Osteocyte lacunar size-lamellar thickness relationships in human secondaryosteons

Previous investigations carried out in our laboratory on secondary osteons have shown that osteocyte lacunae decrease in size from the cement line tow ards the Haversian canal, and lamellar bone is made up of alternating nonos teocytic dense lamellae and osteocytic loose lamellae, all having an interw oven texture of collagen fibers, Such alternation of acellular and cellular lamellae was hypothesized to depend on osteocyte recruitment from osteogen ic laminae in successive layers, assuming that the loose lamellae form beca use of alignment and fusion of the periosteocytic loosely arranged collagen fibers. In order to discover whether a correlation really exists between o steocyte lacunar size and lamellar thickness, as would be expected if the a bove-mentioned hypothesis were true, both these parameters were measured in completed secondary osteons in relation to their distance from the Haversi an canal. The size of osteocyte lacunae was measured under light microscopy on undecalcified dry-mounted ground section of tibial compact bone from th ree adult males and three adult females not affected by metabolic bone dise ase. The measurement of the thickness of bony lamellae was carried out on t he same samples under scanning electron microscopy, Statistical analyses of the results showed that the decrease in size of osteocytic lacunae from th e outer to the inner osteonal wall is paralleled by a decrease in thickness of osteocytic loose lamellae, The fact that acellular dense lamellae do no t follow such a decremental pattern, but remain of the same thickness throu ghout the osteonic wall, corroborates Marotti's view that the formation of lamellar bone depends on the orderly distribution of the osteocytes in alte rnating planes, The topographical distribution of osteocyte lacunar size an d lamellar thickness is briefly discussed in relation to secondary osteon m echanical function. (Bone 28:215-219; 2001) (C) 2001 by Elsevier Science In c. All rights reserved.