title: X-ray diffraction of the calcified tissues in Polypterus.
abstract: Pyrolyzed scales, fin spines, and bone from the ray-finned bony fish Polypterus (Actinopterygii) showed two mineral phases on X-ray diffraction: hydroxyapatite (HA), Ca5(PO4)3OH, and whitlockite, Ca3(PO4)2. The ratio of HA/whitlockite varied with the structure (scale, spine, bone) within each individual fish. The relative proportions of HA to whitlockite in pyrolyzed samples reflected the Ca/P ratio of the sample. Whitlockite appears after pyrolysis when the Ca/P is lower than 1.67. Among the five fish investigated, for each structure a general trend was noted. The proportion of HA relative to whitlockite increased with size (age) of the fish. Thus the smallest fish, a juvenile, exhibited a low Ca/P mineral in its calcified tissues, whereas the larger fish had progressively more HA and less whitlockite.
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000032:analysis*; D002130:Calcium Phosphates / Q000032:analysis; D005260:Female; D005399:Fishes; D006882:Hydroxyapatites / Q000032:analysis; D008297:Male; D014961:X-Ray Diffraction
chemical_list: D002130:Calcium Phosphates; D006882:Hydroxyapatites