High resolution scanning electron microscopy of frog sartorius muscle

Area of Science:

• Cell Biology
• Microscopy
• Muscle Physiology

Background:

• Understanding muscle ultrastructure is key to comprehending muscle function.
• Scanning electron microscopy (SEM) offers potential for detailed 3D visualization.

Purpose of the Study:

• To investigate the three-dimensional ultrastructure of frog sartorius muscles using field emission-type SEM.
• To evaluate various specimen preparation techniques for high-resolution SEM imaging of muscle tissues.

Main Methods:

• Utilized a field emission-type scanning electron microscope (SEM).
• Tested diverse preparative procedures, including fixation with tannic acid-OsO4 and critical point drying.
• Employed freeze-fracturing techniques for examining the sarcolemma.

Main Results:

• Optimal visualization of muscle fiber surface and intracellular organization achieved with tannic acid-OsO4 fixation and critical point drying.
• The basal lamina appeared as a felt-like layer with adhering filaments.
• The inner sarcolemma surface showed caveolae and attached filaments; freeze-fracturing revealed caveolae and T-system tubules.
• Myofibrils displayed characteristic sarcomere patterns, with regularly beaded thick myofilaments.

Conclusions:

• High-resolution SEM is valuable for studying cell and tissue ultrastructure, but limitations exist.
• Specific preparation methods enhance visualization of different cellular components.
• The study provides detailed insights into frog sartorius muscle ultrastructure.