Origins of techniques in human and animal embryology.

Increasingly innovative and imaginative techniques are being developed to investigate the development of animal and human embryos. Among the types of techniques that have been developed are ones that deal with oocyte maturation and culture, the isolation and utilization of stem cells, cryopreservation of reproductive cells and tissues, and various procedures to manipulate early embryos. To appreciate the derivation of these sophisticated techniques, it seems appropriate to consider the very early origins of these current techniques.