You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["AnatomicalEntity"].

Please return the output as a JSON object of the format: {"AnatomicalEntity": ["tumor cells", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

[An experimental study on angiogenesis of non-vascularized autogenous bone graft with vascular bundle implantation]
OBJECTIVE: To investigate the effect of vascular bundle implantation in autogenous bone graft on angiogenesis. METHODS: Thirty-six New Zealand white rabbits were evaluated in this study. A portion of bilateral radial bones of a rabbit were removed as free bone grafts, whose periostea were peeled off. In test group, the external maxillary artery bundle was passed through the marrow cavity of the bone. In control group, there was no vascular bundle implantation. Each bone was placed in masseter muscle separately. The rabbits were sacrificed and the specimens were procured at 3 days, 1, 2, 3, 4 and 6 weeks after surgery for histological observation, Chinese ink perfusion and CD34 immunohistochemistry. Microvessel density (MVD) was assessed in order to evaluate angiogenesis of autogenous bone grafts. RESULTS: The bone grafts were found revascularization in 3 days after surgery in the test group, whereas at 2 weeks in the control group. In 3 days, 1 week, 2 weeks, 3 weeks and 4 weeks after surgery, the MVD of test group was significantly higher than that of control group. In 4 weeks after surgery, angiogenesis of test group reached to peak. CONCLUSION: Vascular bundle implantation improved angiogenesis in non-vascularized autogenous bone graft in this study.
{"AnatomicalEntity": ["vascular bundle", "external maxillary artery bundle", "periostea", "bilateral radial bones", "bone grafts", "specimens", "autogenous bone graft", "masseter muscle", "Microvessel", "autogenous bone grafts", "bone", "marrow cavity", "Vascular bundle"]}