High resolution scanning electron microscopy of elastic cartilage

Area of Science:

• Biochemistry
• Cell Biology
• Histology

Background:

• Elastic cartilage, such as the rat epiglottis, plays a crucial role in structural support.
• Understanding the ultrastructure of cartilage matrix is essential for comprehending its biomechanical properties.

Purpose of the Study:

• To investigate the ultrastructure of elastic cartilage in the rat epiglottis using high-resolution scanning electron microscopy (SEM).
• To identify and characterize the fibrils and associated structures within the cartilage matrix.

Main Methods:

• High-resolution scanning electron microscopy (SEM) was employed to examine the elastic cartilage of the rat epiglottis.
• Detailed imaging was performed to visualize chondrocytes, lacunae, and the surrounding extracellular matrix.

Main Results:

• Chondrocytes were observed to be anchored by fibrils originating from the territorial matrix.
• The territorial matrix showed a dense, tangential fibril network around lacunae, while the inter-territorial matrix formed a 3D network of interconnected sheets.
• A novel fibril substructure, featuring circumferential protuberances (ridges 12-19 nm apart), was visualized for the first time, suggesting collagen fibrils with attached proteoglycans.
• Matrix granules were also observed attached to the fibrils.

Conclusions:

• The study elucidates the fibrillar organization and substructure of rat epiglottis elastic cartilage.
• The findings suggest that the observed fibrils are collagen, decorated with proteoglycans and matrix granules.
• The inability to visualize elastin using high-resolution SEM presents a puzzling observation requiring further investigation.