Figure 3.

Gross morphological features of the follicular pharyngeal tonsil of D. novaehollandiae. a-c: The pharyngeal tonsil (T) (black dotted outline) is shown sectioned through the planes a-c as indicated in Figure 3e. Note the positioning of the tonsil between the caudo-lateral extension (white star) and the ventral surface of the pharyngeal fold (Pfv). The tonsil displays a central crypt (black arrow) from which numerous smaller crypts branch (blue dotted outline). d: The recess (R) enclosed by the dorsal surface of the pharyngeal folds (Pfd) with the attached caudo-lateral extension (white star) and the proximal esophagus (Pe). Ventral surface of the pharyngeal folds (Pfv) and opening of the tonsil into the oropharynx (white arrow). e: Dorsal surface of the pharyngeal fold (Pfd) with the caudo-lateral extension (white star) and attached proximal esophagus (Pe). Black dotted lines (a-c) indicate the plane of sectioning corresponding to Figures 1a-c. Bar = 4 mm.