Page 1554 - Veterinary Immunology, 10th Edition

complexes.
VetBooks.ir Orthologous Genes that are clearly descended from a common

ancestral gene.

Osteichthyes The class containing the bony fish. It includes several

orders of fish, the most highly evolved of which are the teleosts.
The teleosts include such typical fish as the goldfish, catfish, and
trout.

P

Paracortex The region located between the cortex and medulla of
lymph nodes in which T cells predominate.

Paralogous Two genes or gene clusters that, although likely
descended from a single ancestor, are located on different

chromosomes and have diverged significantly.

Parasite An organism that lives on or in a host animal and

consumes resources of host origin.

Passive agglutination The agglutination of inert particles by

antibody directed against antigen bound to their surface.

Passive immunization Protection of one individual conferred by

administration of antibody produced in another individual.

Pathobiont A member of the normal microbiota that has the ability

to become a pathogen.

Pathogen-associated molecular patterns (PAMPs) Conserved

molecular structures widely distributed among pathogenic
microbes that trigger inflammation.

Pathogenesis The mechanism of a disease.

Pathogenic organism (Pathogen) An organism that causes disease.

Pattern-recognition receptors (PRRs) Cellular receptors that can
recognize pathogens or their soluble components. PRRs include

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