Mineralization of invertebrate cartilage.

Although invertebrate cartilage tissues do not mineralize in nature, it is now reported for the first time that when excised gill cartilage tissue from Limulus (horse shoe crab) is placed in an appropriate incubation medium metastable to hydroxyapatite, mineralization will occur. The mineralization is temperature dependent, and takes place at 37 degrees but not at 20 degrees. Incubations in media metastable to calcite have not produced mineralization. Histologic examination of mineralized tissues showed mineral deposits predominantly within cells, and to a lesser extent in the matrix. X-ray diffraction of the deposited mineral revealed a typical biological hydroxyapatite pattern.