**9. Lymphoid tissue of oral cavity of goat**

Lymphoid tissue comprises mainly of lymphocytes within the oral cavity and is responsible for maintaining immunity. Such tissues are arranged in diffused and nodular form also called as lymphoid patches. There are two types of lymphoid organs, the primary lymphoid organs comprise of bone marrow and thymus where the development and schooling of the lymphocytes occurs, and secondary lymphoid organs include spleen, lymph nodes, and associated tissues of skin, mucosa, gut, and bronchi,. where the mature naive T and B lymphocytes identify the antigen where they get activated, proliferated and differentiated into effectors and memory types. The tonsils comprise of lymphoid cells (diffuse and nodular), including lingual and palatine, lined by keratinized stratified squamous epithelium [48]. On the other hand, para-epiglottic, pharyngeal, and tubal mucosae are lined by pseudostratified columnar ciliated epithelium on major areas contributing largely to immunity [51].
