Ultrastructure of astrocytes using volume electron microscopy: A scoping review

Area of Science:

• Neuroscience
• Structural Biology
• Computational Neuroscience

Background:

• Astrocyte morphology is vital for brain homeostasis, synaptic activity, and structural support.
• Quantifying fine astrocytic morphologies is challenging due to their nanoscale dimensions.
• Electron microscopy (EM) is essential for visualizing these intricate structures.

Purpose of the Study:

• To provide a comprehensive overview of the current state of astrocyte ultrastructural analysis.
• To categorize existing research based on methodology, animal models, and brain regions.
• To synthesize data on key morphological features like volume, surface area, and synaptic ensheathment.

Main Methods:

• Conducted a scoping review of 439 articles identified via a Pubmed search.
• Included 45 non-duplicated articles focusing on astrocyte ultrastructural analysis.
• Categorized studies by research focus, animal models, brain region, volume EM (vEM) techniques, and segmentation methods.

Main Results:

• Identified and summarized various volume EM (vEM) techniques (e.g., serial block-face, focused ion beam scanning EM).
• Detailed new astrocytic morphological features revealed through extensive 3-D model analyses.
• Compiled quantitative data on astrocyte volume, surface area, branching complexity, and synaptic ensheathment from the literature.

Conclusions:

• Volume EM techniques enable high-resolution imaging and detailed 3-D analysis of astrocytic processes.
• This review serves as a valuable resource for researchers in structural biology and computational neuroscience.
• The synthesized data facilitates a deeper understanding of astrocyte morphology and its functional implications.