Table 1.

Key observations advanced in support of neo-oogenesis in mammals, and proposed alternative explanations.

Section	Observation	Interpretation by proponents of neo-oogenesis	Alternative explanation consistent with a fixed oocyte reserve.
2.(i)	BrdU-incorporation in Mvh+ germ cells located in the OSE [7,10].	Mitosis in germline stem cells.	MtDNA synthesis, and DNA recombination and repair in tardy oocytes, in the neonatal ovary.
	Mvh+ germ cells located in the OSE [7-9].	Existence of a germinal epithelium.	Oocytes in transit across the OSE during exfoliation [54].
2.(ii)	"Oocyte-like" phenotype of cells in OSE-derived cultures [8,9].	De novo formation of immature and secondary ocytes from stem cells.	Nondescript cells undergoing oncosis.
	Small, round cells, above and below the OSE [9].	Putative female germline stem cells.	Small immune cells in the OSE [54].
	"Embryoid body-like" and "blastocyst-like" structures [9] in OSE-derived cultures.	Pathenogenetic activation of de novo oocytes.	Nondescript cellular aggregates, and vesicles of OSE.
	Expression of Oct4, Sox2, Nanog and c-kit by OSE derivatives [9].	Embryonic-like, germline stem cells.	Cultures containing regenerative epithelium [58].
	Cell lines producing early oocytes [11].	Female germline stem cell lines.	Mixed cultures of OSE, early oocytes and/or oogonia.
2.(iii)	BU-induced depletion of the follicle pool [7,15] and extinction of fertility.	Destruction of replicative, female germline stem cells by BU treatment, without atresia.	Induction of oocyte atresia by BU treatment; and proof of absence of female germline stem cells.
2.(iv)	EGFP+ cells with germ-cell markers in ovaries of CT-treated mice following BMT or PBCT [12,13].	De novo oocytes from bone marrow-derived precursors.	Oct4-expressing macrophages; and autofluorescent, somatic cells of the ovary.
	Presence of PGC and HSC in extraembryonic regions during early post-implantation development [12].	Incorporation of oocyte precursors within the haematopoietic system.	Distinct temporal and spatial niches for the origins and migration of germinal and haematopoietic lineages.
2.(v)	Replicative, unipotent oocyte-like cells [10].	Existence of female germline stem cells.	Residual oogonia induced to proliferate by specified culture conditions, and expansion of populations of functional oogonia.
	Immuno-magnetic isolation of Mvh+ proliferating cells from disaggregated ovaries [10].	Selective purification of stem cells via Mvh binding to anti-Mvh antibody.	Harvesting of oogonia and primary oocytes due to Mvh binding to anti-Mvh antibody, or to Fc receptors on the plasma membrane of oogonia and oocytes binding to Fc moiety of antibody.
3.	Restoration of the host follicle pool in CT-treated mice following BMT [12,13].	Stimulation of endogeneous, de novo oogenesis.	Induction of autoimmunity to ovarian antigens by CT; and rescue of fertility via tolerance restored by haematopoietic chimaerism.