granule cells

Examples of granule cells in the following topics:

• Parts of the Cerebellum

  • This thin layer contains several types of neurons with a highly regular arrangement, most importantly Purkinje cells and granule cells .
  • Due to its large number of tiny granule cells, the cerebellum contains more neurons than the rest of the brain put together, but comprises only 10% of total brain volume.
  • Transverse section of a cerebellar folium, showing principal cell types and connections.

• Natural Killer Cells

  • NK cells provide rapid responses to virus-infected cells and respond to tumor formation by destroying abnormal and infected cells.
  • NK cells use wo cytolytic granule-mediated apoptosis to destroy abnormal and infected cells.
  • The granules of NK cells contain proteins such as perforin and proteases known as granzymes.
  • Virus-infected cells destroyed by cell lysis release their replicated virus particles into the body, which infects other cells.
  • Antibodies that bind to antigens can be recognized by FcϒRIII (CD16) receptors (a type of activating receptor), resulting in NK activation, release of cytolytic granules, and consequent cell apoptosis.

• Types of WBCs

  • A major distinguishing feature is the presence of granules; white blood cells are often characterized as granulocytes or agranulocytes.
  • These granules are membrane-bound enzymes that act primarily in the digestion of endocytosed particles.
  • They may also cause granule dependent cell-mediated apoptosis through the release of perforins, granzymes, and proteases.
  • The cells include:
  • Monocytes and their progeny contain toll-like receptors and granules.

• Lymphoid Cells

  • The three major types of lymphocyte are T cells, B cells, and natural killer cells.
  • Activated NK cells release cytotoxic (cell-killing) granules that contain perforin and granzyme, which can lyse (break down) cell membranes and induce apoptosis to kill infected or abnormal cells.
  • If cancer cells evade NK cell detection for long enough, however, they can grow into tumors that are more resistant to NK cell activity.
  • T cells are involved in cell-mediated immunity whereas B cells are primarily responsible for humoral immunity.
  • There are two types of T cells involved in adaptive, cell-mediated immunity.

• Female Duct System

  • There are two types of cells within the simple columnar epithelium of the Fallopian tube.
  • Ciliated cells predominate throughout the tube, but are most numerous in the infundibulum and ampulla.
  • Estrogen increases the production of cilia on these cells.
  • Interspersed between the ciliated cells are peg cells, which contain apical granules and produce the tubular fluid.
  • Progesterone increases the number of peg cells, while estrogen increases their height and secretory activity.

• Types of Adaptive Immunity

  • Cell mediated immunity is controlled by type 1 helper T cells (Th1) and cytotoxic T cells.
  • Helper T cells facilitate the immune response by guiding cytotoxic T cells to pathogens or pathogen-infected cells, which they will then destroy.
  • Cytotoxic T cells kill pathogens in several ways, including the release of granules that contain the cytotoxins perforin and granzyme, which lyse small pores in the membrane of a pathogen.
  • Then T-cell produced proteases enter the pathogen and induce an apoptosis response within the cell.
  • This diagram of adaptive immunity indicates the flow from antigen to APC, MHC2, CD4+, T helper cells, B cells, antibodies, macrophages, and killer T cells.

• Overview of the Endocrine System

  • Endocrine glands are typically well vascularized and the cells comprising the tissue are typically rich in intracellular vacuoles or granules that store hormones prior to release.
  • Additionally the endocrine system is differentiated from shorter distance signaling such as autocrine (a cell affecting itself), juxtacrine (a cell affecting it's direct neighbors), and paracrine (a cell affecting other nearby cells) signaling.

• Phagocytes

  • Oxidative stress can kill a cell through DNA, cell membrane, or mitochondrial damage.
  • The main types of phagocytes are monocytes, macrophages, neutrophils, tissue dendritic cells, and mast cells.
  • Mature monocytes have large, smooth, lobed nuclei and an abundant cytoplasm that contains granules, but are not technically considered granulocytes.
  • Macrophages do not have granules, but contain many lysosomes.
  • In addition to these functions, mast cells produce cytokines kept in their granules, such as histamine,  that induce an inflammatory response when a pathogen is detected.

• WBC Function

  • This process is performed primarily by mast cells, eosinophils, basophils, and NK cells.
  • When pathogens are encountered, granule dependent apoptosis (a mechanism of cytotoxicity) may be induced in the pathogen by releasing perforins, granzymes, and proteaseases from their granules.
  • Cell mediated activities.
  • This process is performed by T cells.
  • Memory cell activity.

• Characteristics of Nervous Tissue

  • It consists of neurons and supporting cells called neuroglia.
  • The cell body is like a factory for the neuron.
  • It produces all the proteins and contains specialized organelles such as nucleus, granules and Nissl bodies.
  • In the peripheral nervous system, Schwann cells are neuroglia cells that support neuronal function by increasing the speed of  impulse propagation.
  • The Schwann cells are underlain by the medullary sheath.