson.

Throughout his career he has made numerous, fundamental contributions to our understanding of mammalian fertilization and to the development of assisted fertilization technologies such as in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) which are widely used today in human infertility clinics throughout the world. His comprehensive review of the basic biology of "Mammalian Fertilization" published in 1994 (In: Physiology of Reproduction, Knobil & Neill eds, Ravan Press) is classic.

In 1966 Yanagimachi ended up at the University of Hawaii as an assistant professor and has become a full professor of the department of anatomy and reproductive biology at the John A. Burns School of Medicine. After working for 38 years at the University of Hawaii, he retired in the end of 2005 to become a professor emeritus, but keeps working with junior fellows. He is married to Hiroko, a former child psychologist. She could not find work in her field when they came to the U.S. due to a language barrier, so she went to work with researchers in his lab as an electron microscopist.

In 1964, he returned to Hokkaido University as a temporary lecturer, with the possibility of later being appointed to an assistant professorship. However, another person eventually got the position.

While he was at the Worcester Foundation for Biomedical Research as a Dr. M.C. Chang's postdoctoral fellow (1960-1964), he witnessed and recorded the entire process of sperm penetration through the zona pellucida and fusion with the egg proper in a living (hamster) egg, which was the first in mammals. He was one of few who began to study the process and mechanisms of mammalian fertilization using in vitro fertilization technique.

Yanagimachi was born in Ebetsu and raised in Sapporo, Japan. He received a BS in zoology in 1952 and a DSc in animal embryology in 1960 both from Hokkaido University. Being unable to find a research position initially, he then worked as a high school teacher for two years.

Ryuzo Yanagimachi (柳町 隆造, Yanagimachi Ryūzō, born August 27, 1928) is a Japanese-born, American-based scientist. He has made numerous key contributions to the study of mammalian fertilization. He is a pioneer of assisted fertilization technologies such as in vitro fertilization and direct sperm injection into the egg (commonly called intracytoplasmic sperm injection or ICSI), which are widely used today in human infertility clinics throughout the world. He was also a pioneer in the cloning field. In 1997, his laboratory at the University of Hawaii at Manoa successfully cloned mice using the Honolulu technique.