The use of a microscope is to provide a magnified view of objects (that arebeing analysed) that are otherwise to small to be seen by the naked eye. Theycan be described according to their illumination and lens arrangement. (i)Microscopes are able to use either light or electrons as their illuminationsource, which are respectively known as light powered and electron microscopes. (ii) Monocular microscopes have a single eye piece where as binocularmicroscopes posses two eye pieces, position side by side for simultaneousviewing with both eyes. (iii) A simple microscope consists of one single lenssystem where as a compound microscope consists of two main lens systems, anocular and objective, which are superimposed over each other to provide greatermagnification.Order now
In Biology, microscopes can also be described according to somespecific purpose such as dissecting microscopes, which are commonly referred, asdissectors are especially suitable for use while dissecting very small ordelicate specimens. Microscopes are usually equipped with a series ofinterchangeable eyepiece lenses (oculars), each with different individualmagnifications. Majority of ocular magnification is as followed: X4, X5, X6, X7,X8, X10, X12, and X15. On a typical monocular microscope objectivesmagnification found is as followed: X4 = SCANNING POWER = S. P.
X10 = LOW POWER =L. P. X40 = HIGH POWER = H. P.
To find the overall magnification factor obtainedwhen using any microscope is calculated by the following mathematical formula:OCULAR magnification X OBJECTIVE magnification = OVERALL magnification Thecondenser lens is situated below the stage and causes light rays to converge onto the specimen situated on the stage, thus illuminating is adequately whenmagnified by the viewing lens. The amount of light passing through the condenserlens can be varied by opening and closing the iris diaphragm, situated at thebottom of the condenser. AIM: (i) To become familiar with the features andfunction of the monocular and stereo microscopes. (ii) To gain first handexperience in sketching scientific diagrams from prepared slides. EQUIPMENTUSED: Monocular microscopes, microscope lamp, lens cleaning tissue,lens-cleaning fluid, and various prepared slides. PROCEDURE: When using amonocular microscope, adjust the condenser lens so that it comes to rest againstthe bottom of the stage.
Wind it down about 2mm below this level; now its inthe ideal position. The iris diaphragm should also be readjusted each time aslide is moved from S. P to L. P. H.
P. Obtain the first of the prepared slides andexamine 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 focussingmechanism 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 eitherfocussing mechanism, ALWAYS adjust the two wheels TOWARDS yourself, NEVER awayfrom you! This will insure that the objective moves AWAY from the side NOTtowards it, therefore the objective it CANNOT be rammed through the specimenslide! In Scientific sketching, try to keep BOTH eyes open, using one to peerdown the microscope, and using the other eye to draw with. In addition, thesketches should ALWAYS include: A Title, Magnification factor, Labels (ifpossible) and be approximately -1 full page in size. DISCUSSION/CONCLUSION:Microscopes have many components, but one component was used at all times andmost likely without even noticing you used it. That component is sits at the topof the microscope, which you look through and it is call the ocular. The ocularis interchangeable with different individual magnifications including X10, whichwas used in examining all prepared slides.
Therefore, even if the objectivemagnification was X4 (S. P. ), X10 (L. P.
), or X40 (H. P. ) the ocular did not changeit was still the same magnification of X10. By using the mathematic formula ofOcular times, Objective will equal to the overall magnification you were usingwhile examining a slide. These magnifications were: OCULAR X OBJECTIVE = OVERALLMAGNIFICATION FACTOR X10 X X4 = 40 times = S. P.
X10 X X10 = 100 times = L. P. X10X X40 = 400 times = H. P. The specimens that are on slides come in many comecolours and shape it depends on what specimen and which stain is used. In thisexperiment the prepared side specimens that were examined were an Ovary andTestes 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 slidewas examined with Scanning power, Low power, and High power, there aretremendous amounts of differences between the sides. Cause of out five the sidesselected 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 thingvery close together (refer to sketches). When changing to low power (L. P. ) thespecimen section structure is larger where the section is a lot more freeenabling the viewer to view in between the sections components (refer tosketches).
High power (H. P. ) is where the specimen section structures is hugeand 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 sectionalmost like its a completely different slide altogether. By examining thesides specimens and the sketches, this was drawn while the slides specimens wereunder the microscope. Through these sketches and titles, it gave out enoughinformation to seek out and research the suitable reference to complete thisreport. OVARY Cortex The cortex of the ovary is covered by a modifiedmesothelium, the germinal epithelium. Deep to this simple cuboidal to simplesquamous epithelium is the tunica albuginea, the fibrous connective tissuescapsule of the ovary.
