Laser scanning-based tissue autofluorescence/fluorescence imaging (LS-TAFI), a new technique for analysis of microanatomy in whole-mount tissues.

Intact organ structure is essential in maintaining tissue specificity and cellular differentiation. Small physiological or genetic variations lead to changes in microanatomy that, if persistent, could have functional consequences and may easily be masked by the heterogeneity of tissue anatomy. Current imaging techniques rely on histological, two-dimensional sections requiring sample manipulation that are essentially two dimensional. We have developed a method for three-dimensional imaging of whole-mount, unsectioned mammalian tissues to elucidate subtle and detailed micro- and macroanatomies in adult organs and embryos. We analyzed intact or dissected organ whole mounts with laser scanning-based tissue autofluorescence/fluorescence imaging (LS-TAFI). We obtained clear visualization of microstructures within murine mammary glands and mammary tumors and other organs without the use of immunostaining and without probes or fluorescent reporter genes. Combining autofluorescence with reflected light signals from chromophore-stained tissues allowed identification of individual cells within three-dimensional structures of whole-mounted organs. This technique could be useful for rapid diagnosis of human clinical samples and possibly the effect of subtle variations such as low dose radiation.