Second-harmonic generation (SHG) microscopy is a recently developed nonlinear optical imaging modality for imaging tissue structures with submicron resolution and is a potent tool for visualizing pathological effects of diseases. In this letter, we present our investigation on the influence of van Gieson's (VG) alcoholic picrofuchsin staining on SHG in type I collagen (from tendon-rich C57BL/6). Multi-channel imaging and spectra analysis show that the strong SHG signal produced in fresh collagen type I fiber has been greatly suppressed after VG staining, which indicates that staining may induce the structural or characteristic changes of SHG-dependent crystal formed by collagen constituents, such as glycine, proline, and hydroxyproline.

Yin-yang concepts of traditional Chinese medicine (TCM) for TCM objects such as whole body, five zangs or six fus are widely used to discuss cellular processes. In this paper, the concept of the degree of difficulty (DD) of a process was put forward to redefine yin and yang and extend TCM yin-yang model to DD yin-yang model. It was shown that healthy cells are in DD yin ping yang mi so that there is no photobiomodulation, and there is photobiomodulation on non-healthy cells until the cells become healthy so that photobiomodulation can be called cellular rehabilitation.