Deformed sperm cell. Coloured scanning electron micrograph (SEM) of an abnormal sperm cell, or spermatozoon, due to residual cytoplasm (lump, centre). This is an immature characteristic in sperm cells, and makes them unable to fertilise an egg cell (ovum). All men have a few deformed sperm in their ejaculate, but an overabundance of them can mean that the man is infertile. Magnification: x2100 when printed 10 centimetres tall.