Presentation (Project) Title

3D Reconstruction of a Developing Astrocyte in the Medial Nucleus of the Trapezoid Body from Volume Electron Microscopy

Mentor Information

George Spirou (Department of Medical Engineering)

Presentation Format

Event

Abstract

The medial nucleus of the trapezoid body (MNTB) is an excellent model system for studying neural circuit development due to the rapid maturation of a highly homogenous neuronal population that is monoinnervated by the largest terminal in the mammalian brain, the calyx of Held (CH). Glial cells were once thought to be the glue of the brain. However, recent evidence has demonstrated that glia have a more active role in neural circuit development. One of the four main classifications of glial cells, astrocytes, are the most abundant glial cell type in the CNS with distinct morphologies that underlie differing functional roles. Numerous studies have examined the relationship between astrocyte diversity and functionality across various brain regions, as well as within the same region; however, the exact role of astrocytic heterogeneity remains elusive, particularly during development. To visualize the morphological features of astrocytes at an ultrastructural level during CH development, we utilized our unique developmental series of serial block-face scanning electron microscopy (SBEM) volumes. We have completed a partially reconstructed postnatal day 6 astrocyte to observe and analyze complex astrocytic morphologies. Initial analysis reveals the preservation of characteristic astrocytic features, such as formation of end feet and vellus processes. We also observed several novel characteristic features, such as large mitochondrial width, prevalent stacks of endoplasmic reticulum, and axonal ensheathment. This study highlights the complex morphology of astrocytes and their diverse heterogeneity by identifying novel ultrastructure morphological features during a critical period of synaptic development and neural circuit formation in the MNTB.

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3D Reconstruction of a Developing Astrocyte in the Medial Nucleus of the Trapezoid Body from Volume Electron Microscopy

The medial nucleus of the trapezoid body (MNTB) is an excellent model system for studying neural circuit development due to the rapid maturation of a highly homogenous neuronal population that is monoinnervated by the largest terminal in the mammalian brain, the calyx of Held (CH). Glial cells were once thought to be the glue of the brain. However, recent evidence has demonstrated that glia have a more active role in neural circuit development. One of the four main classifications of glial cells, astrocytes, are the most abundant glial cell type in the CNS with distinct morphologies that underlie differing functional roles. Numerous studies have examined the relationship between astrocyte diversity and functionality across various brain regions, as well as within the same region; however, the exact role of astrocytic heterogeneity remains elusive, particularly during development. To visualize the morphological features of astrocytes at an ultrastructural level during CH development, we utilized our unique developmental series of serial block-face scanning electron microscopy (SBEM) volumes. We have completed a partially reconstructed postnatal day 6 astrocyte to observe and analyze complex astrocytic morphologies. Initial analysis reveals the preservation of characteristic astrocytic features, such as formation of end feet and vellus processes. We also observed several novel characteristic features, such as large mitochondrial width, prevalent stacks of endoplasmic reticulum, and axonal ensheathment. This study highlights the complex morphology of astrocytes and their diverse heterogeneity by identifying novel ultrastructure morphological features during a critical period of synaptic development and neural circuit formation in the MNTB.