Figure 3. Histological sections of North Island brown kiwi (Apteryx mantelli) and bar-tailed godwit (Limosa lapponica) bill-tips.

A: Diagram of three coronal sections through a North Island brown kiwi bill, taken at: (1) 9 mm from the tip of the upper bill rhamphotheca (showing upper bill above, lower bill beneath); (2) 6 mm from tip of the upper bill rhamphotheca , sectioned through the sensory pad area forward of the tip of the rhamphotheca of the lower bill); (3) 3 mm from the tip of the upper bill rhamphotheca. Black areas represent the premaxilla and dentary bones. Dark grey shaded areas represent cross sections through the major nerves. Areas of soft tissue are shaded pale grey, the keratin and major blood vessels are left white. Herbst corpuscles (in 3) are white, with a central black line to represent the nerve axon. Bold lines indicate the outer surface of the keratin layer, finer lines indicate the junction between the dermal and keratin layers and the outlines of major blood vessels, nerves, and Herbst corpuscles. In (1), the premaxilla is perforated by the two nasal passages, bordered with bold lines and colored white. B: Sagittal section through a sensory pit in the North Island brown kiwi premaxilla, stained with Masson’s trichrome and C: a sensory pit in the bar-tailed godwit dentary, stained with haematoxylin and eosin. Abbreviations: N: nerves, B: bone. Examples of Herbst corpuscles are highlighted with white arrows. Scale bars = 100 µm.