Preimplantation Stages of Human Development: The Biological and Moral Status of Early Embryos

Chapter

Abstract

There is currently no consensus on when human life begins, and consequently, the biological, moral, and legal status of early human embryos is unclear. Here, the biological facts concerning early human development are examined to establish a scientific view of when human life begins. The evidence clearly indicates that a new human organism (i.e., a human being) is formed at the point of sperm–egg fusion. The events occurring during preimplantation development provide further support for the conclusion that the early embryo is an organism. The status of the zygote as a complete organism is contrasted to that of human pluripotent stem cells that are best understood as parts of an organism. Two common arguments for assigning human rights to developing human beings are outlined and their logical implications are briefly discussed, in light of the scientific facts regarding human development.

Keywords

Blastocyst Conception Human rights Organism Preimplantation Zygote 

References

  1. Adjaye J et al (2005) Primary differentiation in the human blastocyst: comparative molecular portraits of inner cell mass and trophectoderm cells. Stem Cells 23(10):1514PubMedCrossRefGoogle Scholar
  2. Agar N (2007) Embryonic potential and stem cells. Bioethics 21(4):198PubMedCrossRefGoogle Scholar
  3. Anderson R, Condic ML (2008) Professor Lee Silver’s vast scientific conspiracy. First Things, http://www.firstthings.com/onthesquare/? p=946. Accessed 1 Dec 2008Google Scholar
  4. Babaie Y et al (2007) Analysis of Oct4-dependent transcriptional networks regulating self-renewal and pluripotency in human embryonic. Stem Cells 25(2):500PubMedCrossRefGoogle Scholar
  5. Boyer LA et al (2005) Core transcriptional regulatory circuitry in human embryonic stem cells. Cell 122(6):947PubMedCrossRefGoogle Scholar
  6. Burgess JA, Tawia SA (1996) When did you first begin to feel it? Locating the beginning of human consciousness. Bioethics 10(1):1–26PubMedCrossRefGoogle Scholar
  7. Byrne JA, Mitalipov SM, Wolf DP (2006) Current progress with primate embryonic stem cells. Curr Stem Cell Res Ther 1(2):127PubMedCrossRefGoogle Scholar
  8. Cauffman G et al (2009) Markers that define stemness in ESC are unable to identify the totipotent cells in human preimplantation embryos. Hum Reprod 24(1):63PubMedCrossRefGoogle Scholar
  9. Chawengsaksophak K et al (1997) Homeosis and intestinal tumours in Cdx2 mutant mice. Nature 386:84PubMedCrossRefGoogle Scholar
  10. Condic ML (2008) When does human life begin? A scientific perspective. Westchester Institute White Paper 1, no. 1: 1. Available at: www.westchesterinstitute.net. Accessed Dec 1, 2008Google Scholar
  11. Condic ML (2008b) Alternative sources of pluripotent stem cells: altered nuclear transfer. Cell Prolif 41(1):7PubMedGoogle Scholar
  12. Condic ML, Condic SB (2005) Defining organisms by organization. Natl Cathol Bioeth Q 5:331PubMedGoogle Scholar
  13. Condic ML, Rao M (2008) Regulatory issues for personalized pluripotent cells. Stem Cells 26(11):2753PubMedCrossRefGoogle Scholar
  14. Fujimori T et al (2003) Analysis of cell lineage in two- and four-cell mouse embryos. Development 130 (21):5113CrossRefGoogle Scholar
  15. Gardner RL (2001) Specification of embryonic axes begins before cleavage in normal mouse development. Development 128:839PubMedGoogle Scholar
  16. Garner E et al (2007) Gestational trophoblastic disease. Clin Obstet Gynecol 50(1):112PubMedCrossRefGoogle Scholar
  17. Gogtay N et al (2004) Dynamic mapping of human cortical development during childhood through early adulthood. Proc Natl Acad Sci USA 101(21):8174PubMedCrossRefGoogle Scholar
  18. Hamatani T et al (2004a) Global gene expression analysis identifies molecular pathways distinguishing blastocyst dormancy and activation. Proc Natl Acad Sci USA 101(28):10326PubMedCrossRefGoogle Scholar
  19. Hamatani T et al (2004b) Dynamics of global gene expression changes during mouse preimplantation development. Dev Cell 6(1):117PubMedCrossRefGoogle Scholar
  20. Hartshorn C et al (2007) Single-cell duplex RT-LATE-PCR reveals Oct4 and Xist RNA gradients in 8-cell embryos. BMC Biotechnol 7:87PubMedCrossRefGoogle Scholar
  21. Hatch O (2002) Hatch makes the case for Regenerative Medicine. Press release, 30 April 2002. http://hatch.senate.gov/newsite/index.cfm?FuseAction=PressReleases.Detail&PressRelease_id=182533&Month=4&Year=2002. Accessed 6 June 2011
  22. Hauzman EE, Papp Z (2008) Conception without the development of a human being. J Perinat Med 36(2):175PubMedCrossRefGoogle Scholar
  23. Herr JC et al (2008) Distribution of RNA binding protein MOEP19 in the oocyte cortex and early embryo indicates pre-patterning related to blastomere polarity and trophectoderm specification. Dev Biol 314(2):300PubMedCrossRefGoogle Scholar
