Biological microscope on the volume of tissue block
A biological microscope with a condenser can move the condenser up and down to make its brightness moderate, and also can change the aperture of the variable light analyzer to achieve a moderate brightness of 9b. If the light is in the sun, the condenser can be raised appropriately, and the aperture of the variable optical noise can be enlarged appropriately. If the light is too strong, the condenser can be lowered appropriately, and the aperture of the intersection can be reduced appropriately. If you still feel dazzling in this case, you can choose an appropriate filter and place it on the bracket under the condenser. This tussah can get a brightness that satisfies you. Of course, it is necessary to gain experience after a certain period of practice in adjusting the upper and lower positions of the condenser to change the aperture size of the optical reading and select suitable filters.
A very important problem of biomicroscope is that the content of 65 elements in each part after freeze-drying and resin embedding (FD) and freeze-drying must be carefully handled, so as not to damage the cells to be observed and analyzed. Because X-ray microanalysis not only involves many steps, but also costs a lot, it is very regrettable to draw a wrong conclusion if the cells analyzed are damaged cells or dead cells after long-term and multi-step treatment. For example, myocardial cells separated by collagenase treatment have two forms, one is long rod and the other is round. The latter is a dying cell that is damaged during cell separation.
The content and distribution of electrolytes in these two kinds of cells are very different under biological microscope. Na is very high and K is very low in round myocardial cells, and ca concentration in linear dendrites is very high. Compared with other analytical methods, it is proved that the high Na and low K in circular cells and the high ca in mitochondria are the results of cell membrane damage during cell separation. The cold fixation method of cells and tissues is often to fix them by quenching first, and then to store them in liquid nitrogen. Quenching fixation is very important for the preservation effect. Living cells or fresh tissues are rich in water. When quenching, it is often that the parts of cells or tissues that are in direct contact with cryoprotectants (especially when quenching with liquid nitrogen) are frozen and fixed first, thus forming a "shell", which hinders the freezing and fixing of the central part of cells. Therefore, when making X-ray microanalysis, 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 a drying temperature lower than 806c is used as a cooling agent. There are many such substances, but the most easily available one is concentrated propane (boiling point-42．120c, melting point-187．10c, molecular weight-44.1), which has the fastest cooling speed. But its disadvantage is flammability.
The biological microscope can put the muscle fiber on a special frame, and when the muscle fiber contracts to a certain phase and needs to be fixed, the nozzle is started immediately, so that the liquid propane is sprayed on the muscle fiber to quench and fix it. Then, the muscle fibers are taken out together with the rack and put into liquid nitrogen. If blood cells or separated cells are fixed, first centrifuge at low speed to concentrate the cells, transfer the cells to a silver small tube with good thermal conductivity, and put the small tube into liquid propane for freezing and fixing. When fixing rat pancreas in Hall laboratory, two steel blocks were precooled with liquid helium (or liquid nitrogen), and two copper blocks were placed in front of and behind the pancreas with pliers, so that the aunts were quenched and fixed. Tissue or cells can be stored for a long time after being quenched and fixed and transferred to liquid nitrogen.
