Follicle

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Related to lymphoid follicle: lymphoid tissue, Lymph system

follicle

[′fäl·ə·kəl]
(biology)
A deep, narrow sheath or a small cavity.
(botany)
A type of dehiscent fruit composed of one carpel opening along a single suture.

Follicle

 

a dry, one-celled, many-seeded, and monocarpel-lary fruit that opens along a ventral suture. The seeds are located along the suture on the edges of the carpel. Follicles are typical of the magnolias; of such members of Ranunculaceae as cowslip, garden columbine, aconite and larkspur; and of some genera of Rosaceae, such as Physocarpus.

The simplest follicles resemble a leaf folded in half lengthwise; the upper part corresponds to a stigma and the stem to a stalk. A large number of follicles may be positioned in a spiral on the axis of a blossom (as in the magnolia) to form a multiple fruit. Other types of fruits developed from follicles: nuts are follicles with a single seed, and beans are follicles with a different form of opening.


Follicle

 

a round, oval, or pear-shaped anatomical structure present in various organs in man and other vertebrates, having varied functions. In mammals egg cells develop within the ovarian follicle, which consists of a group of cells; one of these is the egg cell and the rest are epithelial cells surrounding the egg, first in one layer and then in several. As the follicle matures, spaces between the cells become filled with a clear liquid, and the single-layered primordial follicle is transformed into a mature multi-layered follicle, the Graafian follicle.

The follicle of the thyroid gland secretes thyroglobulin, a precursor of the thyroid hormones. Into the hair follicles, which enclose the hair roots and bulbs, empty excretory ducts of the sebaceous glands. Many lymphatic follicles are located in the mucous membranes of the digestive tract, the respiratory tract, and the urinary tract; for instance, follicles known as peyer’s patches are situated in the mucous membrane layer of the intestine.

References in periodicals archive ?
In histopathologic examination, both of these disorders show marked lymphocytic infiltration but IgG4-related disease can be differentiated from SS by lymphoid follicles formation, lower lymphocytic infiltration and marked IgG4+ plasma cells infiltration (>10 IgG4+ cells/HPF) with a ratio of IgG4+ to IgG+ cells of more than 40%, which is never seen in SS.
Upon induction of an inflammatory state, FDCs and lymphoid follicles were found to arise within the collagen sponges.
Similarly, the production of CCL19 in the ileum and the rectum and that of CCL21 in the jejunum suggest that R-sIL-7gly injection also triggers T-cell migration into the lymphoid follicles of the gut, where massive T-cell proliferation subsequently occurs.
Most cases have interspersed intact or disrupted reactive lymphoid follicles.
Pattern A, which is seen in acute HIV infection, is characterized by serpiginous and greatly enlarged lymphoid follicles with reactive germinal centers (figure 1).
By light microscopy, there are conglomerates of altered regressed lymphoid follicles with hyaline germinal centers, CD21+ dendritic cell proliferations, and radially penetrating sclerotic blood vessel (so-called lollipop sign).
Histologically, the characteristic finding is the presence of uniform neoplastic lymphoid follicles packed closely together (figure, A), usually effacing the nodal architecture and often extending out into the extranodal fat (figure, B).
28) Caution, however, is required in the evaluation of immunoglobulin studies using polymerase chain reaction (PCR) techniques in fixed, paraffin-embedded tissues; small monoclonal bands may occur in extranodal reactive lymphoid hyperplasia, as for example in chronic active gastritis associated with H pylori and associated with lymphoid follicles.
Other histologic findings variably present included an interstitial pneumonia pattern at the boundary of the nodules, lymphoplasmacytic chronic bronchiolitis with associated stenosis, lymphoid follicles, prominent eosinophilic infiltration, focal areas of obstructive pneumonia, multinucleated giant cells, and focal accumulations of neutrophils.
The concept of "pseudolymphoma" for reactive localized masses of lymphoid tissue in the lung was initially proposed by Saltzstein (34) in his review of pulmonary lymphoid lesions showing low histologic grade, the presence of numerous lymphoid follicles, and a benign clinical course.
The contents of the stroma ranged from prominent lymphoid follicles with germinal centers to small focal collections of lymphocytes.