Role of host and donor cells. By implanting in transgenic rats we can distinguish between donor and host with a hPLAP immunohistochemical staining. Overview of the implanted scaffold in which bone and bone marrow can be observed on hematoxilin-eosin A) and von Kossa (B) staining. All osteoblasts are stained red indicating they are from the host (C). The osteocytes however embedded in the bone are of both host (arrowheads) and donor origin (arrows).