Molecular Basis of Disease - Lab Report Example

Staining is one of the techniques used in the characterization of cancer cells. The most commonly used staining methods and Hematoxylin and Eosin staining. Generally the two methods have been used to differentiate between the nucleus and the cytoplasm of cells. Hematoxylin stains the nucleus purple while Eosin stains the cytoplasms pink. Cancer cells can also be stained particularly to differentiate them from other cells. However, it is imperative to note that there are preparation processes that should take place in order for tissue staining to be specific and relevant (Ahmed, 2007, p.490). Histopathology is a technique that involves the studying of disease development in tissues at the microscopic level.

In medicine histopathology refers to the examination of tissue biopsies that have already been prepared through histological techniques and placed on glass slides. The histological techniques used in sample preparation are tissue harvesting, fixation, embedding, mounting and staining of the tissue sections. Tissue harvesting: it involves the surgical removal of the tissue followed fixing to ensure that the tissue is stable and that it does not decay. Fixation: two methods are used; chemical fixation and freeze fixation.

Chemical fixation is done using formalin while freeze fixation is done using cryo-protectants such as OCT, TBS or Cryogel before freezing. Mounting: Tissues are placed in paraffin before being sectioned using a microtome before they are stained. Staining: The processed tissues are stained for viewing under a microscope. Objectives I. To prepare low and high power drawings of normal skin, breast and colon tissues. II. To prepare low and high power drawings of one diseased skin specimen or one diseased colon specimen. III. To prepare low power diagrams of all three diseased breast tissue specimens IV.

To answer the relevant questions in the practical manual Materials I. Light microscope. II. Blank plain paper. III. Pencil IV. Specimens: a) Colon - Normal human - Polyposis b) Skin - Normal human - Basal cell carcinoma - Malignant Melanoma - Squamous cell carcinoma c) Breast - Normal human - Lobular hyperplasia - Fibrodenoma Methods Human Colon The slide was held up to the light and the darker purple staining layer of the gastric mucosa (inner most layer of colon) identified. The slide was then place on the stage so that the inner layer of the colon was on top.

The upper edge of the specimen was then focused under low power magnification of the microscope (X40) and the following areas identified: gastric mucosa, muscularis mucosa, sub-mucosa and muscularis. After the major layers had been identified, the following layers were labeled: mucosa, colonic glands, gastric pits, sub-mucosa, muscularis mucosa (inner and outer layers) and blood vessels. A high power drawing of the gastric mucosa was the prepared and the following labeled: surface epithelium, colonic glands, goblet cells and lymphoid follicles.

The same procedure was repeated for diseases colon cells and the differences between tissue specimens identified. Human Skin The slide was held up to the light to identify the outer layer of the skin. The slide was then placed on the stage so that the surface of the skin was positioned on top. The upper edge of the specimen was focused under low