Figure 2
Structural basis and spatial organization of spine-associated bioluminescent display.
(a) Frontal edge of the second dorsal fin in transversal section (TS; 7 μm) showing the position of SAP rows (red arrows). ce, ceratotrichia; pl, pigmented layer. (b) Close-up of a SAP (TS; 7 μm) showing the position of photogenic cells (photocytes; white arrows). le, lens; ps, pigmented sheath. (c) Same SAP (TS; 7 μm) showing the autofluorescence of the photocyte vesicles (red arrows) under U.V. application. (d) Micro-CT of first and second dorsal finspines. Top inserts are transversal sections situated close to the tip and the base. Note how the spine cross-section in 2d have been rotated 90° anticlockwise relative to the cross-section at the top of the figure. Scale bars correspond to 500 μm in (a), (d) and to 150 μm in (b), (c). (e) Spectral transmittance of the spine (grey line) with a superimposed Gaussian spectrum (dashed line) of shark luminescence14. The spine can hypothetically transmit ~ 10% of SAP luminescence frontally.
