Microscopy Lab Report

Topics: Cell, Cell nucleus, Mitosis Pages: 7 (2538 words) Published: April 25, 2013
1. Introduction

Microscopy is an essential technique not only in cell biology but natural science as a whole. We compared different types of microscopic techniques , according to the specimen used and the scope of the experiment. Two specimens, stained and unstained, containing CHO cells, were prepared, examined and analyzed under the microscope using bright field (HF), dark field (DF) and phase contrast (PH) settings. In addition, the four phases of cell division cycle were estimated.. Bright field microscopy was used for stained samples; while Dark field and Phase contrast microscopy are used for the non-stained specimens which can be illuminated from the side and top (for specimen that are not suitable to be observed under dark field microscopy) respectively. Koehler illumination is done to create high contrast illumination and improve microscopic image outcome. The aim was the study was multi fold; generating microscopic specimen of CHO cells in which we used observed with different microscopic visualization techniques as well as the different stages of mitosis. Then after we examined the crucial relationship between structure and function. Finally, the most efficient way of cleaning your hands and prevent bacterial growth, using was analyzed. The CHO cell samples were fixed; one with formaldehyde and another sample with maceration solution (ethanol/hydrochloric acid) and stained with orcein solution . In order to evaluate the levels of hygiene resulting from different methods of washing one's hands, colonies formed on agar plates with fingerprints after using : water, water with soap and 70% EtOH, were compared with one another and with unwashed hand colonies. The structure-function relationship is important for the identification of cell types. By identifying the cell organelles, we determined the tissues in the pictures showed as liver, kidney, pancreas, plasma, or accessory testis cells (Tedelind and Brix, 2013).

4. Discussion

4.1 Microscopy

As one of the three sections of the experiment, microscopic specimen of CHO cells were generated and used to learn about microscopic visualization techniques as well as the different stages of mitosis examined cell division in CHO cells. The variation on the contrast techniques are based on differences with the source of the light for the light microscopy. With light microscopy the specimen is illuminated from below and thus requires stained specimen; this enhances visualization of the cell or certain cellular components under a microscope. The use of different stains enables one to preferentially stain certain cell components (such as a nucleus or a cell wall) or the entire cell. Most stains can be used on fixed, thus non-living cells, while only some can be used on living cells (Basic cell staining, 2013). Dark field microscopy, where specimen is illuminated from the side, is ideal when dealing with specimen that are unstained, transparent and absorbing little to no light. However, most of the details in cells are undetectable in bright field microscopy because there is too little contrast between structures with similar transparency and there is inadequate natural pigmentation. Thus we use the great range in refractive index various organelles show, providing an opportunity to distinguish them. By this a non-visible phase shift is transformed into differences in the amplitudes of light waves, which are visible for the human eye (Phase contrast microscopy, 2012). Comparing all three we found stained samples in phase contrast the best as we were able to detect most details including the cell cycle with it.

In Interphase the cell is engaged in metabolic activity and preparation for mitosis (the next four phases in cell division). Chromosomes are not clearly seen in the nucleus, although the nucleolus could still be visible. The centrosome is the major microtubule organizing center in animals where a microtubule radial array originates. Whereas in...
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