Comparative study of bone micro-architecture of some mammalian bones

In the present study, a comparison has been made on the size of osteon and Haversian canal from bone specimen of seven mammalian species [rat, rabbit, cat, dog, monkey, adult man and cow] with two extinct specimens from primitive land animals (Diadectes and Iguanodon). Furthermore, relationship between size or weight of animal with respect to the size of its osteon and Haversian canal has been explored by applying allometric scaling laws to the micro architecture data. The results indicate that in general, osteon and Haversian canal size increases with increasing body weight however, the relative size of the osteon and Haversian canal decreases per unit body weight i.e. rat osteons are larger relative to human and dinosaurian osteon. Interestingly, the ratio of osteon to Haversian canal diameters were in the range of 4 to 6 for all the animals (excluding rat) investigated in the present study including the dinosaurs. This suggests firstly, a close resemblance of extinct bone micro-architecture to mammals and secondly that osteon and Haversian canal sizes were optimised for efficient transport of nutrients and metabolites from the animal body to the bone cells. It may be explained by the concept that outside the optimum range an increase in osteon diameter actually reduces the efficiency of transportation of nutrients and waste products