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fluorochrome 280 follicular hyperplasia
Radioactive labeling is usually employed if the substance to
be detected is present in minute amounts. Fluorescent labeling,
however, provides simplicity of technique and precise
microscopic observation of fluorescence. Fluorescent microscopic
preparations require several hours and permit localization
at the cellular level, whereas autoradiograms require
a longer period and are localized at the tissue level. Either
fluorescein (apple-green fluorescence) or rhodamine (reddishorange
fluorescence) compounds may be used for tracing.
fluorochrome
A label such as fluorescein isothiocyanate or rhodamine
isothiocyanate used to label antibody molecules or other
substances. A fluorochrome emits visible light of a defined
wavelength upon irradiation with light of a shorter wavelength
such as ultraviolet light.
fluorodinitrobenzene
Refer to dinitrofluorobenzene (DNFB).
fluorography
A method used to identify radiolabeled proteins following
their separation by gel electrophoresis. A fluor such as
diphenyl oxazole is incorporated into the gel, where it emits
photons on exposure to a radioisotope. After drying, the gel
is placed on x-ray film in the dark.
FLU/v
A newly developed vaccine against influenza that
focuses on parts of the virus that do not mutate from year to
year. Murine studies show that 57% of mice given the new
vaccine survived lethal doses of the flu compared with no
mice that received a controlled flu vaccine. This new vaccine
purportedly protects permanently against all strains of
influenza including bird flu. Current vaccines only protect
against specific strains for a limited time. Investigators
attempt to predict which version will be prominent in the
forthcoming flu season. Because of the propensity for the
influenza virus to mutate, the vaccine for a particular year
may not be as effective as hoped, and new vaccines must be
developed each flu season. FLU/v can be produced faster
and more easily than traditional vaccines.
Fluorescence of focal segmental glomerulosclerosis.
fog fever
An episode of acute respiratory distress in cows approximately
7 days after their removal to a pasture where hay has been
recently cut. They may die within 1 day, developing pulmonary
edema with extensive emphysema. This disease may present
as an atopic allergy in sensitized animals exposed to
grass proteins, pollen, and fungal spores. A nonimmunologic
intoxication has also been suggested as a cause. Cattle may also
suffer a reaction that resembles farmer’s lung in humans if they
have been fed hay containing Micropolyspora faeni spores.
Precipitating antibodies are present in their sera.
follicle
Circular or oval areas of lymphocytes in lymphoid tissues rich
in B cells. They are present in the cortices of lymph nodes
and in the splenic white pulp. Primary follicles contain small
and medium-sized B lymphocytes. They are demonstrable in
lymph nodes prior to antigenic stimulation. Once a lymph node
is stimulated by antigen, secondary follicles develop. They
contain large B lymphocytes in the germinal centers, where tingible
body macrophages (those phagocytizing nuclear particles)
and follicular dendritic cells are present.
follicle-associated epithelium (FAE)
Epithelium overlying single or aggregated lymphoid follicles
that facilitate transcytosis via the presence of M cells.
follicular B cells
Lymphoid follicle mature B cells in secondary lymphoid
tissue that are activated by Td antigens and generate memory
B cells as well as short- and long-lived plasma cells.
follicular center cell lymphoma
A mature B cell malignancy.
follicular center cells
B lymphocytes in germinal centers (secondary follicles).
Schematic representation of follicular dendritic cell.
follicular dendritic cell
Cells manifesting narrow cytoplasmic processes that interdigitate
between densely populated areas of B lymphocytes
in lymph node follicles and in spleen. Antigen–antibody
complexes adhere to the surfaces of follicular dendritic cells
and are not generally endocytosed but are associated with the
formation of germinal centers. These cells are bereft of class
II histocompatibility molecules, although Fc receptors, complement
receptor 1, and complement receptor 2 molecules
are demonstrable on their surfaces. They display antigens
on their surfaces for B cell recognition and participate in the
activation and selection of B cells expressing high-affinity
membrane immunoglobulin during affinity maturation.
follicular hyperplasia
Lymph node enlargement associated with an increase in follicle
size and number. Germinal centers are usually present