*4.6. Microscopic Evaluation*

Histological analysis of the human skin was performed in both groups after wound closure by two independent histologists. Samples of skin were obtained from the two groups, and they were placed in 10% buffered formaldehyde (for histopathological studies) and Bouin (for immunohistochemical studies). Then the samples were dehydrated and embedded in paraffin. Tissue sections (5 mm thick; 50 sections for each sample) passing through the central plane of each sample were stained with hematoxylin-eosin and Masson's trichrome for morphological assessment. Tissue sections were examined under a Zeiss Axiophot light microscope (Carl Zeiss, Oberkochen, Germany). The thickness of the healed human skin was measured in micrometers with Axiovision Release 4.6.3 software (Carl Zeiss, Oberkochen, Germany). The total thickness of the skin was defined as the distance between the stratum corneum and the boundary between human dermis–host mouse tissue.
