Ultrastructural, immunohistochemical and biochemical analysis of glycosaminoglycans and proteoglycans in the mouse pubic symphysis during pregnancy

At the ultrastructural level, using cuprolinic blue and enzymatic digestion by chondroitin lyases, two types of proteoglycan filaments were observed in the fibrocartilage on the 12th day, as well as in D15, D17 and D18 pubic ligaments. The only sulfated glycosaminoglycan in these filaments was chondroitin sulfate, as shown by chondroitin lyase treatment. Their electrophoretic mobility, before and after enzymatic degradation, corroborated this inference. The ratio of chondroitin sulfate/dry weight of symphysis showed two phases of increase: between D12 and D15, and between D17 and D18. We suggest that the first corresponds mainly to an increase in decorin when the ligament is formed, and the second to versican, during “relaxation”. Versican and hyaluronic acid, working as water holding molecules would be responsible for the hydration of the ligament at the end of pregnancy, allowing an increase in resiliency. The presence of hyaluronic acid was confirmed by labeling with HA-probe in the perichondrium, fibrocartilage and ligament. The role of collagen fibers as physical restrictors of the complete expansion of glycosaminoglycans and hyaluronic acid in tissue is discussed.