Larynx-Associated Lymphoid Tissue (LALT) in Young Yak (Bos grunniens)

Abstract

The distribution of lymphoid tissue in the mucosa of the yak larynx was observed. A total of 10 yak larynges were examined both macroscopically after tissue fixation in acetic acid and microscopically using histology. It was found that no paraepiglottic tonsil was present in yak, although a few lymphoid follicles with immunopositive reactions for follicular dendritic cells were present in the mucosa at the base of the epiglottis and the corniculate processes of the arytenoid cartilages. Organized lymphoid tissue was identified in the mucosa of vestibulum laryngis and cavum infraglotticum. The results suggest that larynx-associated lymphoid tissue is a ubiquitous finding in yak. Although the yak larynx is devoid of a proper tonsil, it can probably still organize a local immune response due to the presence of LALT.