Appearance and ultrastructure of intranuclear crystalloids in tendon fibroblasts induced by an anabolic steroid hormone in the mouse.

The appearance of intranuclear crystalloid formations in tendon fibroblasts is described during enhanced protein synthesis. The enhanced protein synthesis was induced by an anabolic steroid hormone. One type of these crystalloids consists of closely packed bundles of filaments, 8-10 mm in diameter arranged in parallel. The other type of intranuclear crystalloids possesses an architecture similar to honeycomb pattern. Both of these paracrystalloid nuclear inclusions seem to be an indicator for an extremely enhanced protein synthesis in these cells after the administration of anabolic steroid hormones. Their numerous descriptions in the literature on hypertrophic or precancerously modified tissues and their increased occurrence under pathological influences both point to this explanation. In this way we now possess for the first time a model for experimental on intranuclear crystalloids of tendon fibroblasts.