Thesis (M.sc.)-Cairo nivsersity,2022.

Includes bibliogriphical references.

The present study was designed into 2 main stages, Stage I, 3 full term pregnant bitches (58-63days) were used as amniotic membrane donor. The preparation steps of amniotic membrane was performed then preserved in refrigerator 4°c temperature. The method of fresh amniotic membrane storage retained the morphological CHARacteristics (basement membrane and stromal matrix) and epithelial cells viability which is usefully used as a potent source of stem cells and biological scaffold in regenerative therapy as in allograft. Meanwhile, cryopreserved amniotic membrane held its morphological CHARacteristics, it lost the viability of the epithelial cells so it is recommended to use as a biological scaffold in cases with risk of rejection due to antigenic load of the tissue as in xenograft. Stage II, 9 mongrel male dogs were divided into 3 groups each group contain 3 dogs. 1st and 2nd groups dogs were subjected to Surgical induction of gastric and colonic wall defect then treated with amnioticmembrane allograft, 3rd group used as control group. Amniotic membrane as a substitute of the stomach and colon of dogs is beneficial in regenerative therapy. The idea of the substitution is to maintain gastric and colonic wall integrity, enhance the stomach and colon capacity.. The present study is aimed to investigate the utilization of dog’s amniotic membrane as a gastric and colonic wall substitute and evaluation of its implantation by the diagnostic aids including ultrasonographic, endoscopic, and histopathological examination and biochemical evaluation. from the present study, it could be concluded that using the fresh amniotic membrane as a type of regenerative therapy for treatment of stomach and colon defect in dogs had a significant impact as a novel method for achieving optimum reconstruction of the gastric and colonic wall and restoration its normal structure and function. The study proved that the histopathology of the epithelial lining of the stomach and colon have been regenerating, as well as the regeneration of the smooth muscle fibers under the amniotic membrane which acted as scaffold of this growth, the results of the study confirmed the reduction of inflammatory cells in the healing area between the implanted membrane and the excised part of the gastric and colonic wall. And this has been proven experimentally possibility of grafting the amniotic membrane which surrounding the embryos to the stomach and colon of dogs after excision part of it whereas the growth of the stomach and gastric epithelium and muscles was naturally without any complications of rejection the membrane with its acceptance as an alternative substances of the stomach and colon in dogs. Keywords: Am