Localization of fibrillin-1 in human endometrium and decidua during the menstrual cycle and pregnancy.

We have examined the existence and distribution of fibrillin-1 within the endometrium and decidua to ascertain the effect of decidualization upon its synthesis, and its relationship to other extracellular matrix proteins. Formalin-fixed, paraffin-embedded tissues were stained using monoclonal antibodies to collagen IV, elastin, fibrillin-1 and laminin, by immunocytochemistry. Fibrillin-1 was present throughout the menstrual cycle and appeared to be cell-associated. Similar staining for fibrillin-1 was detected within the Fallopian tube of ectopic pregnancy material. In first trimester, second trimester and term decidua, staining for fibrillin-1 was more intense than that during the menstrual cycle and was detected as a thick layer encapsulating decidual cells, but also in fibrillar form inter-connecting these cells. In comparison with the association of collagen IV and laminin with all basal laminae, fibrillin-1 was absent from the vascular and glandular elements of pregnancy endometrium. Elastin was absent in all tissues examined. Hence, fibrillin-1 exists within the uterus in association with basal lamina components rather than with elastin-containing fibrils, where its presence in the endometrium and decidua could be of functional significance.