THE ARRANGEMENT OF HAVERSIAN SYSTEMS IN A DIAPHYSIS – 4
The top figure shows a detail of a cross sectioned diaphysis.
The bone surface is at the bottom of the figure. Observe that it is formed by a stack of slightly curved parallel bone lamellae that surround completely the bone diaphysis. They constitute the external or outer circumferential system that delimit the outer surface of the bone.
The cavities occupied by osteocytes called lacunae are seen as small dark structures (some of them indicated by arrows).
A similar system, located at the inner surface of the diaphysis, constitutes the internal or inner circumferential system (not shown in this figure).
The bottom figure shows groups of short parallel bone lamellae the intermediate or interstitial lamellae. There are millions of small groups like these in the diaphysis. The places occupied by osteocytes are seen as small dark structures (some of them indicated by arrows).
The intermediate lamellae fill the spaces between the cylinders of concentric lamellae that form the Haversian systems.
There are in the image two Haversian systems or osteons and part of a third. They are seen cross-sectioned and marked with the letter H. Each Haversian system has a central canal called the Haversian canal.
Diaphysis (in cross section). Schmorl’s technique. Magnification: medium.
Diaphysis (in cross section). Schmorl’s technique. Magnification: medium.