Freehand sectioning is a method of holding a blade or razor and cutting fresh or fixed material into thin slices, which are then mounted and used for microscopic observation. This method is simple and fast equipment, and can observe the living state and natural color of plant tissues in time. When doing paraffin sectioning, you can also use the freehand sectioning method first to observe its structure initially, to achieve the effect of targeting. At the same time, this method is also commonly used in the study of plant histochemistry. The disadvantage of this method is that the slices are often too thick and uneven in thickness, and the slices are not easy to be complete.
Operation method
freehand sectioning experiments
Materials and Instruments
Equipment: Move The basic process of the freehand sectioning experiment can be divided into the following steps: Long columnar organs such as roots and stems of plants or blocky structures such as tubers, roots and fruits are easy to hold during sectioning and are general materials for freehand sectioning. The specific steps for freehand sectioning of such materials are as follows. (i) Preparation Take a small petri dish, contain the right amount of water (sometimes need to use ethanol or dye solution, etc.), ready to blade (double-sided blade or razor), dropper, brush and other tools. (B) Take and shape the material Take the material to be sliced and trim it with a razor blade to a shape suitable for hand holding. For columnar organs, such as young roots and stems, a section of about 3 cm in length can be cut; for tubers, such as tubers and roots, a strip of about 3 cm in length and 5 mm × 5 mm in cross-section can be cut. When shaping the material, be sure to pay attention to the direction of the slices required by the experiment. (iii) Slicing Hold the material with three fingers of the left hand (thumb, index finger, and middle finger), keeping the upper edge of the material slightly higher than the index finger, the thumb slightly lower than the index finger, and the middle finger on top of the lower end of the material, so that the material can be pushed upward in conjunction with the index finger and the thumb during slicing. Hold the blade in the right hand, moisten the surface of the blade with water, place the blade flat on the index finger of the left hand, with the knife edge inward and parallel to the cross-section of the material, and pull the arm of the right hand backward (the wrist stays motionless), so that the blade slides along the side edge of the index finger from the left front to the right rear, and then cuts down the material at one time. The slicing process was repeated in this way, and after cutting off multiple slices, these slices were rinsed into the prepared petri dish by pipetting with water. (D) Mounting and staining Use a brush to select thin and transparent slices from the petri dish, place them on a slide, add 1 drop of water and cover with a coverslip to make a clinical slide. If the sections need to be stained, the following three methods can be used: ① Put an appropriate amount of staining solution in a Petri dish and immerse the thin section cut off with bare hands directly into it. ② Soak the slices in the water in the petri dish, pick them up with a brush and put them on a slide, add 1-2 drops of staining solution for staining. ③ Slice without staining first, directly mounted in water, add 1 drop of staining solution from the edge of the coverslip for staining if necessary.
① Blade (double-sided blade or razor)
② Dropper
③ Brush
④ Petri dish
⑤ Slide
Reagents:
① Slicing material
② Fresh water (ethanol or dye, etc.)
For too soft and not easy to hold the material, such as leaves or foliage materials (such as petals, etc.) to do freehand sectioning, it can be used to support some of the materials clamped before slicing, so that not only the operation is more convenient, but also to get a relatively thin section. The specific method is as follows: first prepare the blade, brush and a petri dish with water. Cut the support material (e.g., potato tubers, carrots, etc.) into strips about 2 cm long and 5 mm × 5 mm in cross-section, and make a longitudinal incision about 3 mm deep on one side. A long strip about 2 cm wide and 4 mm long is cut from the leafy material and placed into the incision in the support. Then, a freehand transverse cut was made in the support along with the material and the resulting slice was transferred to a petri dish containing water. The best section (without the support attached) is selected with a brush, placed on a slide and sealed with water. Staining may also be done if necessary.
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