Histological Observation Of Skin Scar-free Wound Healing Process In Scincella Tsinlingensis

Wound healing is the initial stage of organ regeneration,while the induced scar inhibits such regeneration.Therefore,scar-free wound healing is an active focus in the regenerative medicine.Most lizards have different tissues and organ regeneration capabilities in the tail regeneration and the limbs scar healing.For different types of lizard species,the processes of wound healing on the body and the tail are various.To explore the morphological events of the wound healing in different lizards can not only enrich the data about the wound healing mechanism of lizards,but also be beneficial to the research on evolutionary mechanism of skin regeneration of the higher vertebrates and human beings.Scincella tsinlingensis,a kind of ovoviviparous lizard,is an endemic species of China.Skin biopsies was taken on the body and tail of S.tsinlingensis with a 1.5 mm biopsy punch.Multiple techniques about morphology,histology,immunohistochemistry and scanning electron microscope were used to investigate the morphological characteristics and the cytoarchitectures in the wound healing processes of the lizards.The main results as followed:1.In the process of the body and tail wound healing of the S.tsinlingensis,the wound would twice go through the stages of shrinking,increasing and then shrinking.The wound healing speed of the body and the tail were faster at 60-80d post-wound and 20-40d post-wound,respectively.Average speed of the body and tail wound healing were 0.020±0.002 mm²/d,and 0.016±0.001 mm²/d,respectively2.From the morphologic and histological observation,the process of the wound healing of S.tsinlingensis involved four stages,hemostasis,re-epithelialization,proliferation and remodelling,which also could be subdivided into six steps.Step I,0-48h post-wounding.The hyperpigmentation existed in the wound edges,but the blood on wound surface of the body had been gradually oozed,while that of the tail had no obviously blood loss.Step?,2-10d post-wound.The exudate clot formed across the wound sites,and appeared to be thicker.Step?,7d-15d post-wound.The wrinkled wound epitheliums were formed on the wound surfaces,whose thickness was from 2 to 3 cell layers.And then,the wound epidermises of body and tail of the lizard were stratified,which had exfoliating wound epidermis.Step?,10-28d post-wound.The corneous layers of the wound epidermises were formed under the exfoliating wound epidermises.They were thicker and short of pigmentation.The tissue regeneration established a certain amount of vascular network.The skin of S.tsinlingensis was thinner than the others,and has a small amount of vascular.Step?,20-70d post-wound.The wound epitheliums became increasingly keratinized and began to form unsharp scales.The melanophores were randomly scattered in the base of the epidermises.Step?,45-135d post-wound.The complete differentiation of the epidermises,dermises,and scales.3.In wound healing step I of the tail and the body,the proliferating cell nuclear antigen immunopositive cells were increased,the data revealed that the epidermis were proliferating.The matrix metalloproteinease-9 immunopositive cells were presented in wound epithelial cells suggested that involved in the remodeling of the extracellular matrix.In wound healing step?-?,cytokeratin 6 immunopositive keratinocytes were increased,the data revealed that the epidermis were differentiating.In wound healing step?-?,the?-smooth muscle actin immunopositive myofibroblasts were presented in wound surfaces to promote wound close.And then,the neutrophils,macrophages and fibroblast demonstrated immunoreactivity for C3 that can inhibition scare formation.In wound healing step?-?of the tail and the body,numerous thrombospondin-1 immunopositive cells were observed in the wound epidermises to the inhibition of angiogenesis,and in wound healing step?-?of the tail and the body,vascular endothelial growth factor,a potent proangiogenic factor,was highly expressed to promoting angiogenesis.In wound healing step?-?,the fibroblast and vascular endothelial cells demonstrated immunoreactivity for transforming growth factor-?₃that suggested the transforming growth factor can inhibition granulation tissue formation.4.The tail and body scanning electron microscope results were similar.In wound healing step?,there were a large number of haemocytes on the body wound surfaces,which was more abundant than that in the tail.In wound healing step?-?,the wound was covered by a filamentous network that resembled fibrin.There are some bacillus in the wound surfaces in wound healing step?-?.In wound healing step?,the scanning electron microscope results suggested that regenerated scales were similar in size to mosaic pavement scales of the uninjured skin,but the microornamentation of regenerated scales was sparse and the dentalation of oberhautchen cells became passivated.In summary,the morphologic and histological observation,the skin of body and tail could scar-free wound healing of S.tsinlingensis.Immunohistochemical data revealed that the PCNA?MMP-9?cytokeratin 6??-SMA?C3?TSP-1?VEGF and TGF-?₃might play important roles in the scar-free wound healing process of skin.The tail and body scanning electron microscope results suggested that regenerated scales were similar in size to mosaic pavement scales of the uninjured skin,but there were some differences in the microornamentation structure of regenerated scales.The study provided clues to further investigate the molecular mechanism of skin scar-free wound healing process of S.tsinlingensis.