clearing part 2

Aniline oil

This is not normally utilized as a routine clearing agent but it is recommended for clearing embryos, insects and very delicate specimens, due to its ability to clear 70% alcohol without excessive tissue shrinkage and hardening

Clove oil

• This reagent causes minimum shrinkage of tissues.

• However, its quality is not guaranteed due to its tendency to become adulterated.

• Wax impregnation after clearing with _____ is slow and difficult.

• Tissues become brittle, aniline dyes are removed, and celloidin is dissolved.

• All of these, in addition to the expensiveness of the solution, make it unsuitable for routine clearing purposes.

Carbon tetrachloride

• may be used in clearing tissues for embedding.

• Its properties are very similar to that of chloroform although it is relatively cheaper.

• Its disadvantage is the same as that of chloroform.

• It produces considerable tissue hardening, and is dangerous to inhale on prolonged exposure due to its highly toxic effects.

Tetrahydrofuran

• is superior to ordinary dehydrating and clearing agents due to its ability to perform two processes at the same time, thereby shortening the total processing time and allowing more time for fixation.

• It is non-toxic but has offensive odor and should be used in a well-ventilated room

Dioxane

• miscible both with water and paraffin.

• It is used primarily when time is important because the tissues may be embedded with paraffin within 4 hours after fixation.

• The tissues are transferred to _____ straight from Bouin's fluid or a formalin fixative.

Dioxane

• is changed 3 times within 4 hours and the tissues are transferred directly to paraffin (3 changes are made in a total of 90 minutes).

• causes greater shrinkage than xylene does.

• In addition, it is dangerous.

• Fumes of ______ are toxic to human especially to the liver

TERPENES

• Isoprene polymers found in essential oils originally derived from plants, though some are now synthesized.

• Many _______ clear tissues and celloidin sections from 80%-95% alcohol, render tissues transparent and have a slow gentle non-hardening action.

TERPENES

• Most are generally regarded as safe though some have particularly strong odors which can be overpowering, requiring good laboratory ventilation.

• Moderately effective solvents, but they too are considered toxic.

• Solvents in this class also dry slowly, leave an oily residue on slides and are relatively expensive.

LIMONENE

• Volatile oil found in citrus peels which goes by several trade names.

• It is a natural oil found in the skins of citrus fruits, such as lemons or oranges, and in cooking is usually referred to as lemon or orange zest.

LIMONENE

• Obtained industrially by the steam distillation of orange peel which is a byproduct of the orange juice industry

• Clear, colorless fluid with a distinctly citrus aroma, not unpleasant to most people, although some do not like it

ORANGE OIL BASED CLEARING AGENTS

• Offer the clearing action with the lowest hazard rating of all xylene alternatives.

• the clearing action with the lowest hazard rating of all xylene alternatives.

• that are neither pure nor stable can break down to produce compounds which will interfere with staining procedures

CHLORINATED HYDROCARBONS

• Can be effective solvents, but they are considered toxic chemicals, posing serious health risks

• Government regulations have restricted most of the effective solvents in this class

COCONUT OIL

• Efficient substitute for xylene, as it is non-hazardous, less expensive and causes less shrinkage of the tissue

• It can be used as a de-alcoholization agent in the histopathological laboratory, without losing the quality of the histological details

• The only drawback associated with coconut oil, is its tendency to get solidified at a lower temperature. However, this can be overcome by performing the clearing procedure in an incubator, maintaining the required temperature.

BLEACHED PALM OIL

• Substitute as a clearing agent and dewaxing agent during staining gives good tissues, sections and histological slides

• In addition, bleached palm oil is nontoxic, nonhazardous, nonflammable, bio-degradable, economic, easy to handle, and readily available