|MadSci Network: Cell Biology|
First, I consulted with one of the world's experts on sperm, Prof. Kenneth Polakoski, to make sure the following is correct. Incidentally, Prof. Polakoski was the first scientist to isolate and name the enzyme ACROSIN, derived from the ACROsome (head) of the sperm. This enzyme is key to fertilization because it "dissolves" a tunnel through the outer membrane (called zona pellucida) of the egg, enabling the DNA from the sperm to get inside the egg. How long human sperm can live outside the human body depends on several things: temperature and humidity among them. At room temperature (75 °F or 25 °C) without dehydration the sperm can live between 4 and 6 hours. Dehydration means, without drying out. After all, the semen (viscous, whitish secretion of the male reproductive organs, containing spermatozoa and serving as their transporting medium) is over 85% water. So then if the semen loses water (dehydration) this material begins to crystallize; all the while the sperm cells also undergo water loss. Therefore, in ordinary dry air at room temperature when dehydration is an added factor, human sperm can live maybe 1 to 3 hours. That's about all.
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