Deep-tissue microscopy of microvessels in normal colon mucosa.

(A) Extended imaging depth in confocal microscopy with optical clearing. Upper panels show the CD34 signals of mucosal microvessels in the optically cleared mucosa, while in the opaque mucosa (lower panels, saline immersion) the signals drastically declined as the focal plane progressed into the tissue. Signal intensities are presented in grayscale, red (signal saturation), and blue (no signals). Video S1 compares the image stacks derived from the two optical conditions as the focal depth progressed from 0 to 150 μm. (B) Projection of the vascular signals derived from the optically cleared and opaque colon mucosa.