Comparison Study Of Wound Healing In Fetal,Doe And Adult Rabbits

Skin wound healing in the adult usually results in a collagenous scar or hypertrophic scar that are difficult to treat and prevent. The mechanism underlying scar and hypertrophic scar formation and effective measure accelerating wound healing and the same time alleviating scar formation are still the significant problems in the field of surgery. Studies in the last two decades show that fetal surgical skin wounds heal rapidly and without the scarring and inflammation. Understanding the mechanism underlying fetal scarless wound healing will help us to solve the contradiction of accelerating wound healing and the same time alleviating scar formation in the field of surgery. To achieve this aim, we still have a lot of to do.First of all, we established a fetal rabbit scarless wound healing model. The key to progression of the experimental lies in keeping the rate of the fetal survival after surgery in the 80 percent range. In this paper a simple method of experimental on the fetus of the rabbit on day 22-23 of pregnancy (term=31-32days) is described. Intravenous thiopental sodium is used for anesthesia. A fetus is partially removed from the uterus for the experiment and then return, or proper area to be operated on is exposed through the hysterotomy for the experimentation. Amniotic fluid is restituted by instillation of warmed saline at 37℃. special care is taken to suture the amnion. While these techniques are carefully carried out, we have an operative success above 90 percent. A technically simple procedure has been developed.Using this fetal rabbit model, a 1.5cm linear wound was created in one fetus and a 1.5cm silicon tube was placed subdermally in an other fetus in the same doe. After 2,3,5 and 7 days, specimen were harvested. By histological and TEM (transmission electron microscopy) examinations, we found that the fetal linear wounds differ markedly from adult wounds in rapid healing, no acute inflammation, no scarring, and an early and no excessive collagen deposition.Following creation of a surgical wound in fetal and adult rabbits, at different intervals the healing wounds were harvested and analyzed for total collagen content (dry tissues) using quantification of hydroxyproline content assuming that collagen contains 12.5% hydrowyproline and the ratio of type III/type I. Collagen using SDS-coomassie brilliant blue cellulose acetate electrophoresis . we found that the total collagen in the adult rabbits is about three or four times to the fetal rabbits. The prominent collagen type in fetal skin is type III collagen. As the fetal developing, the ratio of type III/type I collagen decreased. The average proportion of type III collagen was elevated in normal (55.35%⁴4.10%) as well as wounded fetal skin (63.68⁴9.03%)when compared with normal levels for the adult(25.76%)and wounded(55.02%³2.92%).Fetal skin wound is rich in glycosaminoglycan and hyaluronan. We utilize Alician Blue staining to determine the content of glycosaminoglycan and cellulose acetate electrophoresis to determine hyaluronan of uninjured skin and of wounded skin in fetal and adult rabbits (dry tissues), we examined changes occurring in the development of normal rabbit skin and of linear wound healing tissue at different stages. In the normal skin, the content of GAG and HA is about 2.5 times to the adult and maternal rabbits. Three days after wounding, the content of GAG reached its peak, approximate 84.22% of the total GAG in fetal wound tissue was hyaluronan. The content of GAG and proportion of hyaluronan keep in the same till the 7^th day. In uninjured fetal skin the contribution of hyaluronan to...