Non-Inflammatory Diseases - XV - Smooth Muscle Disarray and Lamellar Unit Loss
17 year old with marked smooth muscle disarray and lamellar unit loss. Normal aorta, young adult. Left upper image. Transverse section of the aorta shows the three layers of the wall. Intima forms the luminal surface (top), the media and adventitia. (X 50, H&E). Rright upper image. The intima is distinctly shown as paler layer than the media. The media consists of multiple lamellar units highlighted by the black lines of elastic laminae. There is an abrupt change at the boundary of the media and adventitia. The adventitia consists mostly loose fibrous tissue (yellow) without additional elastic tissue. The vasa vasorum are distinct and of normal thickness. (X 50, Movat pentachrome). Left lower image. At higher magnification the media shows distinct lamellar units with slightly more eosinophilic and refringent elastic laminae. The majority of the smooth muscle cell nuclei are seen in longitudinal orientation as this is a section perpendicular to the longitudinal axis of the aorta. (X 500, H&E). Right lower image. The lamellar units in close up. One lamellar unit can be defined as the components between two layers of elastic laminae in this image. These contents are: 1. The elastic lamina itself. 2. The extracellular matrix (fibrous tissue (in yellow) and mucopolysaccharides (green/blue). 3. Smooth muscle cells (red cytoplasm and dark blue/burgundy nuclei) 4. Another set of the extracellular matrix (described in 2 above). 5. Another elastic lamina. (X500, Movat pentachrome).
