The development and hormonal response of the autotransplanted interpubic joint in mice

The ventral portion of the immature pelvis of 12‐day‐old female mice, consisting of the interpubic cartilage and the angles of the pubic bones, was excised and either autoimplanted into its original pelvic site or autotransplanted to the thoracic region. Half the number of mice with pelvic implants and half with thoracic transplants received subcutaneous injections of estrogen and relaxin prior to necropsy. All were sacrificed at 63 days of age. All the pelvic implants and the majority of thoracic transplants were present at necropsy. The grafts from the untreated mice were similar to the intact pubic symphysis ofa 63‐day‐old mature mouse both in size and morphology. The grafts from the hormone‐treated mice had undergone a pregnancy‐type response of cartilage transformation to ligamentous tissue and resorption of the medial ends of the pubic bones. The possible significance of the cells of the interpubic joint in its response to hormones is discussed.