Organogenesis, also known as organogenesis, generally refers to the process by which an organ's primordium evolves into an organ during vertebrate development. The formation of various organs is early and late. Through the organogenesis stage, various organs undergo morphogenesis and tissue differentiation, and gradually obtain specific forms and perform certain physiological functions.
Organogenesis is the process of development of three germ layers of internal organs consisting of ectoderm (external), mesoderm (middle) and endoderm (inner).Through morphogenesis, the cells of each germ layer establish a certain spatial relationship to organogenesis, which lays the basic pattern of embryos. The basic pattern of the vertebrate embryos is roughly the same, that is, the mesoderm is the central axis, the dorsal is the neural tube from the ectoderm, the ventral is the primitive intestine from the endoderm, and the sides are the predetermined segments and sides. In the mesoderm, the epidermis from the ectoderm covers the entire embryo. In later development, the cells of the three germ layers form various organ primordia and develop into adult organs through tissue differentiation.
Process of organogenesis
The primordial limbs are called wing buds and leg buds, respectively. Take the wing bud as an example, this is on the front side of the embryo body. A pair of bulges formed at the same time. Each ridge structure is very simple, consisting of a thin layer of epidermis covering a group of undifferentiated mesenchymal cells from the mesoderm. The epidermis forms a thickened band at the top of the bud, called the apical epidermis, and the underlying mesenchymal cells remain undifferentiated, called the developmental zone, thereby gradually producing limbs from the proximal to the distal side. Various parts. The mesenchymal cells in the proximal part are assembled to form the precursor of the bone components of the forelimb. After 3 days, the dyed cartilage dye has been used to dye the entire skeleton, and by the 6th day the bones are very clear. The muscles in the forelimbs are formed by somite cells that migrate into the limb buds. By the 9th day and a half, the shape of the wing is close to the adult. Although the wings and legs are composed of a few types of cells, such as muscle, cartilage, hard bone, and loose connective tissue, these cells are arranged differently in space, resulting in a unique pattern of wings and legs.
Mechanism of organ formation
Scientists have found that without the interaction of cells from other tissues, the germ layer cannot form its own organs. In humans, internal organs after fertilization begin to develop. The germ layer forms organs through three processes: folding, splitting, and coagulation. Wrinkles are formed in the germinal layer of the cell and usually form a closed tube that can be seen in the development of the vertebrate neural tube. A gap or pocket may form on the germinal cell sheet to form a vesicle or elongation. The lungs and glands of the organism may develop in this manner. The first step in the development of the chordate is the development of the notochord, which induces the formation of the neural plate and ultimately leads to the formation of neural tubes in the development of the vertebrate. The development of the neural tube will cause the growth of the brain and spinal cord. Vertebrates form nerve c, which differentiates into many structures, including bones, muscles, and components of the central nervous system. The differentiation of the ectoderm into the nerve, the neural tube and the surface ectoderm is sometimes called nerve, and the embryo at this stage is the nerve. The body cavity of the body is formed by the division of mesoderm along the torso axis.