Cryoelectron microscopy allows examination of hydrated, unfixed, and unstained specimens in the TEM by maintaining them at -196oC (liquid nitrogen).

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#Id: 9936

#Unit 4. Cell Communication and Cell Signaling

Extracellular Bacteria

TLS Online TPP Program

#Id: 9937

#Unit 4. Cell Communication and Cell Signaling

Intracellular bacterial

Intracellular bacterial infections tend to induce a cell-mediated immune response, specifically DTH. 

In this response, cytokines secreted by CD4+ T cells are important—most notably IFN-ϒ, which activates macrophages.

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#Id: 9938

#Unit 4. Cell Communication and Cell Signaling

Host immune responses and bacterial evasion mechanisms

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#Id: 9939

#Unit 4. Cell Communication and Cell Signaling

Tuberculosis

Tuberculosis, caused by Mycobacterium tuberculosis.

Pulmonary infection usually results from inhalation of small droplets of respiratory secretions containing a few bacilli.

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#Id: 9940

#Unit 4. Cell Communication and Cell Signaling

The inhaled bacilli are ingested by alveolar macrophages in the lung and inhibiting formation of phagolysosomes

CD4+ T cells are activated within 2 to 6 weeks after infection.

TLS Online TPP Program

#Id: 9941

#Unit 4. Cell Communication and Cell Signaling

These cells wall off the organism inside a granuloma called a tubercle. The localized concentrations of lysosomal enzymes in these granulomas can cause extensive tissue necrosis.