Aortic Histology and Morphometry

Aortic tissue was cut parallel to the aortic root before dehydration and embedding in paraffin to obtain optimal cross sections of the root and ascending aorta as described before^{93 (link)}. Tissue slices were cut as 7 µm thick sections using a Microm HM340E microtome (ThermoFisher). After deparaffinization and rehydration, the hematoxylin and eosin (HE) staining or Lawson’s elastin staining were performed according to manufacturer’s procedure (Klinipath). Sections were imaged on a Leica DM6B light microscope. Measurements of the aorta root and ascending aorta diameter were performed on three different sections for each sample using the measure tool of Leica Application Suite X software (Leica). Number of elastin breaks was determined by manually counting the locations that showed a break in elastin fibers on a complete preparation. Three different sections for each sample were assessed by two independent blinded observers.