Effects of Fixation Delay and Colchicine on the Presence of Stippled Material in the Newly Formed Enamel of the Rat Incisor.

Normal and colchlclne-injected rats were perfusion-fixed at 0 to 20 min after washing out the blood. Secretory ameloblasts and underlying enamel were examined ultrastructurally. In the normal rats, there was practically no accumulation of stippled material when the perfusion fixation was started immediately after washing out the blood. Various amounts of stippled material accumulated along the plasma membrane of Tomes' process and between the rod and interred enamel when the perfusion fixation was delayed. However, the ultrastructure of ameloblasts was still well preserved. Following colchicine injection, the amount of stippled material decreased greatly. From these results, it is suggested that accumulation of a large amount of stippled material is an artifact of fixation. However, it is also suggested that the secretory activity of the ameloblast plays an important role in the formation of stippled material [ABSTRACT FROM PUBLISHER]