Biologia estrutural das fibras de colageno da sinfise e do ligamento pubiano de camundongo durante a prenhez, parto e pos-parto

AUTOR(ES)
DATA DE PUBLICAÇÃO

1998

RESUMO

The spreading apart or relaxation of the pubic joint depends on the growth of a ligament in pregnant rodents, and offers a unique system for the study of the hOl1l1onal regulation of connective tissue. The two pubic articular surfaces begin to separate on the 12th day of pregnancy, and the gap widens an average of 1 mm per day until parturition. After labor, the gap rapid1y closes by the 5th day post-partmn, but does not retum to the virgin condition. The development and involution of the pubic ligament involve an increased biosynthesis of extracellular matrix components such as collagen proteoglycans, and a new balance between synthesis and degradation. In order to evaluate and compare the collagen fibers and fibrils assembly and their possible modifications in the virgin, pregnant and post-partum mouse pubic symphysis, we perfol1l1ed a histochemicaL ultrastructural and morphometric study. The collagen network in virgin and twelve days pregnant murine symphysis showed two distinct distribution and organization: a central fibrocartilaginous region with a random meshwork of thin fibrils collagen that on 12th day of pregnancy they were oriented parallel in direction to the mechanical stretching of joint spreading; b) the peripheral region surrounded by sheaths, continuous with the periosteum, showed thick wavy fibers preferentially oriented. The ligament architecture on the 15th day of pregnancy doesn t show regional differences and was assembled by bimodal thick collagen fibrils. After 17th day of pregnancy the collagen meshwork becomes progressively loosen which result in the relaxation of the symphysis, preparing for the parturition. In the post-partmn, the gap quickly diminished and on 5th day post-partmn, the loose three dimensional collagen arrangement transfol1l1s in dense connective tissue. Therefore the histoarchitecture changes observed in the pubic symphysis during pregnancy can be attributed to the changes of collagen fibers assemblies and their rearrangement in this region preparing to the parturition. In virgin the collagen assembly is proper to resist the compression forces acting on the pubic joint, which becomes gradually relaxed due to the looseness of collagen meshwork of the ligamento This facilitates the opening for delivery but sustains the tissue integrity of the symphysis. Afier parturition the reconstitution and reorientation of the collagen fibers suggest the support for the traction fimction just to restore the pubic joint

ASSUNTO(S)

ultraestrutura (biologia) histoquimica colageno

ACESSO AO ARTIGO

Documentos Relacionados