In the present study, ten healthy mature sheep and goat & six healthy suckling sheep and goat of both sexes. The reticular groove was removed rapidly from the abdominal cavity just after the slaughter of the animals. The specimens for light microscope were immediately fixed in 10% neutral buffered formalin (N.B.F.) and processed by paraffin technique. Sections of 5μm thickness were obtained. The underwent H&E , Silver impregnation technique, Crossmon's trichrome stain,Van Gieson stain, Orcein stain, Bromo phenol blue stain, AB (pH 2.5) and PAS technique. Anatomically, The gastric groove is a vital part of digestive system of suckling ruminants. The gastric groove of suckling ruminants acts as a tube transporting milk and other fluids directly from esophagus into abomasum. The gastric groove consisted of two well developed lips and floor between them. The floor of the reticular groove contained longitudinal folds which is the direct continuity and macroscopical papillae which randomly distributed at the proximal parts and clustered at the entrance of abomasum at level of reticulo-omasal orifice. Histologically, The gastric groove contoured by two lips, right and left, delimited thin floor. It is indicated that both the lips and the floor consisted of the same layers of any hollow organ ; Tunica mucosa which consisted of three sublayers; (lamina epithelialis , lamina propria and muscularis mucosa), tunica submucosa, tunica muscularis which consisted of (inner circular layer and outer longitudinal layer) and tunica serosa. The whole groove was covered by stratified squamous epithelium which arranged in form of several layer began firstly with undulant basement membrane then single layer of columnar cells with oval nuclei which called stratum basale then several layers of polyhedral cells with rounded or spherical nuclei known as stratum spinosum next these cells become more flattened with flat nuclei to be known as stratum granulosum after that a clear layer consisted of flattened cells filled with keratin known as stratum lucidum finally a layer of dead non nucleated keratinized cells known as stratum corneum. This layer is followed by lamina propria which consisted of connective tissue fibers. Muscularis mucosa of composed of thin transversely arranged smooth muscle fibers in floor and lips which were immersed in connective tissue of the lamina propria. Tunica submucosa is made up of connective tissue fibers had some aggregation of adipocytes containing blood vessels, lymph vessels and nerves. Tunica muscularis in lips and floor consisted of inner circular layer of smooth muscle fibers and outer longitudinal one. In case of adult sheep, mucous glands were found in tunica submucosa at level of lip- floor junction in the first parts of the reticular groove but it were found in tunica musculosa among smooth muscle fibers of outer longitudinal layer in lips. Mucous glands consisted of oval or round acini. These acini were made of single layer of columnar or pyramidal cells with their apices directed toward lumen and their bases were resting on basement membrane. These acinar cells were purely mucous with flattened nuclei rested on basement membrane. The cytoplasm filled with mucinogen which stained light with H&E. These acini were positively reacted to PAS and AB showing several vacuoles inside acinar cells with basally located nuclei, these acini were negatively reacted to BPB showing clear cytoplasm. Serosa is the outer most portion of all these layers where it consisted of loose connective tissues with blood vessels, lymph vessels and nerves covered with simple squamous epithelium.