Early Embryonic Development

Timeline created by 21mmaslanka
  • Day 1 (Fertilization)

    Day 1 (Fertilization)
    Fertilization is the fusion of haploid gametes, egg and sperm, to form the diploid zygote. This is the beginning of embryonic development.
  • Day 8 (Implantation)

    Day 8 (Implantation)
    The process of attachment and invasion of the uterus endometrium by the blastocyst. The implantation process continues through the second week of development. The initial phase of the implantation process is "adplantation". This first phase requires the blastocyst to loosely adhere to the endometrial epithelium. This process requires both the blastocyst adhesion interaction with the endometrium during the "receptive window".
  • Day 15 (Gastrulation)

    Day 15 (Gastrulation)
    The primitive node is the small circular region located at the cranial end of the primitive streak, where gastrulation occurs, and is a controller of this process. The process establishes the 3 germ cell layers known as the Endoderm, Mesoderm and Ectoderm. The second role is to act as an initial generator of the left-right body axis.
  • Day 22 (beginning of organogenesis)

    Day 22  (beginning of organogenesis)
    Organogenesis is the formation and development of the organs of an organism from embryonic cells. The ectoderm will produce the epidermis and nervous system of the adult. The mesoderm will produce many internal organs of the adult such as the muscles, spine and circulatory system. Lastly, the endoderm will produce the digestive system and other internal organs of the adult.
  • Day 32

    Day 32
    The heart, liver, umbilical cord, mesonephric ridge become visible externally as bulges. The upper and lower limb buds are growing. There is the first appearance of the future cerebral hemispheres. Cerebellar plate is differentiated to an intermediate layer, and future rhombic lip is now identifiable.
  • Day 41

    Telencephalon areas of the future archicortex, paleocortex, and neocortex are now visible. It is the beginning of the future choroid plexus. Smell olfactory nerve fibres enter the brain. The primordium of the epidural space appears first on the ventral part of the vertebral canal and develops rostro-caudally.
  • Day 44

    Limb Bone is form by endochondrial ossification and throughout embryo replacement of cartilage with bone. There are smell vomeronasal fibres and nervus terminalis. Liver obturation due to epithelial proliferation, bile ducts became reorganized, continuity between liver cells and gut and neural System Development duramater appears.
  • Day 56

    Day 56
    Straightening of trunk, heart, liver, umbilical cord, intestines herniated at umbilicus. Upper limbs grow longer and are bent at the elbow. The hands and feet are turned inward. The foot has separated digits along with the wrist and hands.