Fig. 1

Masson’s trichrome staining of a section of a mandibular osteosarcoma developed in an NMRI-nude mouse (HOS1544 model) in a frontal view (left, original magnification (OM)). Note the large tumor (T) with local invasion of the cortical and medullary mandibular bone (MB), and substantial central tumor necrosis (black arrows) (right, OM × 5). The osteoblastic tumor cells present with several mitoses and produce intercellular osteoïd substance (window, OM x 20)