High cholesterol content and decreased membrane fluidity in human spermatozoa are associated with protein tyrosine phosphorylation and functional deficiencies.

Too much cholesterol in sperm makes it harder for them to get ready to fertilize an egg, because it stops key changes they normally need to make.

Sperm cells with too much cholesterol and a similar fat called desmosterol don't move as well when they're getting ready to fertilize an egg, and this might be because those fats mess with their internal signaling system.

Cholesterol makes up about half of the fatty material in the outer layer of your body's cells, and it helps keep that layer flexible, strong, and able to control what comes in and out.

Sperm that don't swim well have much more cholesterol and a related molecule called desmosterol than good swimmers, and they can't make their outer membrane more flexible when they're getting ready to fertilize an egg — this seems to be linked to weaker chemical signals and less powerful movement.

Too much cholesterol in sperm cells stops them from becoming more flexible when they need to, which stops them from activating the internal signals needed to swim powerfully toward an egg.

Sperm that don't swim well have stiffer outer membranes than sperm that swim well, and this stiffness doesn't go away even when the sperm are supposed to become ready for fertilization.