Whole Central and Peripheral Nervous System Mice Dissection

Summary

Here, we present a protocol to complete the dissection of central and peripheral nervous systems of mice. The dissected tissues are further analyzed in downstream applications, such as taking gross pictures or histology.

Abstract

Animal models represent the workhorse of the neuroscience field. Despite this, today, there is still no step-by-step protocol to dissect a complete rodent nervous system, nor is there a complete schematic representing it that is freely available. Only methods to harvest the brain, the spinal cord, a specific dorsal root ganglion, and the sciatic nerve (separately) are available. Here, we provide detailed pictures and a schematic of the central and peripheral murine nervous system. More importantly, we outline a robust procedure to perform its dissection. The 30 min pre-dissection step allows isolating the intact nervous system within the vertebra with muscles free of viscera and skin. A 2-4 h dissection follows it under a micro-dissection microscope to expose the spinal cord and the thoracic nerves, and finally peel the whole central and peripheral nervous system off the carcass. This protocol represents a significant step forward in studying the anatomy and pathophysiology of the nervous system globally. For example, the dissected dorsal root ganglions from a neurofibromatosis type I mice model can be further processed for histology to unravel changes in tumor progression.

Introduction

The overall goal of this method is to isolate a mouse's central and peripheral nervous system in one piece. There is currently no protocol to dissect the whole nervous system of a rodent to study it on a global level. Neuroscientists typically use the sciatic nerve as a surrogate for any peripheral nerve¹, and the L3 to L5 ganglions² as a surrogate for any ganglions. Using these methods, it is impossible to conclude if the results are specific to the particular nerve/ganglion. As it is known that at least some nerve pathologies do not affect all nerves and ganglions equally^3,

Protocol

The protocols used in this study have been approved by the Comité Institutionnel des Animaux de l'Université de Sherbrooke, a Canadian Council on animal care certified institution.

1. Preparation for micro-dissection (pre-dissection)

1. Perform anesthesia with 5% isoflurane, followed by euthanasia with 2% isoflurane and 10 psi of CO₂ until there are no vital signs.
   NOTE: Do not perform cervical dislocation, as this damages the spinal cord and cervical ganglions.
2. Place the euthanized mouse facing up (anterior view) on a dissection pad, and spray the fur with 70% ethanol.

Results

Rodents have been instrumental to our understanding of nervous system biology and pathophysiology¹⁰. Intriguingly, no methods present the complete dissection of a rodent's central and peripheral nervous system to asses the anatomy and pathological variation in a real-time model^1,2,11. Figure 1 presents an overview of step 1 to step 4 (the preparation for the micro-dissection,.......

Discussion

To prevent the muscles and nerves from drying out, the carcass should be soaked in PBS every 10 min. When dislocating the lower limbs (step 1.12.6), it is important to always have the sciatic nerve plexus and L2 in sight to avoid damaging/tearing it. When dissecting the brain (step 1.14.4), it is critical to avoid going too deep so as not to damage the brain. When dissecting the dorsal root ganglions and peripheral nerves in general, it is critical to use high-quality (not damaged) Dumont mini-forceps to avoid damaging t.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Dumont mini-forceps	Fine Science Tools	#11200-10
Extra Bonn scissors	Fine Science Tools	#14084-08
Formalin 10%	Fischer Scientific	#22-046-361
PBS 1x	BioShopCanada	#PBS404.500
Standard anatomical forceps	Fine Science Tools	#91100-12
Surgical scissors	Fine Science Tools	#140001-12
Vannas spring scissors	Kent Scientific	#INS600124