Yolanda is asked to review a bone slide that her professor has set up under the microscope. She sees concentric layers surrounding a central cavity. Is this bone section taken from the diaphysis or the epiphyseal plate of the specimen?

Verified step by step guidance

1. Step 1: Understand the structure described. Concentric layers surrounding a central cavity are characteristic of an osteon or Haversian system, which is the fundamental functional unit of compact bone.
2. Step 2: Recall the locations of bone structures. The diaphysis is the shaft of a long bone and is primarily composed of compact bone containing osteons, while the epiphyseal plate is a region of hyaline cartilage involved in bone growth and does not contain osteons.
3. Step 3: Identify the tissue type based on the microscopic features. Since concentric lamellae (layers) around a central canal are features of compact bone, this indicates the section is from compact bone tissue.
4. Step 4: Connect the tissue type to the bone region. Compact bone with osteons is found mainly in the diaphysis, whereas the epiphyseal plate consists of cartilage and lacks osteons.
5. Step 5: Conclude that the bone section with concentric layers around a central cavity is from the diaphysis, not the epiphyseal plate.

Key Concepts

Bone Microstructure - Osteon

An osteon is the fundamental functional unit of compact bone, characterized by concentric lamellae (layers) surrounding a central canal (Haversian canal) that contains blood vessels and nerves. Recognizing osteons helps identify compact bone tissue under the microscope.

Diaphysis vs. Epiphyseal Plate

The diaphysis is the shaft of a long bone composed mainly of compact bone with osteons, while the epiphyseal plate is a region of hyaline cartilage found at the ends of long bones where growth occurs. The epiphyseal plate lacks the concentric lamellar structure seen in osteons.

Histological Differences Between Bone Regions

Compact bone in the diaphysis shows organized osteons with concentric layers, whereas the epiphyseal plate consists of cartilage cells arranged in zones of proliferation and hypertrophy without concentric lamellae. Identifying these differences aids in determining the bone section's origin.