Transgenic animals are when one animal carries a different gene from another animal. This procedure has only really been done on mice and the first successful one was done on a mouse. There are three ways of producing transgenic animals, one is called DNA microinjection. This is when you transfer of a desired gene construct from a member of the same species or from a different species into the pronucleus of a reproductive cell. Then, you take the manipulated cell and transfer it to the recipient female after it is cultured in vitro. The second way is called Retrovirus-Mediated Gene transfer which is when retrovirus used as vectors to transfer genetic material into the host cell resulting in a chimera, then the chimeras are inbred for as many as 20 generations until homozygous. The final method is called Embryonic Stem Cell-Mediated Gene Transfer, this is when you isolate stem cells form embryos and the desired genes are inserted into these cells and then the cells that contain the desired DNA are incorporated into the host embryo. Some advancements are agriculturally, medical and industrial. Agriculturally, transgenic cows are made that produce more milk and milk with less lactose and cholesterol. Pigs that have more meat with them and sheep’s that grow more wool. Medically, products such as insulin, growth hormones and blood anti-clotting factors may soon be or are obtained from cows, sheep’s or goats. Industrially, two scientists at Nexia Biotechnologies in Canada spliced spider’s genes in cells of goats. The goats started producing milk along with silk strands. Those silk stands where used for creating light, tough, flexible materials in military uniforms, tennis rackets etc. Transgenic animals have changed the world by having the ability to have genes from one animal to another animal to in the case of cows produce more milk and in other cases helping advances medical studies and sciences and in many other different fields of study.