51.   The phenomenal feat of the male fruit fly is believed to have evolved in order to prevent females having their eggs fertilized by other males.

52.   The sperm would fertilize the egg while the cytoplasm, they hoped, would allow the embryo to develop.

53.   Then the scientists tried to use those sperm to fertilize eggs, asking whether the added jellyfish genes became part of the developing embryos.

54.   Their litters are smaller than normal and gestation takes a couple of days longer, indicating that it is taking the sperm a longer time to fertilize the eggs.

55.   Then the egg can be fertilized.

56.   They had insisted that the children should be recognized as British citizens because one of their sperm fertilized the egg of a donor that was planted in the surrogate.

57.   Three out of eight eggs were fertilized.

58.   To produce a female, she fertilizes the egg with her cache of sperm before laying it.

59.   Typically, an embryo reaches the four-cell stage roughly two days after the egg is fertilized.

60.   When one sperm manages to fertilize the egg, the first divisions of the embryo take place.