intro into microscopy

• Fixation is a histological technique used to preserve the structure of cells and tissues by preventing decay and autolysis.
• all cells are derived from a zygote, which is derived from 2 gametes, sperm and egg
• the 2 parts of the cell are cytoplasm and nucleus
• visualising cells is hard due to cells and tissues generally being colourless, thickness and autolysis
• autolysis is cell death due to lack of oxygen, caused by lysosomes
• chemical fixation can inhibit autolysis
• chemical fixation can be done by cross linking or coagulating
• light microscopy chemical fixation is only needed to stop autolysis as we cannot see membranes
• electron microscopy chemical fixation is needed to preserve lipid membranes
• light microscopy uses primary fixation, is embedded in paraffin wax and stained with H and E
• electron microscopy processing uses both primary and secondary fixation, is embedded in resin and stained with heavy metal
• the formula to determine the final magnification by a bionocular microscope is objective lens magnification x ocular lens magnification
• using the condenser diaphragm lever will increase the contrast of poorly stained sections
• cytology

  analysis of structure of cells with light microscopy
• autolysis is slowed by cold, sped up at 30, and inhibited at 50
• primary fixation uses formaldehyde
• LM is 5-7um
• EM is 70-90nm