The Tonsils Revisited: Review of the Anatomical Localization and Histological Characteristics of the Tonsils of Domestic and Laboratory Animals

Figure 1

Anatomical localization and histological characteristics of the ovine tonsils. (a) Median section through an ovine head showing the location of the lingual tonsil (1), the palatine tonsil (2) of which a larger magnification is shown in the lower left insert, the paraepiglottic tonsil (3) that is located at the lateral basis of the epiglottis (lower right insert), the tonsil of the soft palate (4) consisting of scattered lymphoid nodules at the nasopharyngeal side of the soft palate (higher magnification after 2% acetic acid fixation for 4 h shown in the upper right insert), the pharyngeal tonsil (5) of which a larger magnification is presented in the upper left insert, and the tubal tonsil (6) consisting of scattered lymphoid nodules located caudoventral to the opening of the auditory tube (higher magnification after 2% acetic acid fixation for 4 h also shown in the upper right insert). (b) Histological section through the paraepiglottic tonsil. (c) Histological images of the lingual tonsil. The upper view shows aggregations of lymphoid cells (arrows) in between the lingual muscles and salivary glands. The lower image demonstrates the presence of an aggregation of lymphoid cells in the connective tissue core of a vallate papilla. (d–g) Histological sections through the palatine (d) and tubal (e) tonsils, the tonsil of the soft palate (f), and the pharyngeal tonsil (g), respectively. A tonsillar follicle is encircled in (d); the lymphoid tissue in (e) and (f) is indicated by the arrows.