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Showing 1-10 of 10 Resources
  • Development of the Cerebral Cortex

    Development of the Cerebral Cortex

    Animations

    (1 min 43 sec) Most of the neurons of the cerebral cortex arise from progenitor cells that undergo repeated cell division.

  • Development of the human embryonic brain

    Development of the human embryonic brain

    Animations

    (1 min 40 sec) The fetal brain grows enormously during pregnancy, both in terms of its size and the number of neurons it has.

  • Signal molecules trigger transcription factors

    Signal molecules trigger transcription factors

    Animations

    (2 min 4 sec) Varying concentrations of a signaling molecule activate different transcription factors and determine cell fate.

  • Human Embryonic Development

    Human Embryonic Development

    Animations

    (2 min 18 sec) Human embryonic development depends on stem cells. During the course of development, cells divide, migrate, and specialize. Early in development, a group of cells called the inner cell mass (ICM) forms. These cells are able to produce all the tissues of the body. Later in development, during gastrulation, the three germ layers form, and most cells become more restricted in the types of cells that they can produce.

  • Differentiation and the Fate of Cells

    Differentiation and the Fate of Cells

    Animations

    (1 min 29 sec) As a human embryo develops, its cells become progressively restricted in the types of specialized cells that they can produce. Inner cell mass (ICM) cells of the blastocyst can make any type of body cell. Gastrula-stage cells can give rise to the cells of a given germ layer. Later, cells become even more restricted. For example, the pancreatic bud of the endoderm layer can only make the cells of the pancreas.

  • Creating Embryonic Stem Cell Lines

    Creating Embryonic Stem Cell Lines

    Animations

    (1 min 38 sec) The inner cell mass (ICM) cells of blastocyst-stage early human embryos can be removed and cultured. These cells can be grown in the lab indefinitely. Various growth factors cause these cells to develop into a variety of differentiated cells, such as muscle or nerve cells.

  • Somatic Cell Nuclear Transfer Animation

    Somatic Cell Nuclear Transfer Animation

    Animations

    (52 sec) Somatic cell nuclear transfer (SCNT) is a technique for cloning. The nucleus is removed from a healthy egg. This egg becomes the host for a nucleus that is transplanted from another cell, such as a skin cell. The resulting embryo can be used to generate embryonic stem cells with a genetic match to the nucleus donor (therapeutic cloning), or can be implanted into a surrogate mother to create a cloned individual, such as Dolly the sheep (reproductive cloning).

  • Pitx1 Expression

    Pitx1 Expression

    Animations

    (55 sec) In the stickleback fish, pelvic-fin reduction resulted from changes in the regulatory switch elements of the Pitx1 gene. In the marine ancestor, the Pitx1 gene is activated in the pelvic-fin region during development to generate the fin. In the pelvic-reduced stickleback, the regulatory switch that normally turns on the Pitx1 gene is either missing or non-functional.

  • X Inactivation

    X Inactivation

    Animations

    (55 sec) This animation shows how the random deactivation of one of the X chromosomes in a pair can lead to a mozaicism in the expression genes. 

  • Meiosis

    Meiosis

    Animations

    (5 min 53 sec) Meiosis, the form of cell division unique to egg and sperm production, sets the stage for sex determination by creating sperm that carry either an X or a Y sex chromosome. But what is it about the X or Y that determines sex? Also available in Spanish.