Advances in Microscopy

Developments in Microscopy

• Microscopes were first invented in the 17th century, allowing for the discovery of cells.
• As microscopes improved, our understanding of cells and tissues improved dramatically.

Compound Light Microscopes

• Allowed for the discovery of bacteria, chromosomes, mitosis, and meiosis.
• Limited to magnifications of 400X, beyond which it becomes harder to produce a focused image.

Electron Microscopes

• Use beams of electrons to produce high-resolution images.
• Can magnify objects up to 1,000,000X their original size.
• Drawbacks: cannot produce color images, and cells need to be dead to examine them.

Fluorescent Stains

• Use intense light sources (lasers, high power LED) to produce bright images.
• The light is absorbed by the sample and re-emitted, generating high-resolution images.
• Most cell parts are white or colorless and need to be stained to be visible.

Immunofluorescence

• An advancement in fluorescent staining that uses antibodies to bind to specific chemicals (antigens) in the sample.
• Produces multi-colored fluorescent images showing where different chemicals are located.

Freeze-Fracture Electron Microscopy

• Produces images of surfaces within cells.
• A cell is rapidly frozen, fractured, and then etched to enhance the texture.
• A replica is taken of the fracture and can be examined with an electron microscope.
• Best for showing the texture of a cell part.

Cryogenic Electron Microscopy

• Typically used to research the structure of proteins.
• A protein solution is flash frozen and analyzed with an electron microscope.
• A computer algorithm analyzes the different patterns and generates a 3D image of the protein structure.