Tissue slices are sections of tissue cut from larger pieces or extracted organs and treated in a medium to gain insights into the working of the originating tissue or organ.
Unlike sections for histological studies, tissue slices for metabolic studies are not fixed and preserved. Rather, they are prepared immediately after the excision or after the animal has been put to sleep. Tissue slices are suspended in a medium, where they take up oxygen and nutrients, and trigger targeted biochemical processes.[1]
In other words, tissue slices must be thin enough for oxygen to diffuse into all layers but thick enough to contain unscathed and functioning cells.[2]
The followings are the techniques of tissue slice preparation for metabolic studies:
Regarded as the traditional preparation, free-hand sectioning only requires a razor blade and a skilled operator to slice the prepared tissue or organ into thin sections. The blade is moistened with an isotonic solution before sectioning to prevent tissue smearing during sectioning.
In a modified version, the razor blade is attached to a small glass plate, or a double-blade cutter is used instead. The glass plate acts as a guide, supporting the slicing direction and establishing a fixed sectioning thickness.
Microtomes are a type of sectioning instrument with an operating body, a blade holder, and a knife blade. Also, users can set a predefined slice thickness and control the movement or oscillation of the blade holder, guiding when and how the blade slices through the tissue sample.[3]
Microtome blades are exchangeable and can be made from steel, glass, or diamond.
Microtomes are also used to prepare tissue slices for histological studies and microscopic examinations. To learn more about the types of microtomes and what to look out for when choosing one, check out our article on the factors to consider when buying a microtome.
Tissue slicers are specifically designed to produce tissue slices for metabolic studies. Earlier versions of tissue slicers are manually operated. However, recent models have been fully automated and are often referred to as precision-cut tissue slicers.
Also called Krumdieck Tissue Slicer, is a modified microtome adapted to operate when the tissue sample is partially submerged in an isotonic solution. Users can define the slice thickness by setting the position of the blade, and the tissue sample is placed in a block in a reservoir assembly filled with the isotonic medium.
Slicing occurs when the block is moved to meet the blade, which is moved back and forth to slice the tissue. Sliced tissues are removed by a strainer inside the reservoir, which traps the slices and separates them from the medium.[4]
Also known as McIlwain Tissue Slicers is a type of tissue slicer inspired by the free-hand sectioning technique. The tool consists of a thin stainless steel blade, chopping arm, chopping plate, and mounting disc.
The tissue sample is placed in a Petri dish or directly on a chopping plate, which moves from left to right. Simultaneously, the blade connected to a chopping arm chops the sample, typically up to 200 strokes per minute. The thickness of the slice is determined by the moving speed of the chopping plate and the frequency of the strokes.[2]
Related Read: Preservation Techniques: Methods for Preserving Tissue Slices
Slicing techniques are essential in obtaining usable tissue slices. They must accommodate the features, size, and complexity of the target tissue or organ to ensure that the obtained slices can be used for metabolic studies.
Here are some points worth deliberating on when choosing a slicing technique and equipment:
Physical features and tissue complexity play significant roles in determining the most suitable slicing techniques. The physical organization of tissue is typically the functional structure, which must not be entirely destroyed by slicing.
For instance, soft tissue and tissue with extracellular space should not be exposed to fluid for a prolonged period. Wider blades can traumatize soft tissue more than narrow blades, which are typically equipped and found in tissue choppers. In contrast, hard tissue may benefit more from microtome preparation, which possesses a wider blade, including the Alabama Tissue Slicer.[2-4]
If the availability of the tissue sample is limited, consider foregoing free-hand sectioning. Instead, consider using microtomes or tissue slicers which produce slices with consistent size and thickness.
Along the same line, complex tissue with little known about its cellular organization or structure may benefit more from using free-hand sectioning or tissue choppers, because users can make observations and estimations as the tissue are being sliced.[2]
Apart from the tissue characteristics and availability, also consider the time and effort required to care for the slicing equipment when deciding to forego the free-hand slicing technique.
For example, consider choosing:
After several rounds of sectioning, the edge of the blade will become dull. Fixed blades must be sharpened, while removable or disposable blades must be exchanged. Disposable blades can be more expensive. Nonetheless, removable blades allow users the option of changing the blade material, which is crucial in obtaining usable tissue slices.
Modern tissue slicers can be manual, semi-automated, and fully automated. Manual models enable users to control most aspects of the slicing process. Automated tissue slicers are faster, and considered to produce more uniform tissue slices, but they are more expensive than manual and semi-automated equipment.
Tissue slice preparation is subjected to threats from movement and blade oscillation. Thus, slicing equipment should contain safety features such as locks and guards that contain the blade if it is damaged or discharged during the slicing.
The technique of preparing tissue slices is the heart of obtaining a snapshot of physiological and metabolic activities. Thin tissue slices with sufficient functional cells are keys to obtaining the metabolic data that represent the intact tissue and organ.
Free-hand sectioning is inexpensive and versatile but requires highly skilled users and can be wasteful. Microtomes and tissue choppers can produce tissue slices that are more consistent in size and thickness without relying on the user’s skills.
Are you looking for an affordable and versatile tissue slicer? Then check out our tissue chopper!
Monday – Friday
9 AM – 5 PM EST
DISCLAIMER: ConductScience and affiliate products are NOT designed for human consumption, testing, or clinical utilization. They are designed for pre-clinical utilization only. Customers purchasing apparatus for the purposes of scientific research or veterinary care affirm adherence to applicable regulatory bodies for the country in which their research or care is conducted.
