Immunohistochemical localization of type IV collagen and laminin in the gingival capillary basement membrane of the diabetic rat.

Distribution of type IV collagen and laminin in the gingival capillary basement membrane from streptozotocin-induced diabetic rats was investigated using immunoelectron microscopy. Both type IV collagen and laminin were found throughout the basement membrane. Quantitative analysis revealed that the immunoreactive area for laminin did not change with age, and the width of laminin deposition remained constant, even when diabetes was induced in the animals. However, the immunoreactive area for type IV collagen thickened with age. Further, the width of type IV collagen in the basement membrane increased markedly 36 weeks after diabetes was induced. It was concluded that the thickening of the gingival capillary basement membrane in experimentally induced diabetic rats was due an increase of type IV collagen deposition.