Leydig cell

(noun)

one of the interstitial cells, located next to the seminiferous tubules inside the testicle, that produce testosterone

Related Terms

Examples of Leydig cell in the following topics:

  • Male Hormones

    • FSH enters the testes, stimulating the Sertoli cells, which help to nourish the sperm cells that the testes produce, to begin facilitating spermatogenesis.
    • LH also enters the testes, stimulating the interstitial cells, called Leydig cells, to make and release testosterone into the testes and the blood.
    • The Sertoli cells produce the hormone inhibin, which is released into the blood when the sperm count is too high.
    • If the sperm count reaches 20 million/ml, the Sertoli cells cease the release of inhibin, allowing the sperm count to increase.

  • Hormonal Regulation of the Reproductive System

    • LH stimulates production of the sex hormones (androgens) by the Leydig cells of the testes.
    • It is also called interstitial-cell-stimulating hormone.
    • In females, FSH stimulates development of egg cells (or ova) in structures called follicles.
    • Follicle cells produce the hormone inhibin, which inhibits FSH production in the female reproductive system.
    • Oxytocin also stimulates the contraction of myoepithelial cells around the milk-producing mammary glands.

  • Male Reproductive Anatomy

    • The walls of the seminiferous tubules are composed of the developing sperm cells, with the least-developed sperm at the periphery of the tubule and the fully-developed sperm in the lumen.
    • The sperm cells are mixed with "nursemaid" cells called Sertoli cells which protect the germ cells and promote their development.
    • Other cells mixed in the wall of the tubules are the interstitial cells of Leydig; these cells produce high levels of testosterone once the male reaches adolescence.
    • Sperm consist of a flagellum (as a tail), a neck that contains the cell's energy-producing mitochondria, and a head that contains the genetic material .
    • When the sperm have developed flagella, or lash-like appendages that protrude from the cell body, and are nearly mature, they leave the testicles and enter the epididymis.

  • Cellular Differentiation

    • Three basic categories of cells make up the mammalian body: germ cells, somatic cells, and stem cells.
    • Pluripotent stem cells undergo further specialization into multipotent progenitor cells that then give rise to functional cells.
    • Hematopoietic stem cells (adult stem cells) from the bone marrow that give rise to red blood cells, white blood cells, and platelets
    • Mesenchymal stem cells (adult stem cells) from the bone marrow that give rise to stromal cells, fat cells, and types of bone cells;
    • Epithelial stem cells (progenitor cells) that give rise to the various types of skin cells

  • Gene Expression in Stem Cells

    • In mammals, there are two broad types of stem cells: embryonic stem cells, which are isolated from the inner cell mass of blastocysts, and adult stem cells, which are found in various tissues.
    • Stem cells can now be artificially grown and differentiated into specialized cell types with characteristics consistent with muscle or nerve cells through cell culture.
    • In one, the daughter cells are initially equivalent but a difference is induced by signaling between the cells, from surrounding cells, or from the precursor cell.
    • Stem cells are indicated by (A), progenitor cells by (B), and differentiated cells by (C).
    • Pluripotent, embryonic stem cells originate as inner cell mass (ICM) cells within a blastocyst.

  • Cell Theory

    • Cell theory states: living things are composed of one or more cells; the cell is the basic unit of life; cells arise from existing cells.
    • The unified cell theory states that: all living things are composed of one or more cells; the cell is the basic unit of life; and new cells arise from existing cells.
    • "All cells only arise from pre-existing cells.
    • Cells carry genetic material passed to daughter cells during cellular division
    • The cell is the basic unit of life and the study of the cell led to the development of the cell theory.

  • The Role of the Cell Cycle

    • In other words, that original single cell is the ancestor of every other cell in the body.
    • Single-celled organisms use cell division as their method of reproduction.
    • While there are a few cells in the body that do not undergo cell division, most somatic cells divide regularly.
    • A somatic cell is a general term for a body cell: all human cells, except for the cells that produce eggs and sperm (which are referred to as germ cells), are somatic cells.
    • The cell cycle is an ordered series of events involving cell growth and cell division that produces two new daughter cells.

  • Natural Killer Cells

    • After a pathogen enters the body, infected cells are identified and destroyed by natural killer (NK) cells, which are a type of lymphocyte that can kill cells infected with viruses or tumor cells (abnormal cells that uncontrollably divide and invade other tissue).
    • As such, NK cells offer a complementary check for unhealthy cells, relative to T cells.
    • NK cells are always active; an interaction with normal, intact MHC I molecules on a healthy cell disables the killing sequence, causing the NK cell to move on.
    • After the NK cell detects an infected or tumor cell, its cytoplasm secretes granules comprised of perforin: a destructive protein that creates a pore in the target cell.
    • Phagocytic cells then digest the cell debris left behind.

  • Regulation of the Cell Cycle by External Events

    • External factors can influence the cell cycle by inhibiting or initiating cell division.
    • Each cell is produced as part of its parent cell.
    • Some cells do live longer than others, but eventually all cells die when their vital functions cease.
    • Crowding of cells can also inhibit cell division.
    • Another factor that can initiate cell division is the size of the cell; as a cell grows, it becomes inefficient due to its decreasing surface-to-volume ratio.

  • Mechanics of Cellular Differentation

    • How does a complex organism such as a human develop from a single cell—a fertilized egg—into the vast array of cell types such as nerve cells, muscle cells, and epithelial cells that characterize the adult?
    • A multipotent stem cell has the potential to differentiate into different types of cells within a given cell lineage or small number of lineages, such as a red blood cell or white blood cell .
    • Finally, multipotent cells can become further specialized oligopotent cells.
    • Adult bone marrow has three distinct types of stem cells: hematopoietic stem cells, which give rise to red blood cells, white blood cells, and platelets ; endothelial stem cells, which give rise to the endothelial cell types that line blood and lymph vessels; and mesenchymal stem cells, which give rise to the different types of muscle cells.
    • The multipotent hematopoietic stem cells give rise to many different cell types, including the cells of the immune system and red blood cells.