Development of gingival overgrowth during daily long-term cyclosporine A treatment was studied in 2-yr-old beagles. Gingival enlargement developed in five of 12 dogs (42%), primarily in the mandibular anterior area. The earliest gingival changes occurred by 3 wk as an increase in the size of the interdental papillae. The lesions progressively became more severe, in some cases obscuring portions of teeth by wk 6. The redundant tissue exhibited an increase in connective tissue components and an inflammatory infiltrate primarily of plasma cells. Severity of the overgrowth varied in responding animals; both incidence and severity were related to the CSA concentration in blood. The mean CSA blood levels of responders were significantly greater than nonresponders at wk 3, 6 and 10. Since beagles develop gingival overgrowth similar to humans, they provide an excellent model to investigate the roles of local and systemic factors in the induction of gingival overgrowth.
The first mandibular molars of the Swiss albino mice, 1 through 4 days of age, were fixed in glutaraldehyde or Karnovsky’s fixative. The tissues were postfixed in Os04, dehydrated and embedded in Epon. The prepolarizing, polarizing and secretory odontoblasts were described. The prepolarizing cells, located in the vicinity of the cervical loop, were mesenchymal-like in morphology. The cells of the polarizing stage possessed organelles indicative of protein synthesis. The nucleus was located proximally. Aperiodic fibers were evident in the wide basement membrane. The secretory odontoblasts were long, slender, polarized cells closely adjoining one another. Each odontoblast possessed six morphologically discernible regions: (1) an infranuclear region, limited in size and containing few cellular organelles; (2) a nuclear region, housing the oval nucleus and a few associated lamellae of rough endoplasmic reticulum as well as a limited number of mitochondria; (3) a supranuclear rough endoplasmic reticulum region, possessing an abundance of these organelles as well as some mitochondria and secretory vesicles; (4) a Golgi region, occupying the middle third of the cell, housing the elements of an extensive Golgi apparatus which was surrounded by peripherally located profiles of rough endoplasmic reticulum; additionally, this region contained smooth endoplasmic reticulum, mitochondria, numerous secretory granules and vesicles and occasional intracellular collagen fibers; (5) an apical rough endoplasmic reticulum region, containing a rough endoplasmic reticulum component that was less extensive than its supranuclear counterpart; in addition, this region was the one richest in mitochondria and contained a plethora of secretory vesicles and granules; (6) the odontoblastic process, a region mostly void of organelles, containing various secretory products, some of which appeared to be in the process of being released extracellularly into the surrounding dentin matrix.
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