sertoli cells

Examples of sertoli cells in the following topics:

• Hormonal Regulation of the Male Reproductive System

  • The Sertoli cells themselves mediate parts of spermatogenesis through hormone production.
  • The Leydig cells are also capable of producing estradiol in addition to their main product, testosterone.
  • Follicle-stimulating hormone stimulates both the production of androgen-binding protein by Sertoli cells and the formation of the blood-testis barrier.
  • Testosterone is made in the interstitial cells of the testes.
  • Inhibin is secreted by the Sertoli cells and acts to decrease the levels of FSH.

• Testes Ducts

  • The epithelium of the tubule consists of tall, columnar cells called Sertoli cells.
  • Between the Sertoli cells are spermatogenic cells, which differentiate through meiosis to become sperm cells.
  • The ductuli are unilaminar and composed of columnar ciliated and nonciliated (absorptive) cells.
  • The ciliated cells stir the luminal fluids, which may help ensure homogeneous absorption of water from the fluid produced by the testis.

• Spermatogenesis

  • Spermatogenesis is the process by which male primary sperm cells undergo meiosis and produce a number of cells calls spermatogonia, from which the primary spermatocytes are derived.
  • These develop into mature spermatozoa, also known as sperm cells.
  • The non-motile spermatozoa are transported to the epididymis in testicular fluid secreted by the Sertoli cells with the aid of peristaltic contraction.
  • The excess cytoplasm, known as residual bodies, is phagocytosed by surrounding Sertoli cells in the testes.
  • The mature spermatozoa are released from the protective Sertoli cells into the lumen of the seminiferous tubule in a process called spermiation.

• Testes

  • These are lined with a layer of germ cells that develop into sperm cells (also known as spermatozoa or male gametes) from puberty into old age.
  • The developing sperm travels through the seminiferous tubules to the rete testis located in the mediastinum testis, to the efferent ducts, and then to the epididymis where newly-created sperm cells mature.
  • Leydig cells located between seminiferous tubules produce and secrete testosterone and other androgens important for sexual development and puberty, including secondary sexual characteristics such as facial hair and sexual behavior.
  • The sertoli cells are the testes’ somatic cells, necessary for testis development and spermatogenesis.

• Testicular Cancer

  • Although testicular cancer can be derived from any cell type found in the testicles, more than 95% of testicular cancers are germ cell tumors .
  • Most of the remaining 5% are sex cord-gonadal stromal tumors derived from Leydig cells or Sertoli cells.
  • Most testicular germ cell tumors have too many chromosomes, and most often they are triploid to tetraploid.
  • About half of germ cell tumors of the testis are seminomas.

• Semen

  • Sertoli cells, which nurture and support developing spermatocytes, secrete a fluid into seminiferous tubules that helps transport sperm to the genital ducts.
  • The ductuli efferentes possess cuboidal cells with microvilli and lysosomal granules that modify the semen by reabsorbing some fluid.
  • Once the semen enters the ductus epididymis, the principal cells (which contain pinocytotic vessels indicating fluid reabsorption) secrete glycerophosphocholine, which most likely inhibits premature capacitation.
  • The normal environment of the vagina is a hostile one for sperm cells, as it is acidic (from the native microflora producing lactic acid), viscous, and patrolled by immune cells.

• Specific T-Cell Roles

  • T helper cells assist the maturation of B cells and memory B cells while activating cytotoxic T cells and macrophages.
  • Differentiation into helper T cell subtypes occurs during clonal selection following T cell activation of naive T cells.
  • Cytotoxic T cells (TC cells, or CTLs) destroy virus-infected cells and tumor cells, and cause much of the damage in in transplant rejection and autoimmune diseases.
  • Memory T cells comprise two subtypes: central memory T cells (TCM cells) and effector memory T cells (TEM cells), which have different properties and release different cytokines.
  • Regulatory T cells (Treg cells), also known as suppressor T cells, are crucial for the maintenance of immunological tolerance.

• Natural Killer Cells

  • The role of NK cells is similar to that of cytotoxic T cells in the adaptive immune response.
  • 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.
  • Virus-infected cells destroyed by cell lysis release their replicated virus particles into the body, which infects other cells.
  • Cells that are osponized with antibodies are easier for NK cells to detect and destroy.

• Lymphoid Cells

  • The three major types of lymphocyte are T cells, B cells, and natural killer 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.
  • Following activation, B cells and T cells leave a lasting legacy of the antigens they have encountered in the form of memory cells.

• Maturation of T Cells

  • T cells belong to a group of white blood cells known as lymphocytes and play a central role in the cell-mediated branch of the adaptive immune system.
  • They are distinguished from other lymphocytes, such as B cells and natural killer cells (NK cells), by the presence of a T cell receptor (TCR) on the cell surface.
  • T cells can be either helper T cells or cytoxic T cells based on whether they express CD4 (helper) or CD8 (cytotoxic) glycoprotein.
  • A T cell is then signaled by the thymus to become a CD4+ cell by reducing expression of its CD8 cell surface receptors.
  • The remaining cells exit the thymus as mature naive T cells.