title: [Three-dimensional analysis of human chorioamniotic membranes structure in term pregnancy].
abstract: 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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Departamento de especialidades médicas, Instituto Nacional de Perinatología Isidro Espinosa de los Reyes, México, DF.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Vega Sánchez
authors.forename: Marisol
authors.initials: M
authors.lastname: Castillo Castrejón
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Hornelas Orozco
authors.forename: Nardhy
authors.initials: N
authors.lastname: Gómez López
authors.forename: Jorge
authors.initials: J
authors.lastname: Beltrán Montoya
authors.forename: Felipe
authors.initials: F
authors.lastname: Vadillo Ortega
mesh_terms: D000650:Amnion / Q000648:ultrastructure*; D002823:Chorion / Q000648:ultrastructure*; D003094:Collagen / Q000648:ultrastructure; D005260:Female; D006801:Humans; D007743:Labor, Obstetric; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D011247:Pregnancy
chemical_list: D003094:Collagen