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Human embryonic development or human embryogenesis is the development and formation of the human embryo.It is characterised by the processes of cell division and cellular differentiation of the embryo that occurs during the early stages of development.
Humans are bilateral animals that have holoblastic rotational cleavage. Humans are also deuterostomes. In regard to humans, the term embryo refers to the ball of dividing cells from the moment the zygote implants itself in the uterus wall until the end of the eighth week after conception. Beyond the eighth week after conception (tenth week of ...
These cell divisions are usually rapid with no growth so the daughter cells are half the size of the mother cell and the whole embryo stays about the same size. They are called cleavage divisions. Mouse epiblast primordial germ cells (see Figure: "The initial stages of human embryogenesis ") undergo extensive epigenetic reprogramming. [ 16 ]
The cells of the inner cell mass (embryoblast), which are known as human embryonic stem cells (hESCs), will further differentiate to form four structures: the amnion, the yolk sac, the allantois, and the embryo itself. Human embryonic stem cells are pluripotent, that is, they can differentiate into any of the cell types present in the adult ...
In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm cell. The resulting fusion of these two cells produces a single-celled zygote that undergoes many cell divisions that produce cells known as blastomeres .
Embryonic stem cells is one of the sources that are being considered for the use of tissue engineering. [19] The use of human embryonic stem cells have opened many new possibilities for tissue engineering, however, there are many hurdles that must be made before human embryonic stem cell can even be utilized.
List of human cell types derived from the germ layers. ... Related changes; Upload file ... This is a list of cells in humans derived from the three embryonic germ ...
Two of Haeckel's other ideas about the evolution of development have fared better than recapitulation: he argued in the 1870s that changes in the timing (heterochrony) and changes in the positioning within the body of aspects of embryonic development would drive evolution by changing the shape of a descendant's body compared to an ancestor's ...