Lamellar bone tissue

Transverse section of tubular bone diaphysis

(Schmorl’s stain)

A bone as an organ comprises not only lamellar bone tissue but also periosteum and endosteum as well as some soft tissues (bone marrow, blood vessels, and nerves).

Lamellar bone tissue constitutes both spongy and compact bones.

Spongy bone makes up the internal parts of diaphyses:

• the bone is organized as a system of bone trabeculae #1, #2. Between them, there are intertrabecular spaces #1, #2 with bone marrow and blood vessels;
• spongy bone trabeculae consist of parallel trabecular plates and rods #1, #2. There are osteocyte cell bodies in lacunae #1, #2 between them (while osteocytic processes are found in bone canaliculi inside the plates and rods);
• most trabeculae have no blood vessels. Bone nutrition is due to diffusion from soft tissue vessels of intertrabecular spaces.

Compact bone forms cortical portions of diaphyses. Its bone lamellae constitute a very dense system, and there is little soft tissue, so the mechanical strength of such a bone is high.

Compact bone includes:

• periosteum #1, #2 that covers bones from the outside (after acid decalcification of a bone, the bone structure may lose some details). The outermost layer of the periosteum is formed by dense connective tissue proper, whose fibers interlace with ligaments and muscles at the sites of their junction. The deep (innermost) layer of the periosteum is actually loose connective tissue proper with osteogenic cells;
• layer of external circumferential lamellae;
• layer of internal circumferential lamellae (at the boundary with medullary cavity of diaphysis);
• layer of osteons forming the principal part of compact bones in lamellar bone tissue. The layer consists of osteons of a cylindrical shape (depending on the direction, there are longitudinal and transverse sections of them).

The transverse section shows that an osteon is a system of bone lamellae #1, #2, #3 (up to 25), arranged concentrically around the osteon canal:

• this Haversian canal is lined by osteogenic cells of the periosteum; it contains a nutrient blood vessel;
• bone lamellae alternate with lacunae #1, #2 (bone cavities where osteocytic cell bodies are found);
• osteocytic processes enter numerous bone canaliculi that permeate the lamellae in perpendicular directions.

The spaces between osteons are filled by interstitial lamellae, which are remnants of aged osteons.