The figure consists of four parts, Figures 13a to d, that illustrate fluorescence micrographs of GFP expression in different organisms.

Figure 13a: a micrograph shows the bell-shaped jellyfish Aequorea victoria expressing GFP. The light-emitting organs of the jellyfish express GFP and emit fluorescence at the bottom of its bell.

Figure 13b: a micrograph shows spindle-shaped HeLa cells with the nucleus at the centre surrounded by a network of endoplasmic reticulum. The endoplasmic reticulum of the HeLa cells expresses GFP and emits green fluorescence. The scale bar reads 20 micrometres.

Figure 13c: a micrograph shows three spindle-shaped worms Caenorhabditis elegans expressing GFP in neuron, which emit green fluorescence.

Figure 13d: a micrograph shows a mouse expressing GFP. The ears, eyes, and front part of the mouth express GFP and emit green fluorescence.