Page 1539 - Veterinary Immunology, 10th Edition

VetBooks.ir Eosinophil A polymorphonuclear leukocyte containing

characteristic granules that stain intensely with the dye eosin.

Eosinophilia Increased numbers of eosinophils in the blood.

Epithelioid cells Macrophages that accumulate around a tubercle
and resemble epithelial cells in histological sections.

Epitope A site on the surface of an antigen that is recognized by an
antigen receptor. As a result, immune responses are directed

against specific epitopes. Synonymous with antigenic
determinant.

Erythema Redness due to inflammation.

Eukaryotic organism An organism characterized by cells

possessing a distinct nucleus and containing both DNA and
RNA.

Eutherians The placental mammals; the order to which humans
and domestic mammals belong.

Exocytosis The export of material from a cell by the fusion of
cytoplasmic vesicles with the outer cell membrane.

Exogenous antigen A foreign antigen that originates at a source
outside the body; for example, bacterial antigens.

Exon An expressed region within a gene.

Exotoxins Soluble protein toxins, usually produced by Gram-

positive bacteria, that have a specific toxic effect.

F

Fab fragment The antigen-binding fragment of a partially digested
antibody. It consists of a light chain and the N-terminal halves of
a heavy chain.

Facultative intracellular organism An organism that can, if
necessary, grow within cells.

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