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A fetus is a stage in the human development considered to begin nine weeks after fertilization. [4] [5] In biological terms, however, prenatal development is a continuum, with many defining features distinguishing an embryo from a fetus. A fetus is also characterized by the presence of all the major body organs, though they will not yet be ...
Human embryology is the study of this development during the first eight weeks after fertilization. The normal period of gestation (pregnancy) is about nine months or 36 weeks. The germinal stage refers to the time from fertilization through the development of the early embryo until implantation is completed in the uterus .
In human pregnancy, prenatal development is also called antenatal development. The development of the human embryo follows fertilization , and continues as fetal development . By the end of the tenth week of gestational age , the embryo has acquired its basic form and is referred to as a fetus .
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. The term can also be used to refer to the study of the entirety of an ...
Epigenetics of human development is the study of how epigenetics (hertiable characteristics that do not involve changes in DNA sequence) effects human development. Development before birth, including gametogenesis , embryogenesis , and fetal development , is the process of body development from the gametes are formed to eventually combine into ...
Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). [1] It is typical for mammals, but also occurs for some non-mammals. Mammals during pregnancy can have one or more gestations at the same time, for example in a multiple birth. [2]
Plant development is the process by which structures originate and mature as a plant grows. It is studied in plant anatomy and plant physiology as well as plant morphology. Plants constantly produce new tissues and structures throughout their life from meristems [ 35 ] located at the tips of organs, or between mature tissues.
Also called "development in context" or "human ecology" theory, ecological systems theory was originally formulated by Urie Bronfenbrenner.It specifies four types of nested environmental systems, with bi-directional influences within and between the systems; they are the microsystem, mesosystem, exosystem, and macrosystem.