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PubMed1988

Connective tissue remodelling in the ovine cervix during pregnancy and at term.

Cervical ripening and dilation in the ewe has been quantitated in terms of the connective tissue content of the tissue and the biosynthesis of the macromolecular components which make up the extracellular matrix of this tissue. During pregnancy there is a marked increase in the total tissue mass of the cervix along with the total mass of hydroxyproline (collagen) and hexuronate (proteoglycans and hyaluronate). The concentration of hydroxyproline of the cervix based on wet weight of the tissue decreases during pregnancy, however if based on dry weight, the concentration does not change until term. The hexuronate concentration based on both wet and dry weight of the tissue declines with pregnancy. The biosynthesis of collagen does not change during pregnancy but the rate of hyaluronate and proteoglycan synthesis by the cervix is increased in late pregnancy, and at term the rate of proteoglycan biosynthesis is elevated 10-fold. These data suggest that during cervical ripening and dilation a highly dynamic metabolic state exists within the tissue which allows for rapid tissue remodelling.

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PubMed1984

Pregnancy-related changes in the connective tissue of the ovine cervix.

During the course of gestation, changes in the metabolism and chemical composition of the cervical connective tissue occur. The concentrations of collagen, proteoglycan and hyaluronate in the cervix decrease with time of pregnancy, while there is a small but significant increase in tissue hydration. The collagen network loses its dense, ordered appearance and assumes a loose, frayed, disoriented structure. A small molecular weight dermatan sulphate proteoglycan with Kav = 0.48 on Sepharose CL-4B has been isolated from pregnant and nonpregnant ovine cervix. Proteoglycans isolated from dilated cervix yield a second peak at the excluded volume of a Sepharose CL-4B column which may represent a new proteoglycan species, or represent a proteoglycan monomer with larger glycosaminoglycan constituents. The rate of synthesis of proteoglycan is enhanced during pregnancy, and doubles in the time between 140 days and term (dilated). The increased rate of proteoglycan synthesis in the presence of a diminishing hexuronate concentration in the pregnant cervix is indicative of enhanced proteoglycan turnover. This may provide some insight into the mechanism whereby a new matrix with altered mechanical properties is produced, since a rapid turnover of matrix components enables a remodeling of the connective tissue framework. This reorganization of the matrix is discussed with respect to parturition.

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