Carnoy's fixative solution is widely used in both plant and animal histology. It is an acidic fixative recommended for preserving nucleic acids (nucleus, chromatin, Nissl bodies) and glycogen. It is also useful to fix fibrous proteins. Carnoy's fixative performs a very fast fixation, and it is therefore used to shorten the fixation time. It can be done in about 1 h of fixation, depending on the sample size. In addition, the fixation process is also a dehydration process, since it is an alcoholic solution. Thus, after fixation, samples can be immersed in absolute alcohol and do the embedding afterwards.
Almost all alcoholic fixatives may render tissue retractions and lysis of some cell organelles, such as mitochondria, or erythrocytes, and dissolves lipids. In the Carnoy's fixative, acetic acid and chloroform partially counteract the retractions. The ability to dissolve lipids allows for faster penetration. If the fixation time is too long, it may produce hardening of the samples.
Procedure
60 ml 100º ethanol
30 ml chloroform
10 ml acetic acid
Notes
It is a good practice to use fresh fixative.
Products
100º ethanol
Chloroform
Acetic acid
Labware
Test tube
Bottles, containers