Abstract
Microscopic examination of intestinal neurovascular tissues is a valuable diagnostic tool to evaluate intestinal diseases. However, the standard microtome-based 2-dimensional histology provides only limited perspective of the dispersed intestinal tissue network in space. To provide a global view of the network structure, in this research we employed optical clearing to generate transparent tissue specimens for penetrative 3-dimensional (3-D) visualization of the intestinal architecture. Qualitative and quantitative analyses were developed to characterize the 3-D intestinal networks in health and disease. In this thesis we acquired the human intestinal tissues from surgical resection for intestinal diseases. Both normal and diseased tissues were included in analysis. Nuclear and immunostaining of the tissue specimens were employed to reveal the intestinal microstructure and tissue networks. Afterward, optical clearing was used to generate transparent intestinal specimens, which led to panoramic visualization of the tissue networks up to 300 μm in depth via confocal microscopy with subcellular resolution. Spatial projection, analysis and quantitation were performed using the 3-D analytical software Avizo. Significantly, preparation of transparent human intestinal specimens by optical clearing led to less fluorescence signal decay in confocal microscopy, achieving higher signal-to-noise ratio of the acquired images (Chapter B). The 3-D vascular and innervation patterns in association with their microstructures were constructed at both the intestinal mucosa and wall. In addition to the neurovascular structure, in colon microscopy we also acquired the 3-D structure of the interstitial cells of Cajal (ICC) to delineate their morphological patterns (Chapter C). For the diseased tissues, in this thesis we examined the vasculature and glial network in colorectal carcinoma and differentiate their morphological and quantitative differences in comparison with those in the normal human colon mucosa (Chapter D and E). Finally, to analyze the association between the intestinal tissue networks, we examined the association of ICC with the microvascular network in the human colon wall via high-definition 3-D microscopy. A new subclass of ICC, the peri-capillary ICC, is proposed and qualitatively and quantitatively characterized to highlight this unique cell population (Chapter F). In sum, the microscopic and illustration methods/approaches developed in this research highlight the technical advance in 3-D gastrointestinal histology. The morphological and quantitative information of the intestinal tissue networks will lay the foundation for future study of the intestinal physiology and pathophysiology.