Embryo - wikipedia Embryo For other uses, see Embryo ( disambiguation ). See also : Human embryogenesis and Prenatal development Embryo A human embryo, seven weeks old or from the ninth week of pregnancy. Identifiers MeSH D004622 TE E1. 0.2. 6.4. 0.8 FMA 69068 Anatomical terminology ( edit on Wikidata ) An embryo is an early stage of development of a multicellular diploid eukaryotic organism. In general, in organisms that reproduce sexually, an embryo develops from a zygote, the single cell resulting from the fertilization of the female egg cell by the male sperm cell. The zygote possesses half the DNA from each of its two parents. In plants, animals, and some protists, the zygote will begin to divide by mitosis to produce a multicellular organism. The result of this process is an embryo. In humans, a pregnancy is generally considered to be in the embryonic stage of development between the fifth and the eleventh weeks after fertilization, and is expressed as a fetus from the twelfth week. Contents 1 Etymology 2 Development 2.1 Plant embryos 3 Research and technology 3.1 Fossilized embryos 4 Miscarriage & abortion 5 See also 6 Notes 7 External links Etymology First attested in English in the mid-14c., the word embryon derives from Medieval Latin embryo, itself from Greek ἔμβρυον ( embruon ), lit. `` young one '', which is the neuter of ἔμβρυος ( embruos ), lit. `` growing in '', from ἐν ( en ), `` in '' and βρύω ( bruō ), `` swell, be full '' ; the proper Latinized form of the Greek term would be embryum. Development Play media Embryonic development of salamander, circa the 1920s. Embryos ( and one tadpole ) of the wrinkled frog ( Rana rugosa ) In animals, the development of the zygote into an embryo proceeds through specific recognizable stages of blastula, gastrula, and organogenesis. The blastula stage typically features a fluid - filled cavity, the blastocoel, surrounded by a sphere or sheet of cells, also called blastomeres. In a placental mammal, an ovum is fertilized in a fallopian tube through which it travels into the uterus. An embryo is called a fetus at a more advanced stage of development and up until birth or hatching. In humans, this is from the eleventh week of gestation. However, animals which develop in eggs outside the mother 's body, are usually referred to as embryos throughout development ; e.g. one would refer to a chick embryo, not a `` chick fetus, '' even at later stages. During gastrulation the cells of the blastula undergo coordinated processes of cell division, invasion, and / or migration to form two ( diploblastic ) or three ( triploblastic ) tissue layers. In triploblastic organisms, the three germ layers are called endoderm, ectoderm, and mesoderm. The position and arrangement of the germ layers are highly species - specific, however, depending on the type of embryo produced. In vertebrates, a special population of embryonic cells called the neural crest has been proposed as a `` fourth germ layer '', and is thought to have been an important novelty in the evolution of head structures. During organogenesis, molecular and cellular interactions between germ layers, combined with the cells ' developmental potential, or competence to respond, prompt the further differentiation of organ - specific cell types. For example, in neurogenesis, a subpopulation of ectoderm cells is set aside to become the brain, spinal cord, and peripheral nerves. Modern developmental biology is extensively probing the molecular basis for every type of organogenesis, including angiogenesis ( formation of new blood vessels from pre-existing ones ), chondrogenesis ( cartilage ), myogenesis ( muscle ), osteogenesis ( bone ), and many others. Plant embryos Further information : Sporophyte The inside of a Ginkgo seed, showing the embryo In botany, a seed plant embryo is part of a seed, consisting of precursor tissues for the leaves, stem ( see hypocotyl ), and root ( see radicle ), as well as one or more cotyledons. Once the embryo begins to germinate -- grow out from the seed -- it is called a seedling ( plantlet ). Bryophytes and ferns also produce an embryo, but do not produce seeds. In these plants, the embryo begins its existence attached to the inside of the archegonium on a parental gametophyte from which the egg cell was generated. The inner wall of the archegonium lies in close contact with the `` foot '' of the developing embryo ; this `` foot '' consists of a bulbous mass of cells at the base of the embryo which may receive nutrition from its parent gametophyte. The structure and development of the rest of the embryo varies by group of plants. Once the embryo has expanded beyond the enclosing archegonium, it is no longer termed an embryo. Research and technology Embryos are used in various fields of research and in techniques of assisted reproductive technology. An egg may be fertilized in vitro and the resulting embryo may be frozen for later use. The potential of embryonic stem cell research, reproductive cloning, and germline engineering are currently being explored. Prenatal diagnosis or preimplantation diagnosis enables testing embryos for diseases or conditions. Cryoconservation of animal genetic resources is a practice in which animal germplasms, such as embryos are collected and stored at low temperatures with the intent of conserving the genetic material. The embryos of Arabidopsis thaliana have been used as a model to understand gene activation, patterning, and organogenesis of seed plants. In regards to research using human embryos, the ethics and legalities of this application continue to be debated. Researchers from MERLN Institute and the Hubrecht Institute in the Netherlands managed to grow samples of synthetic rodent embryos, combining certain types of stem cells. This method will help scientists to more deeply study the very first moments of the process of the birth of a new life, which, in turn, can lead to the emergence of new effective methods to combat infertility and other genetic diseases. Fossilized embryos Main article : Fossil embryos Fossilized animal embryos are known from the Precambrian, and are found in great numbers during the Cambrian period. Even fossilized dinosaur embryos have been discovered. Miscarriage & abortion See also : Miscarriage and Abortion A complete spontaneous abortion at about 6 weeks from conception, i.e. 8 weeks from LMP Some embryos do not survive to the next stage of development. When this happens naturally, it is called spontaneous abortion or miscarriage. There are many reasons why this may occur. The most common natural cause of miscarriage is chromosomal abnormality in animals or genetic load in plants. In species which produce multiple embryos at the same time, miscarriage or abortion of some embryos can provide the remaining embryos with a greater share of maternal resources. This can also disturb the pregnancy, causing harm to the second embryo. Genetic strains which miscarry their embryos are the source of commercial seedless fruits. Abortion is the process of artificially ( non-naturally ) removing the embryo through deliberate pharmaceutical or surgical methods. See also In vitro fertilization Plant embryogenesis Pregnancy Prenatal development Proembryo Notes Jump up ^ `` embryo ''. Mayo. Archived from the original on 20 February 2016. Retrieved 21 February 2016. Jump up ^ ἔμβρυον Archived 2013 - 05 - 31 at the Wayback Machine., Henry George Liddell, Robert Scott, A Greek - English Lexicon, on Perseus Jump up ^ ἔμβρυος Archived 2013 - 05 - 31 at the Wayback Machine., Henry George Liddell, Robert Scott, A Greek - English Lexicon, on Perseus Jump up ^ ἐν Archived 2013 - 05 - 31 at the Wayback Machine., Henry George Liddell, Robert Scott, A Greek - English Lexicon, on Perseus Jump up ^ βρύω Archived 2013 - 05 - 31 at the Wayback Machine., Henry George Liddell, Robert Scott, A Greek - English Lexicon, on Perseus Jump up ^ Boscá, S ; Knauer, S ; Laux, T ( 2011 ). `` Embryonic development in Arabidopsis thaliana : from the zygote division to the shoot meristem ''. Frontiers in Plant Science. 