He made numerous key contributions to the study of mammalian fertilization, and he was also a pioneer in the cloning field.

Being unable to find a research position initially, he then worked as a high school teacher for two years.

[2] Yanagimachi applied for a post-doctoral position with Dr. M. C. Chang of the Worcester Foundation for Biomedical Research in Shrewsbury, Massachusetts.

[3][4] In July 1998, Yanagimachi's team published work in Nature on cloning mice from adult cells.

This was accomplished by an international team of scientists, including co-authors Teruhiko Wakayama, Tony Perry, Maurizio Zuccotti and K.R.

[5][6] The Yanagimachi laboratory moved from the warehouse which had housed it for over thirty years into the newly created Institute for Biogenesis Research in the Biomedical Sciences Tower of the John A. Burns School of Medicine.

As a graduate student of Hokkaido University in Japan, Yanagimachi studied fish (herring) fertilization and the sexual organization of rhizocephalans (parasitic barnacles).

In fish, he discovered calcium-dependent, chemotactic movement of spermatozoa into the micropyle through which the fertilizing spermatozoon enters the egg.

His comprehensive review of the basic biology of "Mammalian Fertilization" published in 1994 (In: Physiology of Reproduction, Knobil & Neill eds, Ravan Press) is classic.