The continued presence of stem cells and oogonia in the adult mammalian ovary

Sir, We would like to comment on a recently published article (Byskov et al., 2011) that contradicts presence of germ stem cells or oogonia in the post-natal human ovary after the final clearing of these cells during the first 1 or 2 years of life. Presence of stem cells in adult ovary is a controversial area of research and needs to be resolved by the reproductive biologists. We have previously published data that choice of fixative and antigen retrieval protocols are crucial to detect Oct-4positive cells in testicular tissues (Bhartiya et al., 2010). Similarly, Oosterhuis et al. (2011) have also recently reported that Oct-4 is an extremely sensitive and specific marker for human malignant germ cell tumors but may give false-negative in biopsies fixed in Bouin's or Stieve's fixative. We consider that these may provide reasons that germ stem cells or oogonia might have been missed in the post-natal Bouin's fixed human ovary by Byskov et al. We request the group to refer to our recent publication (Parte et al., 2011) wherein we report that a gentle scraping of adult human, sheep, monkey and rabbit ovary surface releases stem cells in medium which can be characterized for various pluripotent markers by immunolocalization studies or by reverse transcription polymerase chain reaction. We continue to assert that stem cells do exist in adult ovaries and persist after menopause sets in.