Dentine. Coloured scanning electron micrograph (SEM) of a section of healthy human dentine, a dense calcified tissue which forms the bulk of the body of a tooth. Dentine is similar to bone in composition, but is more highly mineralised & consequently much harder than bone. Dentine forms when the organic matrix secreted by cells called odontoblasts becomes calcified. It occurs between the enamel and the inner dental pulp and is permeated by a network of minute channels. These channels contain protoplasmic processes (coloured pink) of the odontoblasts. Dentine is highly sensitive to both touch & extremes of temperature. Magnification: x1,100 at 6x7cm size. x2,960 at 8x6ins,x1570 at 10x7cm master size.