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embryo is that there is a potential for the conceptus to split into identical twins prior to implantation, and so (the argument goes) the conceptus cannot be regarded before implantation as a single human being. However, the conceptus before implantation exhibits self-actuated activity, which has led to the assertion that it is an embryo. Further, identical twinning is an instance of asexual reproduction whereby a conceptus, without ceasing to be what it is (a new human being), provides a cell or cells as a new conceptus, entirely separated or partially separated (a 'siamese' twin) from the original conceptus, but in any event self-actuated in its development from the moment that the act of asexual reproduction (twinning) is complete. By this asexual reproduction, the parents of the original conceptus in effect become grandparents to the identical twin so conceived.
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Use of the term pre-embryo, in the context of human development, has drawn criticism from opponents of embryo research. From scientists who have considered this categorization invalid or unnecessary. One rationale that has been advanced for distinguishing an early fertilized human conceptus from an
68:, though this term has not been adopted by the scientific community. A conceptus between fertilization and implantation is also frequently classified as a
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79:. Implantation begins about six days after fertilization, and lasts for about a week, during which time formation of the primitive streak occurs.
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Spallone, Patricia. “Bad
Conscience and Collective Unconscious: Science, Discourse and Reproductive Technology” in Rosenbeck, Bente et al.
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stated that a conceptus could be both a pre-implantation embryo and a pre-embryo at the same time. However,
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156:(See Hurlbut, 2005, and section III. Pluripotent Stem Cells Derived from Biological Artifacts in the PCBE's
384:“Preimplantation Genetic Diagnosis and Embryo Research-Human Developmental Biology in Clinical Practice,”
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Even after implantation begins, a pre-embryo may exist up until the formation of the
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134:(o) indicates the (natural &) standard reproductive and embryogenic pathway
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Report of the Human Embryo
Research Panel of the National Institutes of Health
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The word pre-embryo is sometimes used in ethical contexts to refer to a human
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The colors represent the maternal and paternal genetic contributions.
169:(see Charles E. Boklage, 2006, for a review on chimerism and twinning)
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142:(see Scott, 2002, Hall, 2003, for a review on monozygotic twinning)
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The illustration shows the ontological status of the preembryo,
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pages 50 and 214-215 (Oxford
University Press 1992).
16:For the stage in plant embryonic development, see
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400:Ethics of Health Care: An Introductory Textbook
318:, pages 131-132 (Museum Tusculanum Press 1995).
194:(pm) indicates a partial hydatidiform mole, and
164:(ch) indicates all the possible pathways for a
137:(mz) indicates all the possible pathways for a
402:, page 127 (Georgetown University Press 2002).
387:International Journal of Developmental Biology
347:, page 39 (Martinus Nijhoff Publishers 1996).
373:, page 31 (Cambridge University Press 1997).
256:(CM) indicates a complete hydatidiform mole,
250:(I) indicates a live born individual person.
253:(PM) indicates a partial hydatidiform mole,
191:(cm) indicates a complete hydatidiform mole
158:Report on alternative sources of stem cells
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46:Pre-embryo in human embryonic development
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23:Series of cells formed before the embryo
434:Connecticut Law Review 36 (4): 1051–93.
398:Ashley, Benedict and O’Rourke, Kevin.
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86:In the United States, a report by the
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343:Pickering, Neil and Evans, Donald.
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173:(dz) indicates the pathway of a
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316:Forplantning, køn og teknologi
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389:, volume 45, page 607 (2001).
179:(en) indicates an enucleated
88:National Institutes of Health
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334:, page 94 (Routledge 1994).
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28:human embryonic development
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371:The Embryo Research Debate
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110:status of the proembryo,
332:Ethics and Biotechnology
70:pre-implantation embryo
283:In vitro fertilization
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293:Stem cell controversy
160:for a review of ANT))
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358:“Life Before Birth,”
356:Steinbock, Bonnie.
52:Zygote § Humans
432:What is an Embryo?”
166:chimeric individual
417:2009-01-30 at the
369:Mulkay, Michael.
345:Creating the Child
150:created by either
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98:Ontological status
236:(E) indicates an
208:(O) indicates an
187:hydatidiform mole
146:(/c) indicates a
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430:Kiessling, Ann.
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259:(T) indicates a
243:(F) indicates a
229:(B) indicates a
222:(M) indicates a
215:(Z) indicates a
185:(m) indicates a
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139:monozygotic twin
77:primitive streak
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66:implantation
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40:implantation
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108:ontological
451:Embryology
231:blastocyst
50:See also:
32:pre-embryo
299:Footnotes
288:Pregnancy
58:conceptus
36:conceptus
18:Proembryo
445:Category
415:Archived
272:See also
261:teratoma
421:(1994).
154:or ANT
38:before
238:embryo
224:morula
217:zygote
210:oocyte
181:oocyte
125:, and
123:embryo
114:, and
112:embryo
245:fetus
148:clone
127:fetus
116:fetus
34:is a
152:SCNT
106:The
64:and
30:, a
26:In
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323:^
307:^
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20:.
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