However, there was a significant increase in the steady-state level of the 21 C transcript in the stage 25 heart as compared to that of the stage 15 heart. For all cloned cDNA fragments used for making anti-sense riboprobes, sense probes were also made and used as negative controls. One example is shown in Fig 9, where the 21C sense riboprobe was used. Figure 9 Whole-mount in situ hybridization of stage 15 and stage 21 chicken embryonic hearts using the sense riboprobe. There was no detectable signal found in both staged embryos.
Arrowheads point to the hearts.