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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.
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 .
1 - morula, 2 - blastula 1 - blastula, 2 - gastrula with blastopore; orange - ectoderm, red - endoderm. Embryology (from Greek ἔμβρυον, embryon, "the unborn, embryo"; and -λογία, -logia) is the branch of animal biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and fetuses.
It is characterised by the process of cell division and cellular differentiation of the embryo that occurs during the early stages of development. In biological terms, human development entails growth from a one-celled zygote to an adult human being. Fertilization occurs when the sperm cell successfully enters and fuses with an egg cell . [2]
Examples of neural inducers are the molecules noggin and chordin. When embryonic ectodermal cells are cultured at low density in the absence of mesodermal cells they undergo neural differentiation (express neural genes), suggesting that neural differentiation is the default fate of ectodermal cells.
Individual cells within a morphogenetic field in an embryo are flexible: thus, cells in a cardiac field can be redirected via cell-to-cell signaling to replace damaged or missing cells. [6] The Imaginal disc in larvae is an example of a discrete morphogenetic field region of cells in an insect embryo. [7]
When cells on one side of a stem grow longer and faster than cells on the other side, the stem will bend to the side of the slower growing cells as a result. This directional growth can occur via a plant's response to a particular stimulus, such as light ( phototropism ), gravity ( gravitropism ), water, ( hydrotropism ), and physical contact ...
The initial stages of human embryogenesis Parts of a human embryo. Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development [1]), usually from the time of fertilization of the egg to adult.