[Strain maintenance and freeze preservation of embryos]

In the low temperature preservation of mammalian embryos, embryos obtained by in vivo or in vitro fertilization of the female are preserved at extremely low temperatures (-196 degrees C: LN2). When required, they are thawed and development is continued. This technique is one type of research started in recent years to save on labor involved in strain maintenance and to preserve strains in the genetic and breeding fields. In this paper, an outline of low temperature preservation and its utilization with small experimental animals is given.