Calcification XXI. Detection of Nuclei of Crystallization in Rachitic Cartilage.

Abstract

Methods of differentiating rachitic tibial sections that do not contain nuclei of crystallization in the preosseous cartilage from those that have been exposed to the calcifying solution but are below the threshold of visibility of the silver stain test are presented. These exposed sections are regarded as "nucleated" because they exhibit properties similar to those where calcification is visible with the silver stain test. "Nucleated" sections calcified in vitro while the non-nucleated sections showed complete inhibition when subjected to the following: (a) incubation in a calcifying medium (Ca x P = 50) containing a mixture of iodoacetate and magnesium ions; (b) shaking in distilled water at room temperature for half an hour, followed by in vitro calcification at a Ca x P product of 50; and (c) heating in distilled water at 76-77[degree]C for 10 minutes, followed by in vitro calcification at a Ca x P product of 50. Calcification in vitro of "nucleated" sections took place at a lower Ca x P product than that needed for in vitro calcification of fresh, nuclei-free sections. It is suggested that the absence of nuclei should be established in studies of the nuclei-forming mechanism.