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Evolutionary embryology is the expansion of comparative embryology by the ideas of Charles Darwin. Similarly to Karl Ernst von Baer 's principles that explained why many species often appear similar to one another in early developmental stages, Darwin argued that the relationship between groups can be determined based upon common embryonic and ...
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 .
An embryo is the initial stage of development for a multicellular organism.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.
Morphogenesis is important for creating the three germ layers of the early embryo (ectoderm, mesoderm, and endoderm) and for building up complex structures during organ development. Tissue growth involves both an overall increase in tissue size, and also the differential growth of parts ( allometry ) which contributes to morphogenesis.
Development of the human body is the process of growth to maturity.The process begins with fertilization, where an egg released from the ovary of a female is penetrated by a sperm cell from a male.
Prenatal development (from Latin natalis 'relating to birth') involves the development of the embryo and of the fetus during a viviparous animal's gestation.Prenatal development starts with fertilization, in the germinal stage of embryonic development, and continues in fetal development until birth.
Gould laid to rest Haeckel's interpretation of evolutionary embryology, while Jacob set out an alternative theory. [10] This led to a second synthesis, [29] [30] at last including embryology as well as molecular genetics, phylogeny, and evolutionary biology to form evo-devo.
Comparative vertebrate embryology. The embryonic disc becomes oval and then pear-shaped, the wider end being directed forward. Towards the narrow, posterior end, an opaque primitive streak , is formed and extends along the middle of the disc for about half of its length; at the anterior end of the streak there is a knob-like thickening termed ...