Histomorphometric Characterization of Forestomach of Yak ( Bos grunniens) in the Qinghai-Tibetan Plateau Caracterización Histomorfométrica del Preestómago del Yak (Bos grunniens) en la Meseta Qinghai-Tíbet

ANG, J.; LI, H.; ZHANG, L.; ZHANG, W Y.; YUE, M.; SHAO, B. & ANG, J.W Histomorphometric Characterization of Forestomachof Yak (Bos grunniens) in the Qinghai-Tibetan Plateau. Int. J. Morphol., 32(3):871-881, 2014. SUMMARY: Six forestomachs of yaks ( Bos grunniens) were studied with gross dissection and histological methods. It was foundthat the forestomach of yak consisted of the following three parts, rumen, reticulum and omasum, which were composed of the muc osa,submucosa, muscularis and serosa. In addition, the mucosal epithelium was covered with stratified squamous epithelium, with part ofkeratinized the shallow cells. Rumen, the mucosa of which formed ligulate papillae varying in size and shape, was no muscularismucosa. Reticulum, consisted of a surface epithelium that invaginated to various extent into the lamina propria, formed various folds inshape, namely, grid-like small rooms. Furthermore, there are many secondary folds densely covered with keratinized papillae. Th e moststriking feature of the omasum was to be formed the laminae omasi varying in length, with short and rough papillae distributing on bothsides. Taken together, there was no glands within the mucosa and lamina propria of forestomach of yak, where diffuse lymphoid t issuescan be observed clearly. It is, therefore, believed that the yak forestomach may have evolved those specific structural characteristics inresponse to the unique living environment and dietary habits impose on the Qinghai-Tibetan Plateau.KEY WORDS: Bos grunniens; Forestomach; Histomorphometric; Qinghai-Tibetan Plateau.