Measurement of the physical and chemical characteristics of cells is called cytometry. Flow cytometry is a simple and rapid method for the quantitative and qualitative analysis of single-cell suspensions. Flow cytometry is a laser-based technology whereby cells are suspended in a fluid stream and stimulated by a laser; the cells scatter and/or emit light which is then detected by Photomultiplier-Based Tubes (PMTs). All parameters measured can be divided into two main groups:
1) Those related to light scattering, which mainly reflects the size of the cell and its internal complexity and
2) Those related to fluorescence.
These are associated with the presence of one or more fluorochromes inside the cell or attached to the cell surface membrane, either naturally (autofluorescence) or artificially (e.g., using fluorochrome conjugated monoclonal antibodies). Flow cytometers are composed of three main systems: fluid system, optical system and electronic system. There are two different types of flow cytometry - named as non-sorting and sorting. Non-sorting type can perform light scattering and fluorescence emission while the sorting type has the ability to sort particles as well. Fluorescent Activated Cell Sorters (FACS) are flow cytometers that have the capacity to sort fluorescent-labeled cells from a mixed cell population. With the flexibility of flow cytometry, and the reliability of results, this technology has become an essential veterinary research instrument with important clinical diagnostic capabilities, particularly in the fields of immunology and hematology. It is possible to perform functional tests, biological evaluations of compounds, purify cell populations even when they are present in a low proportion in the sample. The most common use of flow cytometry is in the identification of markers on cells, particularly the immune system or immunophenotyping. It is one of the most popular and versatile techniques for studying apoptosis, and cell viability. It can also use to evaluate cell proliferation, metabolic activity and intracellular signalling. Flow cytometry has been extensively used to study mammalian sperm in the areas of reproductive toxicology (to monitor effects from environmental, occupational and therapeutic exposures), veterinary science (to preselect the gender of offspring by sorting X- and Y-chromosome-bearing sperm) and clinical andrology (to assess individual fertility potential). Flow cytometry is most often applied in veterinary oncology to diagnose lymphoid neoplasia and leukemia, and can also be used to assess neoplastic and non-neoplastic marrow conditions.
International Journal of Veterinary Sciences and Animal Husbandry
