EARLY WORK ON FREEZING SEMEN

While it has been known for a long time that various types of tissues and organisms can withstand freezing and are even preserved by freezing, the first attempts at freezing sperm cells were made before the turn of the century. In 1897, Davenport[1] [B] found that human sperm would withstand freezing. For thirty to forty years after that, little attention was paid to freezing as a possible means of preserving semen. An excellent review of the early attempts to freeze sperm has been assembled by Polge and Parkes.[2] These investigators also gave a good account of their work at the British National Institute of Medical Research in London, where in 1949 they demonstrated that glycerol would protect fowl sperm so that it would survive freezing. The next year they found that bull sperm and the sperm of several other species were protected by glycerol during freezing. During the same year, Emmens and Blackshaw[3] showed that ram and bull sperm would survive freezing. In 1951 frozen semen was used to produce a calf in England and a lamb in Australia.

The highlights in the development of frozen semen have been covered by other reviews and reports. Interested persons will find the articles of Polge and Parkes[2] and Smith[4] especially good on the early history and theoretical aspects of freezing sperm. Later progress on the freezing procedure has been reviewed and covered in a number of detailed reports.[5], [6], [7] Many items not covered in those articles have been assembled here.