Further evidence of a decorin-collagen interaction in the disruption of cervical collagen fibers during rat gestation,

Objective: Our purpose was to determine the histologic distribution and expression of decorin in rat cervix throughout the course of rat gestation and to correlate the findings with the known progression of collagen fiber disruption and cellular turnover in this tissue. Study Design: Cervices from pregnant animals at 5, 11, 18, and 21 days were studied. A proteoglycan of low molecular weight, decorin, was detected by sensitive and specific immunohistochemical analysis with a biotin-avidin horseradish peroxidase method. Results: Decorin was not detected on day 5. By day 11 moderate decorin staining was detected in the subepithelial layer and in the deep stroma. Decorin staining progressed to a strong expression in the subepithelial layer and to a moderate expression in the deep stroma on day 18. On day 21 (term in rat) the staining was fairly homogeneous throughout the connective tissue stroma. Conclusion: These findings clearly demonstrate that decorin expression increased progressively throughout pregnancy and are consistent with the hypothesis that an excess of decorin near term is capable of initiating a decorin-collagen interaction that leads to collagen fibril disruption and decreased cervical tensile strength. (Am J Obstet Gynecol 2000;182:805-12.)