inner cell mass

(noun)

a mass of cells within a primordial embryo that will eventually develop into the distinct form of a fetus in most eutherian mammals

Related Terms

Examples of inner cell mass in the following topics:

  • Cleavage, the Blastula Stage, and Gastrulation

    • Mammals at this stage form a structure called the blastocyst, characterized by an inner cell mass that is distinct from the surrounding blastula.
    • Here the cells in the blastula arrange themselves in two layers: the inner cell mass and an outer layer called the trophoblast .
    • The inner cell mass is also known as the embryoblast; this mass of cells will go on to form the embryo.
    • At this stage of development, the inner cell mass consists of embryonic stem cells that will differentiate into the different cell types needed by the organism.
    • The rearrangement of the cells in the mammalian blastula to two layers, the inner cell mass and the trophoblast, results in the formation of the blastocyst.

  • Cellular Differentiation

    • Three basic categories of cells make up the mammalian body: germ cells, somatic cells, and stem cells.
    • The blastocyst has an outer layer of cells, and inside this hollow sphere, there is a cluster of cells called the inner cell mass.
    • The cells of the inner cell mass go on to form virtually all of the tissues of the human body.
    • Although the cells of the inner cell mass can form virtually every type of cell found in the human body, they cannot form an organism.
    • Mesenchymal stem cells (adult stem cells) from the bone marrow that give rise to stromal cells, fat cells, and types of bone 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.

  • Comparing Plant and Animal Cells

    • Fungal and protistan cells also have cell walls.
    • Like mitochondria, chloroplasts have outer and inner membranes, but within the space enclosed by a chloroplast's inner membrane is a set of interconnected and stacked fluid-filled membrane sacs called thylakoids .
    • The fluid enclosed by the inner membrane that surrounds the grana is called the stroma.
    • The chloroplast has an outer membrane, an inner membrane, and membrane structures called thylakoids that are stacked into grana.
    • The light harvesting reactions take place in the thylakoid membranes, and the synthesis of sugar takes place in the fluid inside the inner membrane, which is called the stroma.

  • Mitochondria

    • Eukaryotic cells may contain anywhere from one to several thousand mitochondria, depending on the cell's level of energy consumption.
    • The matrix and inner membrane are rich with the enzymes necessary for aerobic respiration.
    • This organelle has an outer membrane and an inner membrane.
    • The inner membrane contains folds, called cristae, which increase its surface area.
    • ATP synthesis takes place on the inner membrane.

  • Animal Characterization Based on Features of Embryological Development

    • Radially-symmetrical animals are diploblasts, developing two germ layers: an inner layer (endoderm) and an outer layer (ectoderm).
    • Bilaterally-symmetrical animals are called triploblasts, developing three tissue layers: an inner layer (endoderm), an outer layer (ectoderm), and a middle layer (mesoderm).
    • The coelom of most protostomes is formed through a process called schizocoely, when a solid mass of the mesoderm splits apart and forms the hollow opening of the coelom.
    • Protostomes undergo spiral cleavage: the cells of one pole of the embryo are rotated and, thus, misaligned with respect to the cells of the opposite pole.
    • This characteristic of deuterostomes is reflected in the existence of familiar embryonic stem cells, which have the ability to develop into any cell type.

  • Transduction of Sound

    • The inner hair cells are the primary auditory receptors and exist in a single row, numbering approximately 3,500.
    • The stereocilia from inner hair cells extend into small dimples on the tectorial membrane’s lower surface.
    • The difference in response frequency between adjacent inner hair cells is about 0.2 percent.
    • The inner hair cells are most important for conveying auditory information to the brain.
    • About 90 percent of the afferent neurons carry information from inner hair cells, with each hair cell synapsing with 10 or so neurons.

  • Balance and Determining Equilibrium

    • With hair cells in the inner ear that sense linear and rotational motion, the vestibular system determines equilibrium and balance states.
    • Along with audition, the inner ear is responsible for encoding information about equilibrium, or the sense of balance.
    • These cells are located within the vestibule of the inner ear.
    • The macula is composed of hair cells surrounded by support cells.
    • The stereocilia of the hair cells extend into a viscous gel called the otolith.

  • Characteristics of Eukaryotic Cells

    • Like a prokaryotic cell, a eukaryotic cell has a plasma membrane, cytoplasm, and ribosomes.
    • However, unlike prokaryotic cells, eukaryotic cells have:
    • Both the inner and outer membranes of the nuclear envelope are phospholipid bilayers.
    • Animal cells have a centrosome and lysosomes, whereas plant cells do not.
    • In addition, plant cells have a cell wall, a large central vacuole, chloroplasts, and other specialized plastids, whereas animal cells do not.

  • Signaling in Yeast

    • Yeasts utilize cell-surface receptors, mating factors, and signaling cascades in order to communicate.
    • Comparisons of the genomes of yeasts, nematode worms, fruit flies, and humans illustrate the evolution of increasingly-complex signaling systems that allow for the efficient inner workings that keep humans and other complex life forms functioning correctly.
    • Budding yeasts are able to participate in a process that is similar to sexual reproduction that entails two haploid cells combining to form a diploid cell .
    • When mating factor binds to cell-surface receptors in other yeast cells that are nearby, they stop their normal growth cycles and initiate a cell signaling cascade that includes protein kinases and GTP-binding proteins that are similar to G-proteins.
    • Describe how cell signaling occurs in single-celled organisms such as yeast