Abstract
The possible presence of oocyte and granulosa cells originated from stem cells in the adult mammalian ovaries was claimed by some studies which will lead to major changes in reproductive biology and infertility treatments. Purpose of this research is to investigate the possible existence and the location of the potential stem cells in mouse ovaries. In this study, the ovaries from 2-week (pre-puberty) and 8-week (adult) old BALB-C mice were used. For the investigation of the presence of possible stem cells, the expression profiles of three well known stem cell markers, Oct-4, Nanog and Sox2 were determined in the ovaries of two different age groups by real time quantitative RT-PCR (qRT-PCR). Protein expression levels and their localization in the ovary cells were immunohistochemically evaluated on fresh-frozen ovary tissue sections by using monoclonal antibodies specific to Sox2, Nanog and Oct-4. The gene expression levels of Oct-4 and Nanog were found to be significantly differentiated between 2-week old and 8-week old mice whereas no significant difference was observed in the expression level of Sox2 between two age groups. Immunohistochemistry results showed the presence of both Sox2 and Oct-4 protein in the cytoplasm of ovarian epithelial cells, granulosa cells, oocytes and theca cells. Nanog protein was observed only in the nucleus of the oocytes and furthermore the expression of Nanog was higher in eight weeks old samples compared to two weeks old ones according to qRT-PCR results. These results suggest for the first time that Nanog protein is expressed both in adult and pre-puberty mouse ovaries and locate at the nucleus of the oocytes and to the best of our knowledge this is the first study that shows the differential expression of Oct-4, Nanog and Sox2 in pre-puberty and adult mouse ovaries by qRT-PCR. Collectively, our results may suggest that both pre-puberty and adult mice ovaries accommodate cells carrying stem cell features.
Highlights
According to the results of extensive research on the reproductive biology of most mammalian females, all germ cells at the end of fetal development enters meiosis, since after birth ovary contain limited number of oocytes
These results suggest for the first time that Nanog protein is expressed both in adult and pre-puberty mouse ovaries and locate at the nucleus of the oocytes and to the best of our knowledge this is the first study that shows the differential expression of Oct-4, Nanog and Sox2 in pre-puberty and adult mouse ovaries by quantitative RT-PCR (qRT-PCR)
The results of the qRT-PCR analysis showed that the expression of the Oct-4 and Nanog genes were signifycantly differentiated between two and eight weeks-old (Oct-4; p = 0.05, Nanog; p = 0.01) ovary samples
Summary
According to the results of extensive research on the reproductive biology of most mammalian females, all germ cells at the end of fetal development enters meiosis, since after birth ovary contain limited number of oocytes. If this resource is lost due to sickness or injury of ovary, there is no possibility of renewal. By manipulation of prepubertal female mice with the mitotic germ-cell toxicant busulphan eradicates the primordial follicle source by early adulthood without stimulating atresia They manifest cells expressing the meiotic entry marker synaptonemal complex protein 3 (SCP3) in juvenile and adult mouse ovaries. Wild-type ovaries grafted into transgenic female mice with omnipresent expression of green fluorescent protein (GFP) become penetrated with GFP-positive germ cells that form follicles [1]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
