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The theory of recapitulation, also called the biogenetic law or embryological parallelism—often expressed using Ernst Haeckel's phrase "ontogeny recapitulates phylogeny"—is an historical hypothesis that the development of the embryo of an animal, from fertilization to gestation or hatching (), goes through stages resembling or representing successive adult stages in the evolution of the ...
In social sciences, atavism is the tendency of reversion. For example, people in the modern era reverting to the ways of thinking and acting of a former time. The word atavism is derived from the Latin atavus —a great-great-great-grandfather or, more generally, an ancestor.
Parthenogenesis ( / ˌpɑːrθɪnoʊˈdʒɛnɪsɪs, - θɪnə -/; [1] [2] from the Greek παρθένος, parthénos, 'virgin' + γένεσις, génesis, 'creation' [3] ) is a natural form of asexual reproduction in which growth and development of an embryo occur directly from an egg, without need for fertilization.
Embryo. 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 ...
Abortion is the termination of a pregnancy by removal or expulsion of an embryo or fetus. [ nb 1] An abortion that occurs without intervention is known as a miscarriage or "spontaneous abortion"; these occur in approximately 30% to 40% of all pregnancies. [ 2][ 3] When deliberate steps are taken to end a pregnancy, it is called an induced ...
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.
Pregnancy test. A pregnancy test is used to determine whether a female is pregnant or not. The two primary methods are testing for the female pregnancy hormone ( human chorionic gonadotropin (hCG)) in blood or urine using a pregnancy test kit, and scanning with ultrasonography. [1] Testing blood for hCG results in the earliest detection of ...
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 ...