Further optimization of mouse spermatozoa evaporative drying techniques

It has been shown in the past that mouse spermatozoa could be dried under a stream of nitrogen gas at ambient temperature and stored at 4 degrees C or 22 degrees C for up to 3 months and was capable of generating live-born offspring. In previous desiccation work, dried sperm were stored in a vacuum-sealed plastic bag placed in a vacuum-packed Mylar bag. However, dried specimens stored in this way often lost moisture, particularly in samples stored at higher temperatures (22 degrees C) compared to lower temperatures (4 degrees C). The present report describes a method which minimizes this water loss from the dried sperm samples. Its use is described in a preliminary study on the effect of supplementing the trehalose with glycerol. The results have demonstrated that mouse sperm can be stored at 4 degrees C over saturated NaBr without the uptake of water which occurs when they are stored in Mylar packages. In addition, we were able to get some survival of sperm (9-15%) at room temperature storage after 3 months. The addition of glycerol to trehalose had little effect on the survival of dried mouse sperm stored over NaBr for 1 and 3 months.