Fig. 9
Harriotta raleighana (Rhinochimeridae; Holocephali; Chondrichthyes). Progressive mineralization of ovoid tissue with BSE ultrastructure lowest to highest magnification. A hypermineralized, featureless dentine filling ovoid at worn oral surface (ov, w.os), surface loss of sclerotic dentine (sod), compared to e, representing one of the least mineralized ovoid. b mineralization beginning in centre of ovoid, B and E are more aboral compared to A, field of C shown. c, d showing the more linear arrangement of the mineral alongside the tubule walls in the centre of the ovoid (asterisk), with tiny empty tubule lumen, the mineralized periphery of the ovoid is slightly less dense dentine, field of D shown. d mineralization shown as crossing crystal bundles, reflecting original chaotic mix of the dentine tubules, individual crystals are not resolved. e barely mineralized ovoid, within narrow mineralized trabecular dentine capsule (td), central region of open tubules as shown in F. f closeup of tubules (tu) with open saccules (sac), field of G shown. g matrix of ovoid filled with complex network of dentine tubules (tu), with enlarged, widened tubules, saccules, (sac), tiny open tubules, vesicles, and empty spaces, some have small mineral granules (gr) within. h slightly lower magnification than G of forming ovoid region, but in transmitted light with Nomarsky optics, to show the same chaotic collection of fine membrane vesicles, thicker saccules, some optically dense material in them (disorganized mineral) and background faint linear structure. Scale bars A, B, E = 100 μm; C, F = 30 μm; D, G = 10 μm; H = 50 μm