Detailed Study Notes on Spinal Ganglion Structure

Spinal Ganglion Structure and Function

  • This section focuses on the spinal ganglion stained with crystallophilus.

Overview of Spinal Ganglion

  • Identified as the same ganglion or slide section previously shown in earlier lectures.

  • Capsule:

    • The outer layer of the spinal ganglion.

    • Comprised of connective tissue that extends inwards as trabeculae; serves to support the ganglion.

  • Cortex:

    • The outer portion consisting primarily of the cell bodies of sensory neurons.

Inner Composition

  • The inner part of the ganglion consists of nerve fibers.

  • Presence of both longitudinal and cross-sectional views of nerve fibers (axons):

    • Indicates a polarized structure, allowing differentiation of areas within the ganglion.

Cell Bodies of Neurons

  • Shape and Appearance:

    • Cell bodies are circular in shape.

    • The circular shape arises from the absence of dendrites projecting from the cell bodies, unlike motor neurons.

  • Nucleolus:

    • Appears active when stained, characterized by a clear space around it indicating active chromatin.

    • This suggests that transcription is occurring within the cell body.

  • Cytoplasmic Features:

    • Presence of Nissl granules observed within the cytoplasm, which are crucial for protein synthesis.

Supporting Cells

  • Satellite Cells:

    • Nuclei of neuroglial cells identified as satellite cells (also referred to as oligodendrocytes).

    • It is noted that approximately 10 satellite cells surround each sensory neuron cell body.

Medulla Region Examination

  • Examination of the medulla region illustrates:

    • Cross sections of axons observed.

    • Each nerve fiber (axon) is surrounded by a halo, indicating where the myelin has dissolved.

    • The peripheral membrane is from Schwann cells that surround the axon.

  • A variety of axons can be identified:

    • Cross-sectional views as well as less identifiable longitudinal sections.

  • Supporting neuroglial cells are present, including satellite cells that provide further support for the axon.