Cleavage is dividing. When the injected egg divides in two, we know that fertilization was successful and the embryo, now called a zygote, or early embryo is growing. This followed by successive divisions resulting in 4,8,16 etc cells inside the embryo. We now have the option of transferring the cleaved egg into the oviduct of a recipient mare surgically, or trying to grow it into a morula (5 to 6 day embryo) and transfer it thru the cervix as we do embryo transfer. Recent advances in our culture system have resulted in the majority of our cleaved oocytes reaching blastocyst stage in the incubator. This series shows the same oocyte becoming a blastocyst.