In hamsters, high potassium levels in the oviduct don't stop the process of sperm fertilizing an egg, even though they hinder the usual membrane changes in the sperm's tail. The study confirmed that hamster sperm, like other mammals, go through a specific change in their membrane when they are ready for fertilization. When the researchers raised the potassium levels in the lab setting, the sperm's tail did not change as expected, but the sperm could still move, swim vigorously, and release certain substances needed for fertilizing the egg. This surprising result questions the actual importance of this specific membrane change in the fertilization process of hamsters.