The human body is comprised of billions of cells, all working in unison to keep us alive. The gastrointestinal tract (gut) is also comprised of a network of different cell types.
What you are looking at is a 1x1 mm2 confocal image of the mouse intestine, at a resolution of 0.5 µm per pixel, which has been imaged using two-photon excitation microscopy.
The green channel illustrates the crypts in the epithelum, the red channel the capillaries and other cells. The white channel shows the collagen network.