Which of the following calcified tissues have minimum lag phase between matrix formation and mineralization?

  # Which of the following calcified tissues have minimum lag phase between matrix formation and mineralization?

A. Enamel

B. Cementum

C. Bone 

D. Dentin

The correct answer is A. Enamel.

The formation of the enamel can be described as the secretory phase (primary mineralization or matrix formation) where only 30 percent is mineralized and the secondary phase or maturation characterized by the crystal growth and complete mineralization. There is no time lag between these phases and hence the mineralization of enamel is a continuous process. This is the reason why structure equivalent to that of predentin or osteoid as seen in dentin and bone is not found in enamel. 

The way mineral is introduced into the organic matrix of enamel differs from its introduction in other hard tissues. In these tissues matrix vesicles provide a closed environment to initiate crystal formation in a preformed organic matrix. No matrix vesicles are found in association with the initial mineralization of enamel protein.