Scanning electron microscopy of echinoid podia

Area of Science:

• Marine Biology
• Echinoderm Anatomy
• Scanning Electron Microscopy

Background:

• Sea urchin tube feet are crucial for locomotion and sensory functions.
• Previous studies utilized transmission electron microscopy for structural analysis.
• Detailed ultrastructural insights into tube foot components remain valuable.

Purpose of the Study:

• To elucidate the fine structure of Strongylocentrotus franciscanus tube feet using scanning electron microscopy (SEM).
• To provide detailed visualization of the layered tube-foot wall components.
• To compare SEM findings with existing transmission electron microscopy data.

Main Methods:

• Fractured preparations of Strongylocentrotus franciscanus tube feet were examined.
• Scanning electron microscopy (SEM) was employed for high-resolution imaging.
• Detailed analysis of epithelial layers, nerve plexus, basal lamina, and connective tissue.

Main Results:

• The outer epithelium exhibits ciliated tufts, potentially associated with sensory cells.
• The nerve plexus consists of bundles of varicose axons.
• The basal lamina is a mechanically resistant and elastic membrane.
• The luminal epithelium (coelothelium) comprises flagellated collar cells.
• Muscle fibers did not show innervation from the basi-epithelial nerve plexus.

Conclusions:

• SEM provides complementary high-resolution data on sea urchin tube foot ultrastructure.
• The study confirms and expands upon previous transmission electron microscopy findings.
• Specific details of outer and inner epithelia were clarified, including potential sensory cilia and collar cells.