Identification of challenged subarachnoid free cells

Area of Science:

• Neuroscience
• Immunology
• Cell Biology

Background:

• The leptomeninges are crucial membranes protecting the central nervous system.
• Intrathecal injections are used to deliver substances directly into the cerebrospinal fluid.
• Bacillus Calmette-Guerin (BCG) is an immunotherapy agent with potential inflammatory effects.

Purpose of the Study:

• To characterize the surface morphology of free cells within the leptomeningeal sheaths.
• To identify distinct cell types based on their external features using electron microscopy.
• To investigate cellular responses following intrathecal BCG administration.

Main Methods:

• Scanning Electron Microscopy (SEM) was employed to visualize cell surface structures.
• Transmission Electron Microscopy (TEM) was used to examine internal cell composition.
• Dogs received an intrathecal injection of BCG, and samples were collected twelve days post-injection.

Main Results:

• Three distinct free cell types were identified on the leptomeningeal sheaths.
• Macrophages showed abundant plasmalemnal blebs, appearing as large membrane-bound vacuoles via TEM.
• Lymphoblasts presented smooth surfaces with basal microvilli indenting underlying pial cells, while neutrophils had numerous microvilli, resembling chrysanthemum flowers.

Conclusions:

• The observed external features suggest distinct surface topographies for macrophages, lymphoblasts, and neutrophils in the leptomeningeal environment.
• These characteristic surface morphologies may aid in identifying cell types and understanding their interactions within the meninges.
• The study highlights the utility of SEM in discerning cellular heterogeneity in response to intrathecal challenges.