A Model to Study Gland Regeneration/Development in Rat: The Expression of Metalloproteinase- 9 and Extracellular Matrix Proteins

A model to study gland regeneration as a similar phenomenon to gland development is proposed. This study evaluated the expression of metalloproteinases (MMPs), laminin (LN) and type I and III collagen in the regeneration of the rat submandibular gland (SMG). Eighteen 30-day-old Wistar male rats were anesthetized, and the lower third of their SMG left lobe was excised. The animals were killed on the 2nd, 3rd, 7th and 15th postoperative days, and their SMG lobes were removed, fixed and processed in paraffin. Immunohistochemistry was used to label type I and III collagen, laminin, and MMP-9. The avidin-biotin technique was used, and the reaction was developed with diaminobenzidine. On the 2nd day, MMP9 expression was intense in the margins of the regenerating area and inside striated duct cells in the preserved gland. On the 3rd day, duct cytoplasm labeling persisted and was more intense than in the surrounding mesenchyme, where labeling increased along time. Concurrently, LN labeling in the basal lamina of epithelial buds was intense and discontinuous. Types I and III collagen were present during the whole process, which showed their importance for the regeneration process. The behavior of extracellular macromolecules observed in this study is similar to their behavior in gland development.