case of oct 4 for example mouse antibodies which are known to be reactive to human oct 4 are exposed to ruminant embryos in the expectation that the mouse antibodies are cross reactive to ruminant oct 4 accordingly antibody complexes form when the pluripotency factor is present in the embryo in a preferred embodiment of the present invention human antibodies which are known to be reactive to human pluripotency factors are used in the same way as the mouse antibodies described above the antibody complex is then detected for example the antibody complex may be detected by washing staining and mounting the embryos on slides replication and amplification of the relevant nucleotides is conducted as understood in the art with respect to rt pcr and sequencing analysis rna is extracted from embryos at various stages in one embodiment specific primers for oct 4 nanog sox2 fgf4 and fgfr2 are used sox2 primers were designed based on homology between human and mouse sox2 open reading frame the sense primer used is 5 u2032 aagatgcacmctcggagatca 3 u2032 seq id no 9 the antisense primer used is 5 u2032 agccgttcatgtaggtctgcg a 3 u2032 seq id no 10 the invention covers fgf4 primers for example the sense primer 5 u2032 ttcttcgtggccatgagcag 3 u2032 seq id no 11 and the antisense primer 5 u2032 aggmgtgggtgaccttcat 3 u2032 seq id no 12 the invention also covers fgfr2 primers such as the sense primer 5 u2032 gtcatcgttgaatacgcctc 3 u2032 seq id no 13 and the antisense primer 5 u2032 tctgatgggtgtacactctg 3 u2032 seq id no 14 expression of oct 4 mrna is detected at three embryo stages 8 cell morula and blastocyst oct 4 protein expression is first detected at the morula stage.