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e. 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 biological terms, the development of the human body entails growth from a one-celled ...
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 ...
Gestational age: 7 weeks and 0 days until 7 weeks and 6 days old. 50–56 days from last menstruation. Embryonic age: Week nr 6. 5 weeks old. 36–42 days from fertilization. The embryo measures 13 mm (1⁄2 in) in length. Lungs begin to form. The brain continues to develop.
Carnegie stages. In embryology, Carnegie stages are a standardized system of 23 stages used to provide a unified developmental chronology of the vertebrate embryo. The stages are delineated through the development of structures, not by size or the number of days of development, and so the chronology can vary between species, and to a certain ...
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. The resulting fusion of these two cells produces a single-celled zygote that undergoes many cell ...
e. The fetal endocrine system is one of the first systems to develop during prenatal development of a human individual. The endocrine system arises from all three embryonic germ layers. The endocrine glands that produce the steroid hormones, such as the gonads and adrenal cortex, arise from the mesoderm. In contrast, endocrine glands that arise ...
The development of the reproductive system is the part of embryonic growth that results in the sex organs and contributes to sexual differentiation. Due to its large overlap with development of the urinary system, the two systems are typically described together as the genitourinary system. The reproductive organs develop from the intermediate ...
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. Additionally, embryology encompasses the study of congenital disorders that occur before birth ...