Biological Microscopy So far, cold fixation, frozen ultrathin section and freeze-drying are routine methods for tissue and cell x-ray microsections. The details of this method are explained as follows:

For biological microscopes with a condenser, the condenser can be moved up and down to make the brightness moderate, and the aperture of the variable light can also be changed to achieve a moderate 9b brightness. If the light is sunny, the condenser can be raised up appropriately, and the aperture of the variable light source can be appropriately enlarged. If the light is too strong, the condenser lens can be lowered appropriately, and the aperture of the intersecting light can be appropriately reduced. If you still feel dazzling in this case, you can choose an appropriate filter and place it on the bracket under the condenser. This oak will be able to obtain the brightness that satisfies you. Of course, adjusting the upper and lower positions of the condenser, adjusting the aperture size of the variable optical reading and selecting a suitable filter requires a certain period of practice to gain experience.

A very important issue in biological microscopy is that in the process of sampling and separating cells, after freeze-drying and resin embedding (FD), after freezing ultra-thin aggregates, and after freeze-drying, the content of 65 elements in each part must be carefully handled. The cells to be analyzed cannot be damaged. Because X-ray microanalysis not only involves many steps, but also costs a lot. If the analyzed cells are damaged cells or dead cells after a long time and multi-step processing, it is very regrettable to draw wrong conclusions. For example, cardiomyocytes separated by collagenase treatment have two shapes, one is long rod-shaped, and the other is round. The latter are dying cells that are damaged during cell isolation.

Biomicroscopy The amount and distribution of electrolytes in these two types of cells are quite different. Na is very high and K is very low in circular cardiomyocytes, and the concentration of ca in nematodes is very high. After checking with other analysis methods, it is proved that the high Na and low K of round cells and the high Ca in mitochondria are due to the damage of the cell membrane during the cell separation process. The ice-cold fixation method of cells and tissues is usually to adopt quenching and fixation first, and then store them in liquid nitrogen. Quenching fixation is very important for the effect of preservation. Living cells or fresh tissues are rich in water. When quenching, the parts of the cells or tissues that are in direct contact with the crushed refrigerant (especially when quenching with liquid nitrogen) are often frozen and fixed first, thus forming a "shell", which hinders The central parts of the cells were crushed and cold-fixed. Therefore, when doing X-line micro-area analysis, it is often found that there are ice crystals in the center of larger cells. In order to prevent this from happening, a substance with a melting point higher than that of liquid nitrogen but lower than that of 806c is used as a broken refrigerant. There are many such substances, but the cheapest one is concentrated propane (boiling point - 42.120c, melting point - 187.10c, molecular weight 44.1), and the cooling speed is the fastest. But its disadvantage is that it is flammable.

Biological microscope can put the muscle fiber on a special rack, so that when the muscle fiber contraction reaches a certain phase and needs to be fixed, immediately start the nozzle to spray liquid propane to the muscle fiber to quench and fix it. Then the muscle fibers together with the frame were taken out and put into liquid nitrogen. If fixing blood cells or isolated cells, first concentrate the cells by centrifugation at low speed, transfer the cells to a silver vial with good thermal conductivity, place the vial in liquid propane, and freeze for fixation. When fixing the rat pancreas in the Hall laboratory, the two steel blocks were pre-cooled with liquid helium (or liquid nitrogen), and the two copper blocks were clamped with forceps and placed on the front and back of the pancreas to quench and fix the pancreas. Tissues or cells can be stored in liquid nitrogen for long-term storage after quenching and fixing.

Biological Microscopy In addition to the most respected frozen ultrathin section method, here is another deposition technique used by scientists. A substance is added to form a sediment with the component to be analyzed to immobilize it prior to analysis, and the sediment is then analyzed. For example, people often use oxalate and pyroantimonate to deposit ca in muscle cells. The former is not sensitive enough to the low concentration of Ca in the cytoplasm; pyroantimonate is more sensitive and can form electron-dense deposits with free Ca in the brain, but pyroantimonate is not compatible with sodium, manganese, barium, iron Deposits are also formed and are less specific. The specimen preparation process is similar to the preparation of ordinary transmission electron microscope ultrathin section specimens, the difference is that 3 percent potassium pyroantimonate (phosphate buffer saline, pH 7.6) was fixed for 6 hours before fixation, and on the stained muscle ultrathin sections, Black deposits were seen in the midlines of bands A and 2 of each sarcomere, and unstained sections were used for X-ray microanalysis. Diaminobenzidine tetrahydrochloride (DAB) was used to precipitate heme-containing substances and so on. The combination of histochemical precipitation reaction and x-ray micro-differentiation bridge can be considered in laboratories that do not have frozen ultrathin section conditions. Semi-quantitative can be done according to the peak height of the elements to be analyzed