Figure 12. Pathological morphology of the thymus after transplantation of umbilical cord mesenchymal stem cells. Note: (A, B) show immunofluorescence staining of thymus tissue CD4 and CD8 cells in the treatment group. (C, D) show immunofluorescence staining of CD4 and CD8 cells in the thymus tissue of model control mice. (E, F) show immunofluorescence staining of CD4 and CD8 cells in the thymus tissue of young control mice. CD4 is red, and CD8 is green. The number of CD4+ and CD8+ cells in the thymus of the model control mice was small.