Fig. 1
![Fig. 1](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs12885-022-09431-5/MediaObjects/12885_2022_9431_Fig1_HTML.png)
Histopathological examination of the inoculation site of NOD SCID mice injected with hUC-MSCs (HE staining, 10 ×). A Animals in Group 1 were euthanized, and no obvious abnormalities were seen at the inoculation site. B Animals in Group 2 were euthanized, and tumor nodules with central necrosis were observed at the inoculation site. C–H Animals in Groups 3, 4, 5, 6, 7, and 8 were euthanized. The stem cell mass at the inoculation site was necrotic, and the surrounding tissues exhibited fibroblastic proliferation accompanied by lymphocyte infiltration