Tissue Dehydration (6-container)
Tissue Dehydration is the second stage of tissue preparation. At this stage, the Extra liquid in the tissue and also the fixative are removed from the tissue. Alcohol is one of the most famous water absorbers Which absorbs water from anything Get in touch with that. The Alcohol used in the tissue passage is ethyl Alcohol ,Its advantages are low toxicity, cheapness and High speed in tissue dehydration (Rapid dehydration).
Dehydration should be done gradually so that the tissue structure does not collapse
Because of that, ascending degrees of alcohol is used. In this way, it starts from a container of alcohol with low degrees, for example 70% and Absolute alcohol is used in the last container.
Alcohol containers are in ascending order as follow :
A container of alcohol 70%, A container of alcohol 80%, A container of alcohol 90%, A container of alcohol 96%, Two containers of Absolute alcohol . The duration of tissue stay in these alcohols for the first five containers is one hour to one and a half hours and 2 hours for absolute alcohols
Figure 1 : sequences of tissue processing
The volume of containers should be at least 5 times more than the volume of the tissue . In delicate tissues , especially those belonging to the fetus, lower grades such as 30% should be used.
If methyl alcohol is used due to restrictions in the preparation instead of ethyl alcohol, it should be noted that due to the toxicity of this alcohol and rapid saturation It needs more care. In this case, to prevent hardening of the tissues and difficulty in sectioning, the dehydration time should be reduced.
To soften hard tissues such as tendons and nails, it is recommended to add 4% phenol to containers containing 95% alcohol.