germinal centers

(noun)

Places within secondary lymph nodes to which B cells migrate to proliferate and differentiate based on an antigen response.

Related Terms

Examples of germinal centers in the following topics:

  • Lymphoid Tissue

    • During antigen presentation, such as from the dendritic cells, lymphocytes migrate to germinal centers of the secondary lymphoid tissues, where they undergo clonal expansion and affinity maturation.

  • Tonsils

    • Captured antigens are presented to B and T cells within the tonsil, then the B cells migrate to germinal centers within the tonsil as an adaptive immune response is initiated.

  • Lymph Transport

    • When a lymphocyte is presented with an antigen (such as by an activated helper T cell), B cells become activated and migrate to the germinal centers of the node, where they proliferate and differentiate to be specific to that antigen.
    • Four pairs of lymph trunks are distributed laterally around the center of the body, along with an unpaired intestinal trunk.

  • Clonal Selection and B-Cell Differentiation

    • After activation, the B cell will then undergo differentiation and clonal expansion, which usually involves migrating to germinal centers should the activation take place in a lymph node.

  • Maturation of B Cells

    • The B cell may either become one of these cell types directly or it may undergo an intermediate differentiation step, the germinal center reaction, where the B cell will hypermutate the variable region of its immunoglobulin gene ("somatic hypermutation") and possibly undergo class switching.

  • Lymph Nodes

    • Inside each sinus cavity is a nodule, a smaller, denser bundle of lymphoid tissue that usually contains a germinal center, the site of B cell proliferation during antigen presentation.

  • Lymphocytes

    • After antigen presentation, the naive B cells migrate together to germinal centers within the lymphoid tissue, where they undergo extensive proliferation and differentiation into different types of mature B cells.

  • Nails

    • The root of the fingernail is also known as the germinal matrix.
    • The edge of the germinal matrix is seen as a white, crescent shaped structure called the lunula.
    • It extends from the edge of the germinal matrix, or lunula, to the hyponychium.

  • Role of the Cardiovascular Center

    • Located in the medulla oblongata, the cardiovascular center  contains three distinct components: the cardioaccelerator center, the cardioinhibitor center, and the vasomotor center.
    • The vasomotor center controls vessel tone or contraction of the smooth muscle in the tunica media.
    • Although each center functions independently, they are not anatomically distinct.
    • The cardiovascular center can respond to numerous stimuli.
    • Explain the role of the cardiovascular center in controlling blood pressure

  • Testicular Cancer

    • Testicular seminoma originates in the germinal epithelium of the seminiferous tubules.