## 2 Results  
### Histological Examination  
In patients from group A (micro-needle mesotherapy + 98.2% snail mucus), before the application of snail mucus products, collagen fibers were visible in the papillary layer of the dermis. In addition, the collagen fibers were less packed, and they were thinner and irregularly distributed (Figures 1A and 2A). Thicker collagen fibers were visible in the skin of patients after the application of the snail mucus preparation, which formed and arranged in thin bundles in the corresponding part of the dermis. Similarly, in the reticular layer, formed by irregular connective tissue, the collagen fibers bundles consisted of fibers with a slightly wavy arrangement, not adjacent to each other in bundles.  
In the skin, thicker collagen fibers formed and arranged in thin bundles were visible in the papillary layer of the dermis after the application of the snail mucus preparation. In the reticular layer of the dermis, bundles of collagen fibers were clearly visible, with a solid structure. In addition, more fibroblasts, responsible for the synthesis of all components of intercellular substance, including collagen fibers (Figures 1B and 2B), were visible in this layer after the care treatments were applied.  
Also, in patients from group B (micro-needle mesotherapy + 0.9% NaCl solution) (Figures 1C,D and 2C,D) and group C (needle-free mesotherapy + 98.2% snail mucus) (Figures 1E,F and 2E,F), similar alterations in collagen fiber thickness were found before the treatment series and 3 months after the treatment series.  
Figure 1: Skin of patients before and after 3 months of treatment. (**A**,**B**) Micro-needle-mesotherapy + snail mucus 98.2%; (**C**,**D**) micro-needle mesotherapy + NaCl; (**E**,**F**) needle-free, mesotherapy + snail mucus 98.2%. Black arrows indicate collagen fiber bundles; H-E staining; obj. magn. 40\(\times\). Scale bar: 100 \(\mu\)m.  
The next step in the morphological assessment was the evaluation of reticular fibers (Figures 3A-F and 4A-F). In group A, more reticular fibers were visible in the skin after the application of natural snail mucus, with their characteristic location in the papillary layer just below the epidermis, as well as in the reticular layer of the dermis (Figure 3B). The reticular fibers stained black with silver salts. Similar results were observed in the group of patients who received micro-needle mesotherapy with 0.9% NaCl solution and in patients who received needle-free mesotherapy with 98.2% snail mucus.  
Figure 2: Skin of patients before and after 3 months of treatment. (**A,B**) Micro-needle mesotherapy + snail mucus 98.2%; (**C,D**) micro-needle mesotherapy + NaCl; (**E,F**) needle-free mesotherapy + snail mucus 98.2%. Yellow arrows indicate collagen fiber bundles; Mallory Trichrome staining; obj. magn. 40\(\times\). Scale bar: 100 μm.  
Figure 3: Skin of patients before and after 3 months of treatment. (**A**,**B**) Micro-needle mesotherapy + snail mucus 98.2%; (**C**,**D**) micro-needle mesotherapy + NaCl; (**E**,**F**) needle-free mesotherapy + snail mucus 98.2%. Black arrows indicate reticular fibers; AgNo3 staining; obj. magn. 40\(\times\). Scale bar: 100 \(\upmu\)m.  
Taking into account the amount of reticular fibers, our results indicate that the two methods of application of snail mucus and the application of 0.9% NaCl with micro-needle mesotherapy resulted in similar effects.  
More elastic fibers were observed in the three study groups in patients 3 months after the series of treatments compared to the skin before the treatments (Figure 5). However, the greatest accumulation of elastic fibers in the dermis was observed in patients who received a series of needle-free mesotherapy treatments with 98.2% snail mucus (Figure 5C).  
Figure 4: Skin of patients before and after 3 months of treatment. (**A,B**) Micro-needle mesotherapy + snail mucus 98.2%; (**C,D**) micro-needle mesotherapy + NaCl; (**E,F**) needle-free mesotherapy + snail mucus 98.2%. Picro Sirius Red staining; obj. magn. 40\(\times\). Scale bar: 100 \(\upmu\)m.