Electron microscopic observation of the soft tissue in the gubernacular canal. 3. Changes in the components with aging

: In the present study, we observed the epithelial remnants in the gubernacular canal of a 3-month-old crab-eating monkey by transmission electron microscopy, and compared our findings with those in a 1-year-old one. The following results were obtained: 1. The basal lamina of the epithelial remnants of the 3-month-old monkey was more clearly seen than that of the older animal, and it had a brush-like appearance probably due to relatively high forming activity. 2. No marked difference was observed among the cellular components between the two ages. The tonofilaments which were fibrous in ordinary epithelial cells already showed some aggregation and granular appearance in the 3-month material. 3. In most parts of the 3-month-old material, only a small number of atrophied cells were observed; however in the epithelial remnants located near the gingival epithelium, we observed cells containing swollen mitochondria which probably occurred due to the degeneration of the cells. 4. The density of collagen fibers around the dental germ was relatively low, whereas in the area close to the gingiva, the density of fibers was very high. 5. In the present study, no components exactly derived from the remnants of epithelial cells were observed within the extracellular spaces of the connective tissue.