PRACTICAL WORKSHOP ON HISTOLOGY, CYTOLOGY AND EMBRYOLOGY - 2016

Chapter 4. TISSUES

Slide 52. Development of bone in place of cartilage.

Staining: hematoxylin and eosin.

Magnification: x80.

With the naked eye, the specimen reveals the outlines of a future long tubular bone: its extremities — the epiphyses, and its shaft — the diaphysis.

We examine the object starting from the diaphysis. In the central part of the diaphysis, The process of perichondral ossification takes place, resulting in The formation of a perichondral bone collar (1). It appears as an elongated pinkish area along the diaphysis, interspersed with the purple nuclei of osteoblasts and osteocytes. In the areas where Cartilage is preserved, chondrocytes are visible against a blue Background. Between them lie cartilage resorption cavities (2), the fusion of which subsequently forms the Bone Marrow cavity.

In the metaphysis (the transition zone from the diaphysis to the epiphysis), the area closest to the diaphysis is the zone of cartilage resorption and immature Bone tissue formation (3). Further on, we distinguish the zone of vesicular Cells (4) and the zone of columnar cartilage (5). In the latter, chondrocytes proliferate and arrange themselves in columns (responsible for the longitudinal growth of the bone). Closest to the epiphysis is the zone of unchanged cartilage (6).

The epiphysis contains hyaline cartilage of typical Structure. When Blood Vessels grow into it, the epiphyseal ossification center — enchondral bone — is formed.

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Slide 52. Development of bone in place of cartilage.