Generation of Chimeras
We employ two techniques for generating chimeras from iTL ES cells, blastocyst injection and 8-cell stage embryos.
Traditional blastocyst injection results in chimera animals with variable genetic contribution from the gene targeted ES cells. iTL has a strong track record of achieving sufficient targeted ES cell genetic contribution to enable germline transmission from the 1st resulting litter.
iTL also utilizes the XYClone laser for injection of 8-cell, pre-blastocyst stage embryos. This technique presents a minimal disturbance to the embryo and generates higher percentages of targeted ES cell contribution to the resulting chimera mouse. Our Hybrid C57/129 ES cell line is robust enough to utilize the 8-cell method. However, for the C57BL/6 and 129svev ES cell lines, traditional blastocyst injection has proven more reliable in generating high percentage genetic contribution chimeras and in these cell lines is at a clearer advantage to the 8-cell injection technique.
An important point to remember when considering different injection techniques is that the quality of the embryonic stem cells is essential for positive results no matter what injection method is utilized. Lower quality or viability ES cells give negative results, no matter the injection technique used. At iTL, we prioritize and emphasize to our clients the quality of all in-house ES cells lines. Using iTL ES cells ensures high percentage chimeras and germline transmission.
