Cell maceration scanning electron microscopy and computer-derived porosity measurements in assessment of connective tissue microstructure changes in the canine myxomatous mitral valve

Canine myxomatous mitral valve disease is associated with changes in the valve extracellular matrix (ECM). The aim of this study was to examine the use of cell macerated scanning electron microscopy (CMSEM) in evaluating ECM changes in a small sample of valves and to quantify these changes using computer-aided image analysis of sample porosity (a measure of structural disorganisation and collagen loss).The distinct layered structure of the de-cellularised matrix could be seen in the normal valve and there were marked changes in layers and ECM organisation as the disease progressed. Clearly visible and quantifiable, statistically significant changes were found in valve porosity across the entire leaflet thickness and particularly in the valve mid and distal zones. All of these changes are presumed to affect the mechanical function of the valve. In conclusion, CMSEM with computed image analysis can be used to visualise and measure tissue structural changes in a quasi-3-dimensional manner in normal and diseased tissues.