2 : 93. doi : 10.3389 / fpls. 2011.00093. PMC 3355580. PMID 22639618. Jump up ^ Freedman, Jeri. `` America Debates Stem Cell Research. '' New York, NY : The Rosen Publishing Group, 2008. Jump up ^ Sandel, Michael J. `` The Case Against Perfection. '' Michael J. Sandel, 2007. Jump up ^ Zavos, Panayiotis. `` Reproductive Cloning is Moral. '' Ed. James Woodward. The Ethics of Human Cloning : At Issue. Farmington Hills, MI : Greenhaven, 2005. 14 -- 24. Jump up ^ `` Scientists grow synthetic mouse embryos from stem cells '' Archived 2018 - 05 - 08 at the Wayback Machine. New Atlas, May 4, 2018 Jump up ^ Morelle, Rebecca. `` Dinosaur embryo fossils reveal life inside the egg ''. BBC News. Archived from the original on 24 September 2015. Retrieved 8 August 2015. Jump up ^ miscarriage `` Archived copy ''. Archived from the original on 2016 - 05 - 12. Retrieved 2016 - 05 - 15. Jump up ^ Conrad Stöppler, Melissa. Shiel, Jr., William C., ed. `` Miscarriage ( Spontaneous Abortion ) ''. MedicineNet.com. Archived from the original on 2004 - 08 - 29. Retrieved 2009 - 04 - 07. Jump up ^ Kärkkäinen, Katri ; Savolainen, Outi ; Koski, Veikko ( 1999 ). `` Why do plants abort so many developing seeds : bad offspring or bad maternal genotypes ? ''. Evolutionary Ecology. 13 ( 3 ) : 305 -- 317. doi : 10.1023 / A : 1006746900736. External links Wikimedia Commons has media related to Embryology. Wikiquote has quotations related to : Embryo UNSW Embryology - Educational website A Comparative Embryology Gallery 4 - H Embryology, University of Nebraska - Lincoln Extension in Lancaster County Video with embryo of a small - spotted catshark inside the egg on YouTube Preceded by Zygote Animal development Embryo Succeeded by Fetus, Hatchling, Larva Human embryogenesis in the first three weeks Week 1 Fertilization Oocyte activation Zygote Cleavage Blastomere Morula Blastocoele Blastocyst Blastula Inner cell mass Trophoblast Week 2 ( Bilaminar ) Hypoblast Epiblast Week 3 ( Trilaminar ) Germ layers Archenteron / Primitive streak Primitive pit Primitive knot / Blastopore Primitive groove Gastrula Gastrulation Regional specification Embryonic disc Ectoderm Surface ectoderm Neuroectoderm Somatopleuric mesenchyme Neurulation Neural crest Endoderm Splanchnopleuric mesenchyme Mesoderm Axial mesoderm Paraxial Somite Somitomere Intermediate Lateral plate Intraembryonic coelom Splanchnopleuric mesenchyme Somatopleuric mesenchyme Development of the human body Before birth Development Embryo Fetus Gestational age Birth and after Birth Child development stages Puberty Adult development Ageing Senescence Death Phases Infant Toddler Early childhood Childhood Child Preadolescence Adolescence Adulthood Middle age Old age Social and legal Minor Age of majority Retrieved from `` https://en.wikipedia.org/w/index.php?title=Embryo&oldid=854388739 '' Categories : Embryology Developmental biology Hidden categories : Pages with unresolved properties Webarchive template wayback links Articles containing Ancient Greek - language text All articles with unsourced statements Articles with unsourced statements from March 2007 Articles containing video clips Talk Contents About Wikipedia Wikiquote Afrikaans ܐܪܡܝܐ Asturianu Avañe'ẽ Azərbaycanca Bân - lâm - gú Беларуская Беларуская ( тарашкевіца ) ‎ Български Bosanski Català Cebuano Čeština Dansk Deutsch Eesti Ελληνικά Español Esperanto Euskara فارسی Français Gaeilge Galego 한국어 Հայերեն हिन्दी Hrvatski Ido Bahasa Indonesia Italiano Basa Jawa ქართული Қазақша Kreyòl ayisyen Кыргызча Latina Latviešu Lëtzebuergesch Lietuvių Magyar മലയാളം मराठी Bahasa Melayu Nederlands 日本 語 Norsk Occitan ਪੰਜਾਬੀ Piemontèis Polski Português Română Русский Scots Simple English Slovenčina Slovenščina کوردی Српски / srpski Srpskohrvatski / српскохрватски Basa Sunda Suomi Svenska Tagalog தமிழ் ไทย Тоҷикӣ Türkçe Українська اردو Tiếng Việt Winaray 粵語 中文 67 more Edit links This page was last edited on 11 August 2018, at 00 : 10 ( UTC ). Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: when is the fertilized ovum considered an embryo
Answer: between the fifth and the eleventh weeks after fertilization