Volume of Tissue Blocks for Biological Microscopy
A biological microscope with a spotlight can move the spotlight up and down to achieve moderate brightness, and the aperture of the variable aperture can also be changed to achieve moderate brightness. If the light is from the sun, the spotlight can be raised appropriately and the aperture of the variable light can be enlarged appropriately. If the light is too strong, the spotlight can be lowered appropriately, and the aperture of the intersection can be reduced appropriately. If you still feel dazzling in this situation, you can choose to place an appropriate filter on the bracket under the spotlight. This oak can achieve a brightness that satisfies you. Of course, adjusting the upper and lower positions of the spotlight can change the aperture size of the light reading and select suitable filters, which requires a certain period of practice and experience.
A very important issue in biological microscopy is the process of sampling and isolating cells. After freeze-drying and resin embedding (FD), the frozen ultra-thin sections must be carefully processed to ensure that the 65 element content of each part is not damaged during observation and analysis. Due to the numerous steps and high cost involved in X-ray microanalysis, it is regrettable to draw incorrect conclusions if the analyzed cells are damaged or dead after prolonged and multi-step processing. The myocardial cells separated by gelatinase treatment have two forms, one is long rod-shaped and the other is circular. The latter refers to dying cells that are damaged during the process of cell separation.
The content and distribution of electrolytes in these two types of cells are very different under a biological microscope. Na is very high and K is extremely low in circular cardiomyocytes, and the concentration of Ca in linear dendrites is very high. After verification with other analytical methods, it has been proven that the high Na and low K in circular cells and the high Ca in mitochondria are the result of membrane damage during cell separation. The cold fixation method for cells and tissues often involves first quenching and then storing them in liquid nitrogen. Quenching fixation is crucial for the preservation effect. Living cells or fresh tissues are rich in water, and when quenched, the parts of the cells or tissues that come into direct contact with the refrigerant (especially when using liquid nitrogen for cooling) are often frozen and fixed first, forming a "shell" that hinders the central part of the cells from being crushed and fixed. Therefore, when conducting X-ray microanalysis, it is often found that ice crystals exist in the central part of larger cells. To prevent this situation from happening, a substance with a melting point higher than liquid nitrogen but lower by 806c is used as a refrigerant. There are many of these substances, but they are easy to obtain and the most affordable is concentrated propane (boiling point 42.120c, melting point 187.10c, molecular weight 44.1), which also has a fast cooling rate. But its disadvantage is that it is flammable.
