embryonic disk

Examples of embryonic disk in the following topics:

• Amnion Development

  • Its floor consists of the prismatic ectoderm of the embryonic disk.
  • The continuity between the roof and the floor is established at the margin of the embryonic disk.
  • This fluid increases in quantity, causing the amnion to expand and ultimately to adhere to the inner surface of the chorion so that the extra-embryonic part of the coelom is obliterated.

• Bilaminar Embryonic Disc Development

  • The floor of the amniotic cavity is formed by the embryonic disc.
  • The floor of the amniotic cavity is formed by the embryonic disc, which is composed of a layer of prismatic cells and the embryonic ectoderm.
  • In humans, the formation of the embryonic disc occurs after implantation and prior to embryonic folding (between about day 14 to day 21 post-fertilization).
  • The embryonic disc forms during early development.
  • Simultaneously, morphological changes ocur in the embryoblast that result in the formation of a flat, almost circular bilaminar plate of cells--the embryonic disk--which includes the epiblast and the hypoblast.

• Blastocyst Formation

  • The blastocyst forms early in embryonic development and has two layers that form the embryo and placenta.
  • The embryoblast is the source of embryonic stem cells and gives rise to all later structures of the adult organism.
  • The floor of this cavity is formed by the embryonic disk, which is composed of a layer of prismatic cells called the embryonic ectoderm.

• Development of the Extraembryonic Coelom

  • The extra-embryonic coelom is a cavity that contains the chorion.
  • As development progresses, small lacunae begin to form within the extra-embryonic mesoderm that become larger and form the extra-embryonic coelom.
  • The extra-embryonic mesoderm is divided into two layers: the extra-embryonic splanchnopleuric mesoderm, which lies adjacent to Heuser's membrane around the outside of the primitive yolk sac; and the extra-embryonic somatopleuric mesoderm, which lies adjacent to the cytotrophoblast layer of the embryo.
  • The extra-embryonic coelomic cavity is also called the chorionic cavity—it is enclosed by the chorionic plate.
  • It consists of an extra-embryonic mesoderm and two layers of trophoblast and surrounds the embryo and other membranes.

• Development of Nervous Tissue

  • In vertebrates, landmarks of embryonic neural development include the birth and differentiation of neurons from stem cell precursors, the migration of immature neurons from their birthplaces in the embryo to their final positions, outgrowth of axons from neurons and guidance of the motile growth cone through the embryo towards postsynaptic partners, the generation of synapses between these axons and their postsynaptic partners, and finally the lifelong changes in synapses which are thought to underlie learning and memory.
  • The gastrula has the shape of a disk with three layers of cells, an inner layer called the endoderm, which gives rise to the lining of most internal organs, a middle layer called the mesoderm, which gives rise to the bones and muscles, and an outer layer called the ectoderm, which gives rise to the skin and nervous system.

• Fourth Week of Development

  • Trophoblast cells surrounding the embryonic cells proliferate and invade deeper into the uterine lining.
  • They will eventually form the placenta and embryonic membranes.
  • The embryonic heart attains functionality and starts beating at 22 days after conception (about five weeks after the last menstrual period).
  • It can sometimes be seen as flickering in the embryonic chest by an ultrasound performed during the fourth week after conception.

• Muscle Development

  • Myogenesis is the formation of muscle tissue during embryonic development from stem cells in the mesoderm.
  • Myogenesis is the formation of muscular tissue, particularly during embryonic development.
  • In early embryonic development, these myoblasts proliferate if enough fibroblast growth factor (FGF) is present.
  • A myoblast is a type of embryonic progenitor cell that differentiates to form muscle cells.
  • The embryonic layer from which muscle tissues develop, including cardiac muscle, skeletal muscles cells, tubule cell of the kidney, red blood cells, and smooth muscle in gut.

• Yolk Sac Development

  • The yolk sac, situated on the ventral aspect of the embryo, is lined by extra-embryonic endoderm, outside of which is a layer of extra-embryonic mesenchyme derived from the mesoderm.
  • The yolk sac starts forming during the second week of embryonic development, at the same time of the shaping of the amniotic sac.

• Spina Bifida

  • Spina bifida is a developmental congenital disorder caused by the incomplete closing of the embryonic neural tube.
  • Spina bifida (Latin: "split spine") is a developmental congenital disorder caused by the incomplete closing of the embryonic neural tube.

• Lymphatic Tissue Development

  • Lymphatic tissue development begins by the end of the fifth week of embryonic development.
  • Lymphatic tissues begin to develop by the end of the fifth week of embryonic development.