Generally chopping up the testes released the milt that contains the sperm, but leaves a lot of chunks to deal with later. Getting the milt/sperm out by putting the testes in a garlic press works slick as a whistle with nothing but fluid on the other end. Like the eggs, the milt must also be expressed into a dry container. Any water will activate the sperm which only live about a minute. If they haven't found an egg in this time, it is too late.