NAME: NAVERA ZAHEER CLASS: BS IV YEAR DEPART:APPLIED BIOCHEMISTRY TOPIC:MICROSCOPY (LIGHT MICROSCOPY) SUBMITTED TO: Dr. FARAH TARIQ MICRPSCOPE:An instrument which is used to observed organisms ,which arenot been able to see with our naked eyes.It is used for viewing objects such as micro organisms whichare too small to be visible with human eyes.
It is an important tool in modern erafor the visualizing of the microbial world the choice of microscope dependsupon the size of the object, nature of specimen, and all the purposes of themicroscopic observations. HISTROY: Firstly, ROBERT HOOKE an English Scientist invented anoptical microscope in 1665.The main purpose is to visualize biologicalspecimen. After 10 years ANTON VON LEEUWENHOEK invented a simple glass lens ofconvex surface. The main purpose is to observed bacteria, fungi, blood cells, plants,protozoa etc.Then after Ernest Abbe in 1870 intenvetd compound microscopy.
Themain purpose is to create microscope lens that helps to create much magnifiedand fine image. OIL IMMENSE LENSES:Oil immense lenses are used in microscope; allow improvingresolution and classifying image.Ø 10X Low power lenses , used forblood cells.Ø 40X High power, used forProtozoa ,FungiØ 100X Oil immersion lenses, used forbacteria except virusesMicroscopes are classified in various branches, which are asfollows:v Light microscopyØ Bright field microscopyØ Dark field microscopyØ Phase contrast MicroscopyØ Fluorescence MicroscopyØ Confocal Microscopyv Electron MicroscopyØ Transmission Electron MicroscopeØ Scanning Electron MicroscopeØ Scanning Transmission Electron MicroscopeLIGHT FIELD MICROSCOPY:Light is directly passed through a specimenthat may be stained or unstained .It has a single len which is used tomagnified image with low magnification.Bright fieldmicrocopy:PURPOSE:It formed image when light is transmittedthrough the specimen.
PRINCIPLE:Specimen being dense and more opaque then itssurrounding observed some of this light, the rest of the light is transmitteddirectly up through the ocular into the field.EXAMPLE:Specimen should beexamine by BFM are protozoan cell E.g. Amoeba,paramecium.As a result specimenproduced as image that is darker than its surrounding with brightly illuminatedfield.
USES:It is a multipurpose instrument that can be used for both alive ,unstainedmaterials ,and preserved stained materials. DARK FIELD MICROSCOPY: PURPOSE: Bright Fieldmicroscopy can be adapted as dark field microscopy by adding a special disccalled stop to the condenser.PRINCIPLE:The stop blocks all the light from entering into the objective lens exceptperipheral light i.e.
referred as the light reflected off the sight of thespecimen its self. The resulting image is particularly stricken one i.e. brightilluminated specimen surrounding by a dark filed.USES:Ø The most effectiveuse of DFM is to visualize living cell that could be distorted by dying or heator can’t be stain with the visual method.Ø It can outline theorganism shape and permit rapid identification of swimming cell that mightappear in dental and other infections.Ø It can’t reveal fineinternal structure.