Cytology & Histology

Cancer is nearly always diagnosed by an expert who has looked at cell or tissue samples under a microscope. In some cases, tests done on the cells’ proteins, DNA, and RNA can help tell doctors if there’s cancer. These test results are very important when choosing the best treatment options.Tests of cells and tissues can find many other kinds of diseases, too. For instance, if doctors are not sure a lump is cancer, they may take out a small piece of it and have it tested for cancer and for infections or other problems that can cause growths that may look like cancer.Cancer types can be grouped into histological categories, which include carcinoma, leukemia, lymphoma, myeloma, Sarcoma, mesothelioma.

Stem cells are characterized by their ability to differentiate and mature into other type of cells with specialized functions, they are identical cells found in the body which have the ability to continuously divide, self-renew themselves and differentiate into various kinds of cells. With the capacity of self-renewal, and differentiation, stem cells have been believed to be useful for treatment of a wide variety of diseases in the future, including stroke, traumatic brain injury, Alzheimer’s disease, Parkinson’s disease, spinal cord injury, baldness, blindness, deafness, wound healing, amyotrophic lateral-sclerosis, myocardial infarction, muscular dystrophy, In general stem cell transplantation of specific stem cells into the injured tissue to replace the lost cells is an adequate way to repair the tissue. 

Fine needle aspiration cytology is the most frequently used technique in cytology and is typically used to sample lumps found on the body. It involves using a thin, hollow needle to remove samples of tissue or fluid from an organ of the body or a lump found under the skin. Once the samples of cells have been removed, they are sent to the laboratory for further testing. Fine needle aspiration is usually done to identify the type of cells inside a lump or to see how well treatment of an existing lump is working. It is commonly used to investigate lumps found in the breast or thyroid gland but it can also be used in other parts of the body. It is a very useful way of detecting cancer.

Cytogenetics refers to the microscopic analysis of chromosomes in individual cells. Cytogenetics can be performed on fresh blood, bone marrow, prenatal specimens, and solid tissue specimens, and on fixed specimens. Changes that affect the number and/or structure of the chromosomes can cause problems with growth, development, and how the body functions. Changes to chromosome structure can disrupt genes, causing the proteins made from disrupted genes to be missing or faulty. Depending on size, location, and timing, structural changes in chromosomes can lead to birth defects, syndromes or even cancer. Alternatively, some chromosomal changes may have no effect on a person’s health.Cytogenetic analyses are commonly performed during pregnancy to determine if a fetus is at risk for common aneuplodies syndromes caused by structural abnormalities or to determine if extra or missing genetic material is present through cytogenetic microarray testing. 

Cytology screening is the ability to screen a predominantly negative cytology slide and notice occasional abnormalities among many thousands of cells. It is a method in which screening is done for the detection of early disease, through microscopic examination of a cellular specimen by inspecting each cell and structure present, usually at ×100 magnification with a mechanical stage, so that all areas are screened; the findings are evaluated and significant abnormalities are flagged for further evaluation by a cytopathologist. There are several methods in cytological screening: rapid rescreening, rapid pre-screening, automated screening, assessing personal and laboratory performance of primary screening.

Clinical Cytology is the diagnosis of disease through the microscopic examination of cells that are collected by various means. In clinical cytology cells are loosened from the tissue mass and transferred to a cytological slide, examined and evaluated. Cytological testing presupposes a high degree of expertise. Clinical Cytology has the advantage that collection of material can be undertaken without serious inconvenience to the patient; time and equipment requirements are modest and, where necessary, repeat testing is nearly always possible. 

New developments in the field of Cytology and Histology have challenged the way cytopathologists and histopathologists approach the diagnosis of a particular disease. The vast majority diseases are diagnosed in advanced clinical stages and are diagniosed by advanced cytological techniques. These include methods used in cell biology to culture, track, phenotype, sort and screen cells in populations or tissues, and molecular methods to understand cellular function. Advanced techniques in cytology and histology include fluorescence in situ hybridization (FISH), digital image analysis (DIA), immunohistochemistry, histomorphometry etc. Fluorescence in situ hybridization (FISH) is a technique that uses fluorescently labeled DNA probes to detect chromosomal alterations in cells. Through this advanced method one can detect various types of cytogenetic alterations, chromosomal abnormalities consistent with neoplasia in exfoliative and aspiration cytology specimens. Immunohistochemistry is a method that visualizes distribution and localization of specific antigen or cellular components in separated tissues, or tissue sections. 

Human histology is the scientific study of the fine detail of biological cells and tissues of humans using microscopes to look at specimens of tissues that have been carefully prepared using special processes called "histological techniques". It is often carried out by examining a thin slice called a "section" of tissue under a light microscope or an electron microscope. In order to distinguish different biological structures more easily and accurately histological stains are often used to add colours to or enhance the colours of certain types of biological structures differently from other types of structures that may be located next to and/or in contact with each other. 

Histological diagnosis can be defined as the microscopic examination of a biopsy or surgical specimen to study the manifestations of disease. In histological diagnosis, the tissue is taken off from the body by surgery, autopsy or biopsy then it is fixed over the glass slide as a method of stabilization and stained with dyes followed by examination under the microscope. The fixation is done to prevent tissue decay. Trained physicians, frequently licensed pathologists, are the personnel who perform histological diagnosis and provide diagnostic information based on their observations. Fixation, processing, and sectioning are the first three steps towards getting a diagnosis.

Disease histology is the microscopic examination of biological tissues to observe the appearance of diseased cells and tissues in very fine detail. It is the study of microscopic changes or abnormalities in tissues that are caused as a result of diseases. Disease histology involves the examination of a biopsy ie a surgically removed sample taken from a patient for the purpose of detailed study, the removed sample is processed using special histological techniques and carefully prepared histological sections of the specimen have been on the slides and stained using histology stains ready for observation using a microscope.

Histological Staining is a process where stains are usually selected according to the type of biological tissue to be observed. There are many different histology stains in use.Some histology stains are more widely used than others. Some histology stains are only used to study very specific types of biological tissue.

Cell differentiation is a continuous process where the less specialized or a primitive sell gets transformed into a more specialized one to carry complex processes of the cell. Differentiation occurs numerous times during the development of a multicellular organism as it changes from a simple zygote to a complex system of tissues and cell types. Differentiation continues in adulthood as adult stem cells divide and create fully differentiated daughter cells during tissue repair and during normal cell turnover.

Cell signaling is detection of the stimulus on the surface of the plasma membrane and transfer of the signal to the cytoplasmic side. Transmission of the signal to effector molecules and down a signaling pathway where every protein typically changes the conformation of the next down the path, most commonly by phosphorylation or dephosphorylation. The final effect is to trigger a cell’s response, such as the activation of gene transcription. Cells communicate by means of extracellular signaling molecules that are produced and released by signaling cells. These molecules recognize and bind to receptors on the surface of target cells where they cause a cellular response by means of a signal transduction pathway. 

Oral Cytology is the cytological technique in which diagnosis of oral surface lesions is done to detect cancer, viral disease, vesiculobullous dermatoses or fungal infection. In oral cytology, sample of superficial cells is used extensively in the diagnosis of less visible and accessible lesions. Oral cytology is used in monitoring patients following treatment for oral cancer and it is also used in monitoring matients following radiation therapy.