Related Experiment Video
Updated: Jun 4, 2026
Whole Animal Perfusion Fixation for Rodents
Published on: July 30, 2012
Perfusion of brain tissues with fixative
Abstract:
INTRODUCTIONIn many experiments it is necessary to section the brain to determine the location of a treatment (lesion or electrode) or to look at the histology of the brain using various staining techniques. Because the texture of the brain is so soft (often likened to soft cheese), it must be "fixed" before it can be removed from the skull. A fixative is a chemical that cross-links the molecules of the tissue, rendering it hard and preserving the tissue. This protocol describes a method for perfusing the brain with fixative (specifically, it describes how to perfuse a rat brain; slight modifications may be needed for different animals). A relatively simple gravity feed and the pumping mechanism of the heart is used to get fixative into the brain. A cannula is placed in the heart, or directly in the ascending aorta, of a deeply anesthetized animal. Blood is flushed out with saline first, and then with a fixative. The choice of fixative is often important if a specific staining technique is to be used, especially in immunocytochemistry, because the fixative can interfere with the staining sensitivity.
Insights
This protocol details a method for perfusing rat brains with fixative, a chemical that hardens tissue for histological analysis. Proper fixation is crucial for preserving brain structure and ensuring the success of subsequent staining techniques like immunocytochemistry.
Area of Science:
- Neuroscience
- Histology
- Experimental Biology
Background:
- Brain tissue is soft and requires fixation for histological examination and lesion/electrode localization.
- Fixatives are chemicals that cross-link tissue molecules, hardening and preserving the brain.
- The choice of fixative can impact the sensitivity of staining techniques, particularly immunocytochemistry.
Purpose of the Study:
- To describe a method for perfusing rat brains with fixative.
- To outline a technique utilizing gravity feed and cardiac pumping for fixative delivery.
- To provide guidance on preparing brain tissue for histological analysis.
Main Methods:
- Anesthetize the animal deeply.
- Insert a cannula into the heart or ascending aorta.
- Flush blood with saline, followed by perfusion with a fixative solution.
Main Results:
- Successfully delivered fixative throughout the brain via cardiac perfusion.
- Hardened brain tissue suitable for sectioning and histological analysis.
- Demonstrated a method applicable to rat brains with potential for other species.
Conclusions:
- The described perfusion method effectively prepares brain tissue for histological examination.
- This technique is essential for experiments requiring precise localization and detailed tissue analysis.
- Understanding fixative properties is critical for optimizing downstream staining protocols.
