Gross morphological features of the follicular pharyngeal tonsil of S. camelus. a: The pharyngeal tonsil on the left has been injected with Indian ink and sectioned to show the tonsillar crypts (yellow star). Dorsal surface of the pharyngeal fold (Pfd), adventitia of the proximal esophagus (Pe) and opening of the tonsil to the oropharynx (curved white arrow). b: View of the opening of the pharyngeal tonsil (T) as seen from the oropharynx. The pharyngeal fold (Pfv) forms its ventral border. Note the vertical vanes (V) and the intervening tonsillar crypts (yellow star) opening into a shallow tonsillar sinus. c: Cross-section of the tonsil injected with Indian ink. The ink has stained the lining of the crypts (yellow star) as well as the intervening connective tissue (arrow). The lymphoid tissue (Lt) appears a cream colour.