[Neo-oogenesis in the postnatal ovary: fantasy or reality?]

The central dogma of female reproductive biology has long held that oogenesis ceases around birth in almost all mammals. Consequently, the ovarian reserve is definitely fixed and will continuously deplete up to the menopause in humans. New papers by Johnson et al. (2004) and by Bukovsky et al. (2004, 2005) overturn this dogma since they claim that female mice and women, respectively, produce new oocytes during adult life. The following review is mainly devoted to an analysis of the study by Johnson et al. (2004) as well as unpublished data submitted for publication from the same authors. Two bodies of evidence were presented to support their hypothesis: morphologic and experimental. Whereas morphologic data can be easily refuted, experimental data remain disturbing. In conclusion, these recent observations need to be confirmed by others, and extended by additional supporting evidence before they could be considered to question the dogma of a fixed stock of oocytes at birth.