MPLSM/SHG imaging reveals native collagen structure in living mammary gland. A: (a) MPE/SHG image at the "top" of the mammary duct, showing both wavy and taut (straight) collagen structures as well as endogenous fluorescence from FAD in stromal cells (most likely fibroblasts and immune cells). (b) MPE/SHG image of a mammary duct demonstrating collagen wrapped around the duct as well as radiating out from the duct (as can be seen predominantly at the top of the micrograph near the end of the duct). (c) Enlarged section from (a) showing some aspects of collagen fibril structure that resemble the standard banding pattern seen in collagen fibrils from connective tissue. (d) SEM of mouse tendon mouse tendon demonstrating the ~67 nm banding pattern characteristic of collagen fibrils. (e) Correlative SEM image of collagen surrounding ductal epithelial cells showing both wavy (upper arrow) and taut (lower arrow) fibers that match the collagen structures obtained with MPE/SHG imaging. (f) MPE/SHG image of the region near the nipple in tissue demonstrating straightened collagen fibers radiating from the central ductal structure. (g) MPE/SHG image "above" the mammary duct showing both wavy and taut fiber structures. Note: all mammary tissues in A are from the B6/129 strain, which serves as the background strain for col1a1 mice. B: (a) Whole mount analysis from wild type control (top) and Wnt-1 mice (bottom), which display hyperplasia compared to wild type glands. (b,c) Histology of mammary glands from wild type control animals (b; H&E) and hyperplastic abnormal ducts from Wnt-1 mice (c; Masson's Trichrome). (d,e) MPLSM/SHG imaging of wild type control mammary duct demonstrating a ductal end (d) and branching (e). (f) MPLSM/SHG imaging of a mammary duct from a Wnt-1 mouse showing hyperplasia of the ductal structure and increased deposition of disorganized collagen. Note: All MPE/SHG images are from live intact tissues that are not fixed, sectioned, or stained; scale bar for MPE/SHG images equals 25 μm; scale bar for histology images equals 50 μm.
Provenzano et al. BMC Medicine 2006 4:38 doi:10.1186/1741-7015-4-38