As you like it, Part 3: A critique and historical review of calcification as seen with the electron microscope.

As You Like It, Part 3, is a continuation of the lectures given by the author (Ultra Path VIII and Ultra Path IX). It is a critical historical review of topics of interest to electron microscopists, attempting to show what went wrong and perhaps also why. The topics chosen this time demonstrate the prominent role electron microscopy has played in elucidating the diverse ways in which calcification can occur. The classic concept of dystropic and metastatic calcification is now inadequate to explain all observed phenomena. The electron microscope shows that calcification occurs in many different intracellular and extracellular sites and that each has its own morphology and etiology. Thus, a new classification based on ultrastructural morphology is born, but few seem to be aware of it. The author examines the ubiquitous but not too well-known phenomenon of cell remodeling, which often, but not always, leads to calcification. Topics are presented under the following headings: (1) matrical lipidic debris, (2) spherical microparticles, (3) matrix vesicles, (4) intramitochondrial calcification, (5) intralysosomal calcification, (6) calcification of collagen, (7) calcification of elastic fibers, and (8) calcification of secretory products.