The remainder of the ovarian connective tissue is morecellular and is referred to as the stroma. The cortex houses the ovarianfollicles in various stages of development. Primordial Follicles Primordialfollicles consist of a primary oocyte surrounded by a single layer of flattenedfollicular (granulosa) cells. Primary Follicular (A) Unilaminar PrimaryFollicles consists of a primary oocyte surrounded by a single layer ofcuboidal follicular cells. Primary Follicular (B) Multilaminar PrimaryFollicles consists of a primary oocyte surrounded by several layers offollicular cells.
The zona pellucida is visible. The theca interna is beginningto organised. Secondary (Vesicular) Follicle The secondary follicle isdistinguished from the primary multilaminar follicles by its larger size, by awell-established theca interna and theca externa. Especially by the presence offollicular fluid in small cavities formed from intercellular space of thefollicular cells. These fluids filled cavities are known as Call Exnerbodies. Graafian (Mature) Follicles the graafian follicles is very large,the Call Exner bodies have coalesced into a single space and the antrum isfilled with follicular fluid.
The wall of the antrum is referred to as themembrane granulosa and the region of the oocyte and the follicular cells juttinginto the antrum is the cumulus oophorus. The single layer of follicular cellsimmediately surrounding the oocyte is the corona radiata. Long apical processesof these cells extend into the zona pellucida. The theca interna and thecaexterna 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 inlater stages by the presence of fibroblasts in the follicle and a degeneratedoocyte.
Medulla (B) The Medulla of the ovary is composed of a relativityloose fibroblastic connective tissue housing and extensive vascular supplyincluding spiral arteries and convoluted veins. Corpus Luteum (C) Subsequentto the extrusion of the secondary oocyte with its attendant follicular cells,the remnant of the Graafian follicle becomes partly filled with blood and isknown as the corpus hemorrhagicum. Cells of the membrane granulosa aretransformed into large granulosa lutein cells. Moreover, the cells of the thecainterna also increase in size to become theca lutein cells, although they remainsmaller than the granulosa lutein cells.
Corpus Albicans (D) The corpusalbicans is a corpus luteum that is in the process of involution ahyalinization. It becomes fibrotic with few fibroblasts among the intercellularmaterials. Eventually, the corpus albicans will become scar tissue on theovarian surface. TESTES Capsule The fibromuscular connective tissue capsuleof the testes is known as the tunica albuginea, whose inner vascular layer isthe tunica vasculosa. The capsule is thickened at the mediastinum testis fromwhich septa emanate subdividing the testis into approximately 250 incompletelobuli testis, with each containing one to four seminiferous tubules embedded ina connective tissue stroma.
Seminiferous Tubules Each highly convolutedseminiferous tubule is composed of a fibromuscular tunica propria, which isseparated from the seminiferous epithelium by a basal membrane. SeminiferousEpithelium The seminiferous epithelium is a composed of sustentacularsertoli cells and a stratified layer of developing male gametes. Sertoli cellsestablish a blood testis barrier by forming occluding junctions with eachother, thus subdividing the seminiferous tubule into adluminal and basalcompartments. The basal compartments house spermatogonia A (both light anddark), spermatogonia B, and the basal aspects of sertoli cells. The adluminalcompartment contains the apical portions of sertoli cells primary spermatocytes,secondary spermatocytes, spermatids, and spermatozoa. Tunica Propria Thetunica propria consist of loose collagenous connective tissue, fibroblasts, andmyoid cells.
Stroma loose, vascular, connective tissue stroma surroundingseminiferous tubules houses small clusters of large, vacuolated appearingendocrine cells, in the interstitial cells (of leydig). COLON, APPENDIX Mucosathe mucosa presents no specialised folds. It is thicker than that of thesmall intestine. Epithelium (A) The simple columnar epithelium has gobletcells and columnar cells. Lamina Propria (B) The crypts of lieberkhn ofthe lamina propria are longer than those of the small intestine. They arecomposed of numerous goblet cells, a few APUD cells, and stem cells.
Lymphaticnodules are frequently present. Muscularis Mucosae (C) The muscularismucosae consist of inner circular and outer longitudinal smooth muscle layers. Submucosa The submucosa resembles that of the jejunum or ileum. MuscularisExterna The muscularis externa is composed of inner circular and outerlongitudinal smooth muscle layers. The outer longitudinal muscle is modifiedinto teniae coli, three flat ribbons of longitudinally arranged smooth muscle.
These are responsible for the formation of haustra coli (sacculation). Auerbachs plexus occupies its position between the two layers. Serosa (A)The colon possesses both serosa and adventitia. The serosa presents small, fatfilled pouches, the appendices epiploicae.
