ABSTRACT
The objective of prolonged storage of tissues that could be revitalized following suspended animation in cryostorage was envisioned by Dr John Hunter over two centuries ago. Since then significant advances have been made in cryopreservation of living cells, especially in the 1940s when it was discovered that glycerol greatly enhanced survival of cryopreserved living cells.1 Around that time investigations by Chang on low temperature storage of rabbit oocytes, zygotes, and embryos2,3 paved the way for studies on cryopreservation of female gametes and embryos. Subsequent experiments in the 1950s by Lin and Sherman4-6
demonstrated that mouse oocytes could also be cooled in glycerol, stored, and, subsequently, fertilized in recipients, resulting in embryos that support pregnancies. In the 1960s early investigations by Mazur7,8 formed the foundation for understanding cellspecific optimal cooling and warming rates which today remain as pivotal keys to successful mammalian gamete and embryo cryopreservation. Then in the 1970s the combined strengths of Mazur, Leibo, and Whittingham resulted in successful cryopreservation of mouse embryos.9 In 1977 the first successful IVF with live offspring from cryopreserved mouse oocytes was reported,10
followed by the first human pregnancies after embryo cryopreservation.11,12 Finally in 1986, Chen reported the first pregnancy after human oocyte cryopreservation.13
