[Fine structure of the public symphysis in the mouse]

Classical histological descriptions of the modifications of the mouse pubic symphysis (PS) during pregnancy did not take sufficient account of its structural heterogeneity. Precise morphological study of the PS, in adult male and virgin female mice, was carried out under light and electronic microscopy. Our observations on pregnant females are still imcomplete. Two regions of the PS should be distinguished according to their structure and evolution during pregnancy. The cranial region shows diarthrodial articular characteristics. This region disappears in the female during the first pregnancy and is not reconstituted after parturition. The caudal region comprises two types of cells in the female : typical chondrocytes and a peculiar cell-type whose function has yet to be defined. The latter seems to be responsible for the loose structure of the symphyseal cartilage and to contribute to the development of pseudocavities in the ligament in the final days of pregnancy. It is possible that such cells may be stimulated by relaxin and may secrete a hydrophilic factor such as hyaluronic acid.