[Three-dimensional analysis of human chorioamniotic membranes structure in term pregnancy].

Background: Physical and structural chorioamniotic membranes integrity is due to a precise process of synthesis and degradation of collagen; surrounding collagenolitic activity raises during labor, what leads to a structural loss and mechanical resistance weakening, the main cause of its rupture under physiological and pathological conditions. Understanding of its three-dimensional structure is essential to characterize normal and pathological labor.
Objective: To analyze three-dimensional structure of human chorioamniotic membranes at gestational term.
Material and Methods: Descriptive study to analyze the distribution of collagens type I, II and IV in human chorioamniotic membranes at term (37 to 40 gestational weeks) without labor by means of confocal and electronic scan microscopy.
Results: Cells' amnios shapes a homogeneous epithelium without a close intercellular contact (classic epithelium) what may contribute to transmembranal diffusion molecules' transport. Amnios connective tissue is too a complex fibrilar net of type I collagen, structurally supported by type IV collagen. On the contrary, corion has a great amount of cells in close contact, with a few fibers of type I and II collagen, and almost none of type IV collagen cells.
Conclusion: Three-dimensional analysis of chorioamniotic membranes connective tissue, particularly amnios, allows to understand the main role of type IV collagen on supporting its structure, as well as collagenolitic enzymes in its degradation and rupture under normal and pathological conditions.