First immunohistochemical evidence of human tendon repair following stem cell injection: A case report and review of literature

Figure 3 Histological and immunohistochemical analysis of a representative section from the first part of the biopsy that was investigated in this study. A: Immunohistochemical detection of type I collagen, showing the following 5 different regions (high-power photomicrographs are provided in Figure 2): ¹Organized, slightly undulating type I collagen and high cell density; ²Organized type I collagen with discernible crimp arrangement and a few cells; ³Organized type I collagen with discernible crimp arrangement and almost complete absence of cells; ⁴Almost complete absence of immunolabeling for type I collagen and a few, rounded cells; and ⁵Almost complete absence of immunolabeling for type I collagen but a high cell density; B: Corresponding polarized light microscopic image of the same field of view. Note the clear difference in collagen fiber birefringence between regions 1 and 2, and the absence of collagen fiber birefringence in regions 4 and 5.