"Figure 1.29: MHC I are found on all nucleated body cells, and MHC II are found on macrophages, dendritic cells, and B cells (along with MHC I). (c) Rice University. OpenStax Microbiology. CC BY 4.0. https://openstax.org/details/books/microbiology. Figure 1.30: A dendritic cell phagocytoses a bacterial cell and brings it into a phagosome. (c) Rice University. OpenStax Microbiology. CC BY 4.0. https://openstax.org/details/books/microbiology. Figure 1.31: This scanning electron micrograph shows a T lymphocyte, which is responsible for the cell-mediated immune response. Modification of work by National Cancer Institute. Public Domain. https://commons.wikimedia.org/wiki/File:Red_White_Blood_cells.jpg. Figure 1.32: (a) Red bone marrow can be found in the head of the femur (thighbone) and is also present in the flat bones of the body, such as the ilium and the scapula. Left: (c) Rice University. OpenStax Microbiology. CC BY 4.0. https://openstax.org/details/books/microbiology. Right: Stevenfruitsmaak. Public Domain. https://commons.wikimedia.org/wiki/File:Caput_femoris_cortex_medulla.jpg. Figure 1.33: The thymus is a bi-lobed, H-shaped glandular organ that is located just above the heart. Left: (c) Rice University. OpenStax Microbiology. CC BY 4.0. https://openstax.org/details/books/microbiology. Right: (c) 2012. Regents of University of Michigan Medical School. Redistribution authorized with attribution. Figure 1.34: A T-cell receptor spans the cytoplasmic membrane and projects variable binding regions into the extracellular space to bind processed antigens associated with MHC I or MHC II molecules. (c) Rice University. OpenStax Microbiology. CC BY 4.0. https://openstax.org/details/books/microbiology. Figure 1.35: This illustration depicts the activation of a naïve (unactivated) helper T cell by an antigen-presenting cell and the subsequent proliferation and differentiation of the activated T cell into different subtypes. (c) Rice University. OpenStax Microbiology. CC BY 4.0. https://openstax.org/details/books/microbiology. Figure 1.36: This figure illustrates the activation of a naïve (unactivated) cytotoxic T cell (CTL) by an antigen-presenting MHC I molecule on an infected body cell. (c) Rice University. OpenStax Microbiology. CC BY 4.0. https://openstax.org/details/books/microbiology. Figure 1.37: (a) The macrophage in this figure is presenting a foreign epitope that does not match the TCR of the T cell. Because the T cell does not recognize the epitope, it is not activated. Modification of work by (c) “Microbiotic”/YouTube. CC BY 4.0. Figure 1.38: B-cell receptors are embedded in the membranes of B cells. (c) Rice University. OpenStax Microbiology. CC BY 4.0. https://openstax.org/details/books/microbiology. Figure 1.39: T-independent antigens have repeating epitopes that can induce B cell recognition and activation without involvement from T cells. (c) Rice University. OpenStax Microbiology. CC BY 4.0. https://openstax.org/details/books/microbiology. Figure 1.40: In T cell-dependent activation of B cells, the B cell recognizes and internalizes an antigen and presents it to a helper T cell that is specific to the same antigen. (c) Rice University. OpenStax Microbiology. CC BY 4.0. https://openstax.org/details/books/microbiology."