Proembryo

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The ontological status of the proembryo, embryo, and fetus

Proembryo, or preembryo, is a term created with the development of in vitro fertilization (IVF) to describe egg cells (ova) that have been fertilized but not yet implanted into a uterus. Dr. Ford (1988) suggested the term proembryo for this stage of development.^{[citation needed]}

A proembryo is the preimplantation, post fertilization stage in the human life cycle, where we have at least one new human being, but not yet an individual human being and thus not yet a person.^{[verification needed]} From the formation of the primitive streak (shortly following the completion of implantation), individuality has been determined, however there is debate as to whether this individual human being is, or should be considered, a person.

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

(o) indicates the (natural &) standard reproductive and embryogenic pathway
(mz) indicates all the possible pathways for a monozygotic twin (see Scott, 2002, Hall, 2003, for a review on monozygotic twinning)
(/c) indicates a clone created by either SCNT or ANT (See Hurlbut, 2005, and section III. Pluripotent Stem Cells Derived from Biological Artifacts in the PCBE's Report on alternative sources of stem cells for a review of ANT))
(ch) indicates all the possible pathways for a chimeric individual (see Charles E. Boklage, 2006, for a review on chimerism and twinning)
(dz) indicates the pathway of a dizygotic twin
(en) indicates an enucleated oocyte
(m) indicates a hydatidiform mole
(cm) indicates a complete hydatidiform mole
(pm) indicates a partial hydatidiform mole, and
(p) indicates parthenogenesis.