About Visikol® for Plant Biology

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What is Visikol for Plant Biology?

Visikol for Plant Biology is a clearing agent, used to render specimens transparent for optical analysis. Chloral hydrate has been used for over a century as a clearing agent, however its regulated status places it out of hands for a majority of microscopists. Developed specifically as a substitute for chloral hydrate in microscopic applications, Visikol for Plant Biology is especially useful in a number of fields of biological study.

Treatment with Visikol for Plant Biology results in a clarified specimen, allowing you to see through multiple vertical layers of the specimen without careful sectioning, remounting, or "rolling" the specimen, saving time in the lab.  

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How does Visikol for Plant Biology work?

Visikol for Plant Biology has a high refractive index when compared to other materials (see table below). Changes in refractive index within the specimen result in distortion of the image due to refraction (bending) of light. A high refractive index results in less refraction in the sample since many cellular materials have a high refractive index (cell walls: 1.425, cell membranes:  1.46-1.60) compared to the cytoplasm (approx. 1.35).

Visikol for Plant Biology has a similar refractive index to cellular components, as well as glass, which results in less refraction, and therefore a clearer, more transparent and glass-like specimen.

Why use a clearing agent? 

A clearing agent serves two purposes: 1) to increase transparency of the specimen to allow better visibility of internal components, and 2) to increase the refractive index of the material, allowing light to pass through without obstruction, resulting in a sharp, clear image. Clearing agents help in all aspects of optical sectioning, allowing you to traverse vertical slices of your specimen by adjusting the focus, rather than requiring complex sectioning techniques.

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Because of its high refractive index, more of the light that passes through the specimen makes it to the lens—and to the eye— resulting in a clearer, more detailed image.
Aqueous/Alcoholic media have a lower refractive index, resulting in more light being refracted away from the lens and less light reaching the eye.

Refraction is Important to Microscopy

Refraction causes distortion and bending of light which causes a loss of quality in image and detail. Refraction is caused when light passes between two materials with differing refractive indices. Cell walls and cell membranes typically have a higher refractive index (1.425, 1.46-1.60 respectively) than the cytoplasm (approx. 1.35). Using a medium like water or alcohol does not alter the differences in refractive index between the cellular materials. Clearing agents such as Visikol for Plant Biology increase the overall refractive index of the cytoplasm and the medium surrounding the cell walls and membranes, allowing light to pass through without refracting (bending). This results in an increase in transparency and quality of the image.

Table of refractive indices

Medium Refractive Index
Water 1.3330
Cytoplasm 1.35
Ethanol 1.3550
Lactic Acid 1.4250
Cell Wall 1.4250
Acidified Chloral Hydrate 1.4280
Visikol for Plant Biology 1.4450
Cell membrane 1.46-1.60
Glass (Pyrex) 1.475