Table 1. Progressive stages of AVIC deterioration in in vitro calcification as revealed by transmission electron microscopy.
| Degenerative features | 3 days | 9 days | 15 days | 21 days | 28 days |
|---|---|---|---|---|---|
| Organelle disappearance | − | ± | +/++ | ++ | +++ |
| PPM appearance | − | − | ++ | + | − |
| PPL appearance | − | − | ± | ++ | +++ |
| EB-CS appearance | − | − | − | + | ++ |
| HA appearance | − | − | − | + | +++ |
AVIC, aortic valve interstitial cell; PPM, intracellular degradation-derived phthalocyanin-positive material; PPL, PPM-derived pericellular phthalocyanin-positive layers; EB-CS, PPL-derived extracellular blebs plus their subsequent byproducts identifiable as real calcospherulae; HA, needle-like hydroxyapatite crystals.