The nucleus of the fertilized egg can be removed and a nucleus from white cells of a mother or father can be inserted and if development continues then we have an offspring which is a zerox copy of mother or father. We have to know how to turn these genes on and off. By introducing the gene at the two celled stage we can expect the desired result. In other words we have to manipulate embryos in virto. It is possible to collect embryos from females, culture them in virto, freeze and store them indefmitely in liquid nitrogen. We can later bring them back to activity, sex them and transfer them back to the reproductive tract of recipient to obtain normal offspring.
Individual embroys can be divided into two resulting in identical twins or 3 or 4 parts making them triplets and quadruplets. These techniques can be used to increase the female reproductive rate analogue to artificial insemination used in males in animals. Production of bull calves by embryo transfer is an efficient means of amplifying genes of the best cows through their sons.[38]