<prompt> Number of tubules per unit areaIs 2 times more at pulpal endIs 3 times more at pulpal endIs 4 times more at pulpal endIs 5 times more at pulpal end  <response>: The number of tubules per unit area is more at the pulpal end by 4 times than at their terminal end. Hence the intertubular dentin is well appreciated at the terminal end. The tubules generally have a doubly convex course, the primary curvature often called S shaped tubules, the first convexity of which is directed towards apex. 