monocyte

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monocyte

 [mon´o-sīt]
a mononuclear, phagocytic leukocyte, 13 μm to 25 μm in diameter, having an ovoid or kidney-shaped nucleus and azurophilic cytoplasmic granules. Monocytes are derived from promonocytes in the bone marrow and circulate in the blood for about 24 hours before migrating to the tissues, such as the lung and liver, where they develop into macrophages. adj., adj monocyt´ic.

mon·o·cyte

(mon'ō-sīt),
A relatively large mononuclear leukocyte (16-22 mcm in diameter) that normally constitutes 3-7% of the leukocytes of the circulating blood and is normally found in lymph nodes, spleen, bone marrow, and loose connective tissue. When treated with the usual dyes, monocytes manifest an abundant pale blue or blue-gray cytoplasm that contains numerous fine, dustlike, red-blue granules; vacuoles are frequently present; the nucleus is usually indented, or slightly folded, and has a stringy chromatin structure that seems more condensed where the delicate strands are in contact. Monocytes that leave the bloodstream and enter the connective tissue spaces are called macrophages.
See also: monocytoid cell, endothelial leukocyte.
[mono- + G. kytos, cell]

monocyte

(mŏn′ə-sīt′)
n.
A large, circulating, phagocytic white blood cell, having a single well-defined nucleus and very fine granulation in the cytoplasm. Monocytes constitute from 3 to 8 percent of the white blood cells in humans.

mon′o·cyt′ic (-sĭt′ĭk), mon′o·cy′toid′ (-sī′toid′) adj.

monocyte

Hematology A phagocytic WBC that arises in BM from a common progenitor, CFU-GM; 'daughter' monocytes circulate in the blood, forming resident and transient populations in various sites; resident monocytes–histiocytes include Kupffer cells–liver, Langerhans cells–dermis, microglial cells–brain, pleural, peritoneal, alveolar macrophages and osteoclasts; monocytes normally constitute 2%–8% of peripheral WMCs, measure 12-25 µm, have a reniform nucleus with lacy chromatin, an N:C ratio of 4:1 to 2:1, and gray blue cytoplasm containing lysosomal enzymes–eg, acid phos, arginase, cathepsins, collagenases, deoxyribonuclease, lipases, glycosidases, plasminogen activator and others, and surface receptors–eg, FcIgG and C3R; monocytes are less efficient in phagocytosis than PMNs, but have a critical role in antigen processing. See CFU-GM, White blood cell.

mon·o·cyte

(mon'ō-sīt)
A relatively large mononuclear leukocyte (16-22 mcm in diameter); monocytes normally constitute 3-7% of the leukocytes of the circulating blood; normally found in lymph nodes, spleen, bone marrow, and loose connective tissue. In stained smears, monocytes have abundant pale blue or blue-gray cytoplasm that contains numerous fine red-blue granules and vacuoles; the nucleus is usually indented, or slightly folded.
[mono- + G. kytos, cell]
Enlarge picture
MONOCYTES: (Orig. mag. ×640)

monocyte

(mon'o-sit?) [ mono- + -cyte],

MO

A mononuclear phagocytic white blood cell derived from myeloid stem cells. Monocytes circulate in the bloodstream for about 24 hr and then move into tissues, at which point they mature into macrophages, which are long lived. Monocytes and macrophages are one of the first lines of defense in the inflammatory process. This network of fixed and mobile phagocytes that engulf foreign antigens and cell debris previously was called the reticuloendothelial system and is now referred to as the mononuclear phagocyte system (MPS).
See: illustration; blood for illus.; macrophagemonocytic (mon-o-sit'ik), adjectiveillustration

monocyte

A large white blood cell with a round or kidney-shaped nucleus. There are no granules in the CYTOPLASM. The monocyte migrates to the tissues where it becomes a MACROPHAGE.

monocyte

or

macrocyte

a type of LEUCOCYTE (white blood cell) of the AGRANULOCYTE group that is produced from stem cells in the bone marrow and is 12–15 μm in diameter. Monocytes remain in the blood for a short time and then migrate to other tissues as MACROPHAGES, moving particularly to those areas invaded by bacteria and other foreign materials where they ingest large particles by PHAGOCYTOSIS. See also HISTOCYTE, LYMPHOCYTE.

Monocyte

White blood cell that increases during a variety of conditions including severe infections. It removes debris and microorganisms by phagocytosis.

mon·o·cyte

(mon'ō-sīt)
A relatively large mononuclear leukocyte that normally constitutes 3-7% of the leukocytes in circulating blood.
[mono- + G. kytos, cell]
References in periodicals archive ?
Hutchison, "Extranodal monocytoid B-cell lymphoma of the urinary bladder," Modern Pathology, vol.
C and D, Cytology of MALT lymphoma can range from small lymphocytic morphology (C) to monocytoid morphology (D) (hematoxylin- eosin, original magnifications X20 [A], X200 [B], and X400 [C and D]).
Frequency of bcl-2 expression in non-Hodgkin's lymphoma: a study of 778 cases with comparison of marginal zone lymphoma and monocytoid B-cell hyperplasia.
Age, Site(s) Original Morphology y/Sex Diagnosis 1 68/F Neck LN LPL Small lymphocytes, plasmacytoid lymphocytes, and plasma cells with Dutcher bodies;many admixed, larger cells with pleomorphic nuclei;no sheets of large cells 2 88/M Bone marrow LPL Almost exclusively plasma-cell infiltrate, interstitial pattern 3 76/M Bone marrow LPL Plasmacytoid lymphocytes and plasma cells, nodular and interstitial pattern 4 62/F Bilateral MZL Small lymphocytes, orbital masses some monocytoid morphology;no plasmacytoid or plasma-cell component; prominent follicular colonization 5 65/M Salivary gland, MZL Small lymphocytes submandibular LN, with minor subsets inguinal LN showing monocytoid or minimally plasmacytoid morphology; scattered, admixed plasma cells Case No.
A, Note the expanded follicles with a nodular proliferation of intermediate-sized cells with monocytoid appearance and lymphoplasmacytoid differentiation.
The reactive lymphoid follicles comprise germinal centers with polarity and tingible-body macrophages, and the germinal centers are surrounded by the mantle zone with small mantle cells; the marginal zone with monocytoid lymphocytes is located outside of the mantle zone in the parafollicular area and is usually not prominent in the lymph nodes.
Cytologically, the neoplastic lymphocytes in PCMZL include variable combinations of centrocyte-like (marginal zone) B cells; lymphocytes with relatively abundant, pale cytoplasm, imparting a monocytoid appearance (monocytoid B cells); and cells with plasmacytic differentiation.
Nodular aggregates of monocytoid lymphocyte without secondary germinal centers were scattered throughout the lesion.
Most lymphocytes are small with monocytoid, centroblastic, or immunoblastic lymphocytes comprising only a small subset of the neoplastic cells.
The signet ring cells within these tumors can demonstrate a plasmacytoid or monocytoid appearance or can have the classic signet ring cell morphology, characterized by a large cytoplasmic vacuole compressing the nucleus to one side of the cell.
(18,21,28) Usually, prominent, sinusoidal monocytoid B-cell hyperplasia is present; neutrophils are often also seen within the sinuses.
The neoplastic cells are morphologically described as showing a spectrum of monocytoid, centrocyte-like, or lymphoplasmacytic cytology and occasionally appearing as large transformed B lymphocytes.