Appendix (B) The lumen of theappendix is usually stellate shaped, and it may be obliterated. The simplecolumnar epithelium covers a lamina propria rich in lymphatic nodules and somecrypts of lieberkhn. The muscularis mucosae, submucosa, and muscularis externaconform to the general plan of the digestive tract. It is covered by serosa. Anal Canal (C) The anal canal presents longitudinal folds, anal columns,that become jointed at the orifice of the anus to form anal valves andintervening anal sinuses. The epithelium changes from the simple columnar of therectum, to simple cuboidal at the anal valves, to epidermis at the orifice ofthe anus.
Circumanal glands, hair follicles, and sebaceous glands are presenthere. The submucosa is rich in vascular supply, while the muscularis externaforms the internal anal sphincter muscle. An adventitia connects the anus to thesurrounding structures. STRIATED MUSCLES Longitudinal Section (A) Connectivetissue elements are clearly identifiable because of the presence of the nucleithat are considerably smaller than those of cardiac muscle cells. The connectivetissue is rich in vascular components, especially capillaries.
The endomysium ispresent but indistinct. Longitudinal Section (B) Cardiac muscle cells fromlong, branching, and anastomosing muscle fibers Bluntly oval nuclei are large,are centrally located within the cell, and appearing somewhat vesicular. A and Ibands are present but are not as clearly defined as in skeletal muscle. Intercalated discs, marking the boundaries of contiguous cardiac muscle cell,may be indistinct unless special staining techniques are used.
Purkinje fibersare occasionally evident. ROOT TIP As root tissues differentiate behind thegrowing tip, they form a pattern of cylinders (tubes) within the cylinders. Eachcylinder is composed of tissue that has a specific role to play for the plant. Epidermis The outermost cylinder is only cell in thickness and is called theepidermis.
This encloses and protects the underlying tissues. Some epidermiscells differentiate into hair cells. These stick out into surrounding soilspaces and absorb water and selected mineral ions. Cortex Parenchyma A verythick cylinder is found just under the epidermis. This called the cortex orcortex parenchyma. Parenchyma cells store excess nutrients, usually in the formof starch.
These cells are loosely packed so that the spaces between them candirect water and mineral ions coming from root hairs and cortex spaces anddirects them into the central vascular core. Pericycle Another thin cylinderis found under the endodermis, the pericycle. Pericycle cells can function likemeristem and mitotically produce secondary or branch roots. The pericycle alsoconstitutes the outer boundary of the vascular core, a structure that containsthe internal, liquid transport highways of the plant in the form of highlyspecialised tube like or conducting tissues. Vascular Cylinder The vascularcylinder is comprised of tissues that transport nutrients.
Water and mineralions taken in by root hairs and concentrated into the core by the endodermis aretransported up into the plant shoot by xylem tubes. Sugar rich fluid,sucrose, made in the leaves as glucose is transported by phloem sieve tubes intothe root core, where it is distributed to root cells for energy production orstorage as starch in the cortex parenchyma. Xylem and phloem tissues areexcellent examples of how cell structure dictates function. Xylem Cells (A)Xylem cells have to die before they can serve the transport needs of the plant. Dead xylem cells leave behind a thick, hollow, tubular wall, which joins end toend with other xylem walls to form a microscopic but strong and fixable tube,which extends from root to leaf. Xylem walls have slit like openings orpits, which provide for the sideways transfer of water and mineral ions intosurrounding tissue.
Close examination of these wall shows that their thicknessis due to cellulose and a cement like substance call lignin. Lignin creates thewood in woody plants some walls are reinforced with internal rings or spirals. These rings of lignin help to support the plant. Xylem tubes are sometimescalled vessels, i.
e. composed of vessel cells, or elements. Primitive plantssuch as pines and firs have tracheid xylem which thinner walls and tapered ends. Phloem (B) Phloem is made up of two basic cell types, both of which areliving when they serve the transport needs of the plant.
The lager cell type isa sieve tube member; the small is a companion cell. The sieve tubes member,though living, does not have a nucleus and therefore does not control its ownmetabolism. What the needs it has are apparently provide for by the tinycompanion cell that is attached to the sieve tube member. Sieve tubes membersare very much smaller and have thinner walls than xylem, but like xylem, theyjoin end to end to form sieve tubes that extend leaves to roots.
These taketheir name from the tiny, sieve like pores in their walls and the larger porescalled sieve plates that separate one member from another. Pores provide for thehorizontal and vertical movement of the sugar rich sap that slowly movesdown from the leaves, supplying energy, and elements to all plant tissues. Largeparenchymal cells called pith may also be associated with the vascular cylinderphloem.