The "spindle-shaped Body" in Fibroblasts

In a recent study of the fine structure of normal uninfected fibroblasts from regenerating tendon, periarticular granulation tissue (rabbit), and various other tissues (human, chicken, hamster), Movat and Fernando (1) have described a cell organelle not yet found elsewhere. This organelle is spindle-shaped and occurs irregularly within the cytoplasm, mainly in the Golgi region and in the peripheral portion of the cell. The inner structure of the organelle is apparently fibrous, bundles of fibrils being enveloped in a sheath or membrane. Staining of the cells with phosphotungstic acid showed that the fibrils had a high electron opacity, whereas the sheath or membrane possessed a lower affinity for the stain. The so called "spindle-shaped body" measures 500 to 600 A by 2,500 to 3,000 A. The function of these bodies is not known. However, their relation to secretion has been presumed. Another presumption, that these organelles may be phagocytosed collagen, could not be confirmed since no cross-banding has been detected by the staining technique employed. In our current studies on the reproductive cycle of Rous sarcoma virus (RSV) in chicken fibroblasts, we have only once encountered cell organelles similar to the "spindle-shaped body" described by Movat and Fernando. I t is of general interest to compare, in respect to occurrence and fine structure, the "spindle-shaped bodies" described by these authors with the organelles we have found in cultured chicken fibroblasts.