Pre-embryo

Last updated

In human embryonic development, a pre-embryo is a conceptus before implantation in the uterus. [1]

Contents

Pre-embryo in human embryonic development

The word pre-embryo is sometimes used in ethical contexts to refer to a human conceptus at least between fertilization and implantation, though this term has not been adopted by the scientific community. [2] A conceptus between fertilization and implantation is also frequently classified as a pre-implantation embryo. [2]

Even after implantation begins, a pre-embryo may exist up until the formation of the primitive streak. [3] Implantation begins about six days after fertilization, and lasts for about a week, during which time formation of the primitive streak occurs. [4]

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. [1] [5] [6] One rationale that has been advanced for distinguishing an early fertilized human conceptus from an 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. [7]

In the United States, a report by the National Institutes of Health stated that a conceptus could be both a pre-implantation embryo and a pre-embryo at the same time. [8] However, Ann Kiessling (a leader in stem cell research) has written that those categories are inaccurate. [9]

Ontological status

The ontological status of the proembryo, embryo, and fetus Embryogenesis1.jpg
The ontological status of the proembryo, embryo, and fetus

The illustration shows the ontological status of the preembryo, embryo, and fetus:

The colors represent the maternal and paternal genetic contributions.

See also

Footnotes

  1. 1 2 Spallone, Patricia. “Bad Conscience and Collective Unconscious: Science, Discourse and Reproductive Technology” in Rosenbeck, Bente et al. Forplantning, køn og teknologi, pages 131-132 (Museum Tusculanum Press 1995).
  2. 1 2 Dyson, Anthony and Harris, John. Ethics and Biotechnology, page 94 (Routledge 1994).
  3. ↑ Pickering, Neil and Evans, Donald. Creating the Child, page 39 (Martinus Nijhoff Publishers 1996).
  4. ↑ Steinbock, Bonnie. “Life Before Birth,” pages 50 and 214-215 (Oxford University Press 1992).
  5. ↑ Mulkay, Michael. The Embryo Research Debate, page 31 (Cambridge University Press 1997).
  6. ↑ Braude, Peter. “Preimplantation Genetic Diagnosis and Embryo Research-Human Developmental Biology in Clinical Practice,” International Journal of Developmental Biology, volume 45, page 607 (2001).
  7. ↑ Ashley, Benedict and O’Rourke, Kevin. Ethics of Health Care: An Introductory Textbook, page 127 (Georgetown University Press 2002).
  8. ↑ Report of the Human Embryo Research Panel of the National Institutes of Health Archived 2009-01-30 at the Wayback Machine (1994).
  9. ↑ Kiessling, Ann. What is an Embryo?” Connecticut Law Review 36 (4): 1051–93.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.