Microscope Types

Microscope Types The use of a microscope is to provide a magnified view of objects (that are being analysed) that are otherwise to small to be seen by the naked eye. They can be described according to their illumination and lens arrangement. (i) Microscopes are able to use either light or electrons as their illumination source, which are respectively known as light powered and electron microscopes. (ii) Monocular microscopes have a single eye piece where as binocular microscopes posses two eye pieces, position side by side for simultaneous viewing with both eyes. (iii) A simple microscope consists of one single lens system where as a compound microscope consists of two main lens systems, an ocular and objective, which are superimposed over each other to provide greater magnification.

In Biology, microscopes can also be described according to some specific purpose such as dissecting microscopes, which are commonly referred, as dissectors are especially suitable for use while dissecting very small or delicate specimens. Microscopes are usually equipped with a series of interchangeable eyepiece lenses (oculars), each with different individual magnifications. Majority of ocular magnification is as followed: X4, X5, X6, X7, X8, X10, X12, and X15. On a typical monocular microscope objectives magnification found is as followed: X4 = SCANNING POWER = S.P. X10 = LOW POWER = L.P.

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X40 = HIGH POWER = H.P. To find the overall magnification factor obtained when using any microscope is calculated by the following mathematical formula: OCULAR magnification X OBJECTIVE magnification = OVERALL magnification The condenser lens is situated below the stage and causes light rays to converge on to the specimen situated on the stage, thus illuminating is adequately when magnified by the viewing lens. The amount of light passing through the condenser lens can be varied by opening and closing the iris diaphragm, situated at the bottom of the condenser. AIM: (i) To become familiar with the features and function of the monocular and stereo microscopes. (ii) To gain first hand experience in sketching scientific diagrams from prepared slides.

EQUIPMENT USED: Monocular microscopes, microscope lamp, lens cleaning tissue, lens-cleaning fluid, and various prepared slides. PROCEDURE: When using a monocular microscope, adjust the condenser lens so that it comes to rest against the bottom of the stage. Wind it down about 2mm below this level; now its in the ideal position. The iris diaphragm should also be readjusted each time a slide is moved from S.P to L.P. H.P. Obtain the first of the prepared slides and examine it under the scanning power. (ALWAYS begin with the S.P.

then the L.P. and finally the H.P.! NEVER the other way round!). Adjust the course focussing mechanism followed by the fine focus knob this will assure maximum clarity. Having adjusted the course focus whilst operating the scanning power setting, there is no need to use it again with either the L.P. or H.P. magnifications. Use only the FINE FOCUS with these magnifications.

N.B When operating either focussing mechanism, ALWAYS adjust the two wheels TOWARDS yourself, NEVER away from you! This will insure that the objective moves AWAY from the side NOT towards it, therefore the objective it CANNOT be rammed through the specimen slide! In Scientific sketching, try to keep BOTH eyes open, using one to peer down the microscope, and using the other eye to draw with. In addition, the sketches should ALWAYS include: A Title, Magnification factor, Labels (if possible) and be approximately -1 full page in size. DISCUSSION/CONCLUSION: Microscopes have many components, but one component was used at all times and most likely without even noticing you used it. That component is sits at the top of the microscope, which you look through and it is call the ocular. The ocular is interchangeable with different individual magnifications including X10, which was used in examining all prepared slides. Therefore, even if the objective magnification was X4 (S.P.), X10 (L.P.), or X40 (H.P.) the ocular did not change it was still the same magnification of X10. By using the mathematic formula of Ocular times, Objective will equal to the overall magnification you were using while examining a slide.

These magnifications were: OCULAR X OBJECTIVE = OVERALL MAGNIFICATION FACTOR X10 X X4 = 40 times = S.P. X10 X X10 = 100 times = L.P. X10 X X40 = 400 times = H.P. The specimens that are on slides come in many come colours and shape it depends on what specimen and which stain is used. In this experiment the prepared side specimens that were examined were an Ovary and Testes Colon Appendix that were pink, Striated Muscle was a purple red colour, and Grass Root Tip came in three colours red light blue and cream. Each slide was examined with Scanning power, Low power, and High power, there are tremendous amounts of differences between the sides.

Cause of out five the sides selected four are of from different parts of an animal and one is a plant slide. The main difference is between the magnification factors, scanning power (S.P.) is the only one that enables you to view all or most of the specimen section. Viewing in S.P. the specimen section structure is very cramped with every thing very close together (refer to sketches). When changing to low power (L.P.) the specimen section structure is larger where the section is a lot more free enabling the viewer to view in between the sections components (refer to sketches).

High power (H.P.) is where the specimen section structures is huge and more unattached compared to those of the S.P. and L.P. Therefore, in H.P. the structure can look total different from S.P. and L.P., the specimen section almost like its a completely different slide altogether.

By examining the sides specimens and the sketches, this was drawn while the slides specimens were under the microscope. Through these sketches and titles, it gave out enough information to seek out and research the suitable reference to complete this report. OVARY Cortex The cortex of the ovary is covered by a modified mesothelium, the germinal epithelium. Deep to this simple cuboidal to simple squamous epithelium is the tunica albuginea, the fibrous connective tissues capsule of the ovary. The remainder of the ovarian connective tissue is more cellular and is referred to as the stroma. The cortex houses the ovarian follicles in various stages of development. Primordial Follicles Primordial follicles consist of a primary oocyte surrounded by a single layer of flattened follicular (granulosa) cells.

Primary Follicular (A) Unilaminar Primary Follicles consists of a primary oocyte surrounded by a single layer of cuboidal follicular cells. Primary Follicular (B) Multilaminar Primary Follicles consists of a primary oocyte surrounded by several layers of follicular cells. The zona pellucida is visible. The theca interna is beginning to organised. Secondary (Vesicular) Follicle The secondary follicle is distinguished from the primary multilaminar follicles by its larger size, by a well-established theca interna and theca externa. Especially by the presence of follicular fluid in small cavities formed from intercellular space of the follicular cells. These fluids filled cavities are known as Call Exner bodies. Graafian (Mature) Follicles the graafian follicles is very large, the Call Exner bodies have coalesced into a single space and the antrum is filled with follicular fluid.

The wall of the antrum is referred to as the membrane granulosa and the region of the oocyte and the follicular cells jutting into the antrum is the cumulus oophorus. The single layer of follicular cells immediately surrounding the oocyte is the corona radiata. Long apical processes of these cells extend into the zona pellucida. The theca interna and theca externa are well developed; the former displays numerous cells and capillaries, where as the latter is less cellular and more fibrous. Atretic Follicles (A) Atretic follicles are in the state of degeneration. They are characterised in later stages by the presence of fibroblasts in the follicle and a degenerated oocyte.

Medulla (B) The Medulla of the ovary is composed of a relativity loose fibroblastic connective tissue housing and extensive vascular supply including spiral arteries and convoluted veins. Corpus Luteum (C) Subsequent to the extrusion of the secondary oocyte with its attendant follicular cells, the remnant of the Graafian follicle becomes partly filled with blood and is kn …


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