Histology Practical Microscope 2024 PDF

Histology practical Microscope 2024 Histology  It is science that deal with microscopic study of normal cell ,tissues and organs.  through sectioning, staining, and examining those sections under a microscope Introduction Microscopes are devices used to magnify small objects,...

Histology practical Microscope 2024 Histology  It is science that deal with microscopic study of normal cell ,tissues and organs.  through sectioning, staining, and examining those sections under a microscope Introduction Microscopes are devices used to magnify small objects, allowing them to be seen by the naked eye. Most microscopes have several different powerful lenses attached to them, allowing the viewer to inspect the content at more than 100 times its actual size. However, microscopes are extremely expensive, so you want to make sure you handle the device properly. Types of microscope There are many types of microscopes, and they may be grouped in different ways. The most common microscope (and the first to be invented) is: 1- Light (optical) microscope, which uses light to pass through a sample to produce an image. 2- Electron microscope, which uses the electron beams to pass through a sample to produce an image. the electron microscope has two types: (The transmission electron microscope and the scanning electron microscope)  Parts of light microscope 1- Body tube: (Ocular (eye lens), Revolving nose ,Objective lenses) 2- Arm: (Coarse (focus) adjustment, Fine (focus) adjustment) 3- Stage: (Slide Side screws and clips) 4- Light source(when use the micrscope light should be mild to modrate) 5- Condenser Microscope diagram labeling  Electron microscope Is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a higher resolving power than light microscopes and can reveal the structure of smaller objects. Comparison between light & electron microscope 100000 1 For proper light microscope examination the tissue must be thin stained tissue  Tissue preparation There are many methods for preparation of specimens for light microscopical examination. 1- Filming: as in tissue fluids e.g. blood film 2- Teasing or squeezing: as in muscle and nerve (by squeezing between two slides) 3- Stretching: as in elastic tissue e.g. fascia and membranes 4- Sectioning or cutting: it is the most common method for tissue preparation ,meaning cutting the tissue into thin sections using special instrument called microtome. Most slides are prepared by paraffin technique and referred to paraffin sections.  Preparation of paraffin sections 1- Obtaining the tissue (Must be fresh and few mm in thickness to achieve good fixation) Ideally, the tissue being analyzed should be less than 60 cm3 2- Fixation (Definition: Mean preservation of the tissue to state identical to that in life.) Functions: Keep the cell proteins in soluble, so they are not removed by subsequent steps Prevent postmortem changes to occur as putrefaction and autolysis Decrease postmortem shrinkage and distortion of cells during dehydration and clearing Change the refractive indices of various parts of cells make them more easily studied Make the cellular parts more stainable  Preparation of paraffin sections Example of fixatives substance : 1- 10%formalin or formal saline ( common) 2- Bouin (picric acid/formalin/acetic acid)