The extended products are
amplified by PCR and detected with polyacrylamide gel electrophoresis
as a ladder of products with 6 base increments. In the stretch PCR
method, addition of tag sequences to the 5'-end of the forward and
reverse primers, together with the high annealing temperature,
enables us to amplify a full length of first cycle product from the
second cycle PCR. In the TeloChaser protocol, elongated products are
purified before PCR to remove possible PCR inhibitors, that is, the
carry-over of impurities from tissue extract.