Fig. 2

Two different techniques for in vivo imaging. In the procedure shown to the left, cells are isolated from organs harvested from mice, labeled with a specific dye, and transferred into mice. On the other hand, the procedure shown on the right establishes mice transgenic with the creERT2 gene and fluorescent protein targeting specific cells. The mice are then injected with the hormonal substance tamoxifen, which induces the activity-dependent expression of the fluorescent protein by Cre recombinase, allowing in vivo observation. Pros and cons for each method are listed at the lower part of the figure