  24. Himma KE (2003) What philosophy of mind can tell us about the morality of abortion: personhood, materialism, and the existence of self. Int J Appl Philos 17(1):89PubMedGoogle Scholar
  25. Jedrusik A et al (2008) Role of Cdx2 and cell polarity in cell allocation and specification of trophectoderm and inner cell mass in the mouse embryo. Genes Dev 22(19):2692PubMedCrossRefGoogle Scholar
  26. Kuhse H, Singer P (1988) Should the baby live?: the problem of handicapped infants. Oxford University Press, OxfordGoogle Scholar
  27. Licht P et al (2007) Is human chorionic gonadotropin directly involved in the regulation of human implantation? Mol Cell Endocrinol 269(1–2):85PubMedCrossRefGoogle Scholar
  28. Lu C-W et al (2008) Ras-MAPK signaling promotes trophectoderm formation from embryonic stem cells and mouse embryos. Nat Genet 40(7):921PubMedCrossRefGoogle Scholar
  29. Meissner A, Jaenisch R (2006) Generation of nuclear transfer-derived pluripotent ES cells from cloned Cdx2-deficient blastocysts. Nature 439(7073):212PubMedCrossRefGoogle Scholar
  30. Morgan MA et al (2008) Obstetrician-gynecologists' practices regarding preterm birth at the limit of viability. J Matern-Fetal Neonatal Med 21(2):115PubMedCrossRefGoogle Scholar
  31. Nagy A et al (1990) Embryonic stem cells alone are able to support fetal development in the mouse. Development 110(3):815Google Scholar
  32. Nishioka N et al (2008) Tead4 is required for specification of trophectoderm in pre-implantation mouse embryos. Mech Dev 125(3–4):270PubMedCrossRefGoogle Scholar
  33. Niwa H et al (2005) Interaction between Oct3/4 and Cdx2 determines trophectoderm differentiation. Cell 123(5):917CrossRefGoogle Scholar
  34. O'Sullivan CM et al (2004) Origin of the murine implantation serine proteinase subfamily. Mol Reprod Dev 69(2):126PubMedCrossRefGoogle Scholar
  35. Pearson H (2008) Making babies: the next 30 years. Nature 454(7202):260PubMedCrossRefGoogle Scholar
  36. Penner PS, Hull RT (2008) The beginning of individual human personhood. J Med Philos 32(2):174CrossRefGoogle Scholar
  37. Perona RM, Wassarman PM (1986) Mouse blastocysts hatch in vitro by using a trypsin-like proteinase associated with cells of mural trophectoderm. Dev Biol 114(1):42PubMedCrossRefGoogle Scholar
  38. Peters PG Jr (2006) The ambiguous meaning of human conception. University of California, Davis Law Review 40:199Google Scholar
  39. Piotrowska K et al (2001) Blastomeres arising from the first cleavage division have distinguishable fates in normal mouse development. Development 128:3739PubMedGoogle Scholar
  40. Piotrowska-Nitsche K et al (2005) Four-cell stage mouse blastomeres have different developmental properties. Development 132:479PubMedCrossRefGoogle Scholar
  41. Plusa B et al (2005) Downregulation of Par3 and aPKC function directs cells towards the ICM in the preimplantation mouse embryo. J Cell Sci 118(3):505PubMedCrossRefGoogle Scholar
  42. Poueymirou WT et al (2007) F0 generation mice fully derived from gene-targeted embryonic stem cells allowing immediate phenotypic analyses. Nat Biotechnol 25(1):91PubMedCrossRefGoogle Scholar
  43. Primakoff P, Myles DG (2007) Cell–cell membrane fusion during mammalian fertilization. FEBS Lett 581(11):217CrossRefGoogle Scholar
  44. Rao M, Condic ML (2008) Alternative sources of pluripotent stem cells: scientific solutions to an ethical dilemma. Stem Cells Dev 17(1):1PubMedCrossRefGoogle Scholar
  45. Rubenfeld J (1991) On the legal status of the proposition that ‘life begins at conception. Stanford Law Rev 4(3):599CrossRefGoogle Scholar
  46. Sowell ER et al (2003) Mapping cortical change across the human life span. Nat Neurosci 6(3):309PubMedCrossRefGoogle Scholar
  47. Stitzel ML, Seydoux G (2007) Regulation of the oocyte-to-zygote transition. Science 316:407PubMedCrossRefGoogle Scholar
  48. Takahashi K et al (2007) Induction of pluripotent stem cells from adult human fibroblasts by defined factors. Cell 131(5):861PubMedCrossRefGoogle Scholar
  49. Torres-Padilla M-E et al (2007) Histone arginine methylation regulates pluripotency in the early mouse embryo. Nature 445:214PubMedCrossRefGoogle Scholar
  50. Wang H et al (2008) Zonula occludens-1 (ZO-1) is involved in morula to blastocyst transformation in the mouse. Dev Biol 318(1):112PubMedCrossRefGoogle Scholar
  51. Worrad DM, Ram PT, Schultz RM (1994) Regulation of gene expression in the mouse oocyte and early preimplantation embryo: developmental changes in Sp1 and TATA box-binding protein, TBP. Development 120(8):2347PubMedGoogle Scholar
  52. Yagi R et al (2007) Transcription factor TEAD4 specifies the trophectoderm lineage at the beginning of mammalian development. Development 134(21):3827PubMedCrossRefGoogle Scholar
  53. Yu J et al (2007) Induced pluripotent stem cell lines derived from human somatic cells. Science 318(5858):1917PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  1. 1.Department of Neurobiology and PediatricsUniversity of Utah School of Medicine Eccles Institute of Human GeneticsSalt Lake CityUSA

Personalised recommendations