1. Age-associated alteration of oocyte-specific gene expression in polar bodies: potential markers of oocyte competence 
Ze-Xu Jiao, M.D., Ph.D., Min Xu, M.D., Ph.D., Teresa K. Woodruff, Ph.D. 
Fertility and Sterility 
Volume 98, Issue 2, Pages (August 2012)
DOI: /j.fertnstert
Copyright © 2012 American Society for Reproductive Medicine Terms and Conditions

2. Figure 1
Morphology of the first polar body (PB) (A–C) and the separation of the first PB from its associated metaphase II oocyte (D, E). (A) Intact PB of normal size; (B) fragmented PB; (C) enlarged PB; (D) zona pellucida removed; (E) separation of first PB from its sibling oocyte. Bar = 50 μm.
Fertility and Sterility  , DOI: ( /j.fertnstert )
Copyright © 2012 American Society for Reproductive Medicine Terms and Conditions

3. Figure 2
Morphology of metaphase II and fertilzed oocytes from young (A–C) and aged (D–F) mice. (A, D) metaphase II oocyte; (B, E) two-cell embryo; (C, F) blastocyst. Bar = 50 μm.
Fertility and Sterility  , DOI: ( /j.fertnstert )
Copyright © 2012 American Society for Reproductive Medicine Terms and Conditions

4. Figure 3
(A) Oocyte-specific gene expression in metaphase II oocytes from young and aged mice. Results are normalized to each transcript in metaphase II oocyte from young mice as 1 (the calibrator). Compared with young oocytes, there was a significantly lower level of H1foo, Nlrp5, Tcl1, and Zp3 transcripts in aged oocytes. Error bars represent SD. *Significance relative to young mice (P<.05). (B) Oocyte-specific gene expression in polar body (PB) from young and aged mice. Results are normalized to each transcript in PB from young mice as 1 (the calibrator). The PBs from aged mice had significantly lower levels of all six transcripts compared with PBs from young mice. Error bars represent SD. *Significance relative to young mice (P<.05). (C) Relative abundance of each single gene in PB compared with its sibling oocyte. If the normalized messenger RNA (mRNA) level of each transcript in sibling oocytes is set at 1, the abundance of the transcript in PBs was consistently lower than that in the sibling oocytes. In addition, transcript levels were significantly lower in aged animals compared with young animals. Error bars represent SD. Horizontal dashed line indicates the normalized level in sibling oocyte. *Significance relative to its sibling oocyte (P<.05).
Fertility and Sterility  , DOI: ( /j.fertnstert )
Copyright © 2012 American Society for Reproductive Medicine Terms and Conditions