“Revival of Spermatozoa after Dehydration and Vitrification at Low Temperatures” (1949), by Christopher Polge, Audrey Ursula Smith, and Alan Sterling Parkes
In the 1949 article “Rev
“Revival of Spermatozoa after Dehydration and Vitrification at Low Temperatures” (1949), by Christopher Polge, Audrey Ursula Smith, and Alan Sterling Parkes
In the 1949 article “Revival of Spermatozoa after Dehydration and Vitrification at Low Temperatures,” researchers Christopher Polge, Audrey Ursula Smith, and Alan Sterling Parkes demonstrated that glycerol prevents cells from dying while being frozen. Polge and his colleagues discussed several procedures in which they had treated sperm cells from various species with glycerol, froze those cells, and then observed the physiological effects that freezing had on the treated sperm. The researchers concluded that glycerol safely preserves sperm samples from a variety of species. Polge, Smith, and Parkes’s 1949 article detailed one of the first successful uses of a chemical medium to preserve viable cells in a frozen state, a process that eventually enabled the first vertebrate embryo to be successfully conceived using frozen sperm.
A team of three authors wrote the article “Revival of Spermatozoa after Dehydration and Vitrification at Low Temperatures.” In the late 1940s, Polge and Smith collaborated with their supervisor, Parkes, to research the effects of freezing conditions on sperm samples from a variety of species. All three scientists worked at the National Institute for Medical Research in London, England, an organization funded by the British government’s Medical Research Council, also based out of London.
Throughout the 1940s, researchers worked to determine a process for safely freezing cells that would be viable for use after thawing. Freezing a sperm sample enables that sperm to fertilize an embryo at a specific time after it was initially produced by a male, but freezing can have lethal or disabling effects for the cell. Under natural conditions, exposing cells to freezing temperatures results in total cell death. Formation of ice crystals within and around the cell ruptures the membrane of the cell, resulting in cell death. High salt concentrations within the cell that result from water leaving the cell can also irreparably damage cellular components. By 1949, no frozen sperm cell of any species had successfully fertilized an egg and resulted in a viable embryo.
In “Revival of Spermatozoa,” Polge, Smith, and Parkes report how they tested multiple freezing protocols on samples of poultry sperm in an effort to produce thawed sperm cells that could ultimately yield viable embryos through fertilization. Although the authors did not divide the one-page article into sections, there are four themes or sections that exist within the article. In the first section, the authors introduce prior experiments in which researchers had frozen and studied sperm cells. In the next section Polge, Smith, and Parkes detail their own experiments, in which they observed the effects that mixing glycerol and similar compounds with human sperm, rabbit sperm, and fowl sperm have on the functionality of the different sperm types after being frozen and thawed. In the third section, the authors discuss results when applying similar techniques to freeze dried sperm samples. In the fourth section, the authors summarize the implications of their research and allude to further research.
In the first section, Polge, Smith and Parkes summarize earlier research that involved the freezing of sperm cells through a process called vitrification. Vitrification is the process by which materials, such as cells, are frozen in a manner that prevents the formation of ice crystals. The authors note that human sperm is resistant to the vitrification process, but they do not explain that claim. They also state that when human sperm samples are frozen in 