الفهرس 
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Abstract
The present study was conducted to evaluate histologically and clinically the effect of pure chitosan membrane in healing in surgically induced skin defects.
Nine healthy mongrel dogs, kept in the animal house at the Physiology Department, Faculty of Medicine, Alexandria University. The dogs were kept under the same nutritional and environmental conditions. All dogs were healthy as documented by a veterinarian report. All the dogs were kept on the same balanced diet consisting of milk, broth and meat throughout the whole period of the study. Each animal received a dose of antibiotics in the form Ampicillin 25mg/kg body weight just before the operation.
All operating procedures were performed under general anaesthesia and sterile conditions in an animal theatre. Each animal was generally anesthetized via intravenous injection of Thiopentone Sodium, the dose of which were calculated on basis of 30 mg/kg body weight.
Full thickness square critical size defects 2cm x 2cm will be created in the skin of the facial region of the animals which will be divided into three groups, three dogs each according to the day of sacrifice. One defect on each side of the face. Nine defects at the right side of the face of each animal which will be filled with pure chitosan membrane (Group A study) and nine defects at the left side of the face of each animal which will be left to heal by itself (Group B control).
Each animal received the same course of antibiotic Ampicillin 25 mg/kg body weight for five days after surgery every eight hours. Anti-inflammatories and analgesics were given in the form of Ketolac subcutaneous to the animals every eight hours for the first three days.
The animals were sacrificed by giving them an overdose of Thiopentone Sodium. Three dogs were sacrificed in 5, 10 and 15days after the surgery, to be total nine dogs. Before sacrifice the wounds have been photographed to assess wound closure percent later on. The skin specimens were taken from dogs and they were fixed in 10% neutral buffered formalin for 24 hours. The sections were processed and embedded in paraffin wax. Longitudinal serial sections were prepared to be stained with Hematoxylin and Eosin (H & E) and Trichrome stains for histological evaluation.
H&E stain was used for general examination to evaluate granulation, angiogenesis and connective tissue arrangement and formation, while the Trichrome stain was used for evaluation of collagen formation.
The clinical evaluation
Grafted sites showed more wound closure percent in comparison to non-grafted sites. Two none grafted sites showed sepsis even though the grafted site in the same dog showed no sepsis.
The histological evaluation showed
The study groups which were grafted by chitosan showed early angiogenesis, well connective tissue arrangement, less inflammation, less oedema and by time showed migration of squamous cells over the chitosan membrane to close the defect in comparison to non-grafted sites.
At the end of the experimental period, the grafted sites showed faster healing with less scar formation and less inflammation in comparison with the non-grafted sites.