Alveolar soft part sarcoma. An elaboration of a three-dimensional configuration of the crystalloids by digital image processing

As an initial step to elucidate the nature of the unique characteristics of the crystalloids of alveolar soft part sarcoma, a three-dimensional model of the crystalloids was prepared by digital image analysis of electron micrographs by computer. It was revealed that occult periodicities are present at two intervals, 60 Å and 380 Å, in the filamentous structure of the crystalloid; and it was also revealed by the observation of each cross-section that two globular substances with a diameter of 60 Å are arranged in dumbbell pattern in each filamentous structure. The model prepared based on these data showed the double strands crossing each other at intervals of 380 Å, each of which consists of successive arrangement of the globular substances with a diameter of 60 Å. This structure is clearly similar to that of actin. The similarities and differences between these results and the well-known studies of the organization of naturally occurring actin bundles are discussed.