Slide-free imaging of hematoxylin-eosin stained whole-mount tissues using combined third-harmonic generation and three-photon fluorescence microscopy.

Intraoperative margin assessment of surgical tissues during cancer surgery is clinically important, especially in the case of tissue conserving surgery like Mohs micrographic surgery in which minimization of the surgical area is considered crucial. Frozen pathology is the gold standard of assessing excised tissues for signs of remaining cancerous lesions. The current protocol, however, is time-consuming and labor-intensive. Instead of the complex frozen sectioning, staining, and traditional white light microscopy imaging protocol, optically sectioned histopathological imaging of hematoxylin-eosin stained whole-mount skin tissues with a subfemtoliter resolution is demonstrated by using nonlinear microscopy in this study. With our proposed method, the reagents of staining and the contrast of imaging are fully consistent with the current clinical standard of frozen pathology, thus facilitating rapid intraoperative assessment of surgical tissues for future applications. Image: Slide-free nonlinear microscopy imaging of H&E stained whole-mount skin tissue showing the morphology of sweat glands.