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

Figure 5

Anatomical localization and histological characteristics of the equine tonsils. (a) Median section through an equine head. The upper left insert shows the pharyngeal and tubal tonsils that are only visible after 4 h fixation in 2% acetic acid. The encircled area in this insert represents the area of the pharyngeal tonsil. Caudoventral to the slit-like opening of the auditory tube (white arrows), numerous white nodules belonging the tubal tonsil (black arrows) can be observed (R: rostral, C: caudal, GP: guttural pouch). The tonsil of the soft palate at the oropharyngeal side of the soft palate (small encircled area), the lingual tonsil (boxed area), and the palatine tonsil (larger encircled area, detail shown in the lower left insert) are additionally illustrated. (b) Histological section through the lingual tonsil. (c–f) Histological sections through parts of the palatine (c), pharyngeal (d), and tubal (e) tonsils and the tonsil of the soft palate (f), respectively. Primary lymphoid follicles belonging to the tubal tonsil are indicated by arrows. Tonsillar follicles are encircled in (b) and (c).