What is formed as a defense mechanism to prevent the spread of pathogens in chronic infections?

Granulomas are a specialized form of tissue response that occurs as a defense mechanism during chronic infections. When the immune system detects persistent pathogens that it cannot eliminate, such as certain bacteria (like Mycobacterium tuberculosis) or fungi, it may form granulomas. These structures consist of a collection of macrophages that transform into epithelioid cells, often surrounded by a layer of lymphocytes and sometimes fibroblasts. This organization helps to localize and contain the infectious agents, preventing their spread to other tissues.

Granulomas serve not only to restrict the proliferation of pathogens but also to minimize damage to surrounding tissues. They are characteristic of chronic inflammatory conditions and can be observed in various diseases, including tuberculosis and sarcoidosis. This chronic response contrasts with acute inflammation, which primarily seeks to rapidly eliminate pathogens and repair tissues, rather than containing infections that have persisted for a longer duration.

In contrast, the other options listed do not specifically serve this purpose in the context of chronic infections. Cysts are typically fluid-filled sacs that can arise from various conditions but are not directly related to the inflammatory response against pathogens. Fibroids are non-cancerous tumors that typically occur in the uterus and are unrelated to infectious processes. Membranes may form