*2.2. Microscopic Evaluation*

Epidermis maintained a normal architecture in both groups (Figure 5). No histological signs of malignancy were observed. The rhGH group showed thicker skin compared to the control group (1953 ± 457 μm versus 1060 ± 208 μm; *p*-value = 0.03) in the repaired area (Figure 6). This increase in the dermal layer was mainly due to a higher number of cells and the increase of extracellular matrix (rich in amorphous material). An increased in collagen deposition and a greater number of inflammatory cells were observed in the rhGH group.

*Int. J. Mol. Sci.* **2019**, *20*, 4157

**Figure 5.** Histological analysis (H&E at 50 ×, panoramic view) of the rhGH group and the control group after complete healing of the pressure ulcer. Bar = 200 μm.

**Figure 6.** Histological analysis (Masson's trichrome at 200 ×) of the rhGH group (left) and the control group (right) after complete healing of the pressure ulcer. Note the thicker dermis in the rhGH group. Bar = 50 μm.

The rhGH group presented an important decrease of collagen type I compared to the control group (16.8 % ± 4.4 versus 76.8 % ± 16.5; *p*-value < 0.01) and an increase in collagen type III (64.4 % ± 3.8 versus 70.8 % ± 2.8; *p*-value = 0.04) at wound closure (62 days, range 60–70) (Figure 7, Table 1).

**Figure 7.** Immunohistochemical expression of collagen type I (160 ×) and III (250 ×) in the rhGH group (left, **a** and **c**) and the control group (right, **b** and **d**). Bar = 50 μm.

**Table 1.** Percentage of protein expression (collagen type I and III) in the total area of tissue samples (the rhGH(recombinant human growth hormone) group and the control group).

