Collagen Changes in Rat Cervix in Pregnancy--Polarized Light Microscopic and Electron Microscopic Studies

Abstract

The structural arrangement of collagen fibers in cervical ripening was studied in normal pregnant rats by picrosirius red staining and polarized light microscopy. The macromolecular arrangement of collagen fibers in the cervices of nonpregnant controls and in firm and rigid cervices of rats in early pregnancy (1-10 days of gestation) were optically anisotropic and had birefringence and a positive sign of elongation when examined by polarized light microscopy. The findings indicated that the structure of these collagen fibers was assembled from well-packed parallel collagen molecules. The direction of fibrous formation was arranged with regularity. In contrast, most of the collagen fibers in the soft cervices were optically isotropic. The fibers were fragmented and had a structure with discontinuous birefringence. Disarray and disorientation of the collagen fibers was found in the soft cervices. These collagen fibers changed their direction of formation. The disorganization of these collagen fibers might have a major impact on weakening the tensile strength of the cervix. Thus, we conclude that the processes of rearrangement of collagen fibers might be an important process in the cervical ripening. Electron microscopic studies suggest that in the focal hydrolytic processes of collagen and other matrix components degradation by lysosomal and phagosomal vesicles were associated with atrophic smooth muscle cells and fibroblasts of the cervices. Hydrolases released from lysosomes from these apoptotic cells may presumably be one of the processes in the remodeling of collagen structure.

Second harmonic generation imaging as a potential tool for staging pregnancy and predicting preterm birth

“…A similar region of circumferential collagen fibers, interspersed with smooth muscle cells and fibroblasts, is identified in the cervix of pregnant rat by picosirius red staining and by polarization microscopy. 32 In rat, the disappearance of this ring of collagen at later stages of pregnancy is accompanied by apoptosis of both smooth muscle cells and fibroblasts. 41 In addition, we observed an accumulation of punctate SHG signal in the backward-detected images as pregnancy progressed.…”

Effects of Progesterone on iNOS, COX-2, and Collagen Expression in the Cervix

“…The human cervix is clinically soft several weeks before parturition, but remains closed with a high tensile strength, possibly because of the length or orientation of the collagen fibers (Yu et al 1995). Our studies show that in the rigid cervix (Figure 2; estrus, day 14, postpartum 3), collagen is oriented as bundles of long fibers, suggesting a high tensile strength (Vidal et al 1982;Leppert and Yu 1994;Yu et al 1995;Shi et al 1999). This is lost late Figure 8 (A) iNOS and COX-2 mRNA expression in rat cervical tissues treated on day 17 with Onapristone (antiprogestin, ZK98299).…”

Sensitivity of Raman spectroscopy to normal patient variability

“…This variance may be correlated with number of pregnancies and type of delivery (vaginal or caesarean), both of which may change the concentration and organization of collagen. 58 In the future, comparing groups of patients to different delivery types and number of pregnancies may increase accuracy rates.…”