The perivitelline space-forming capacity of mouse oocytes is associated with meiotic competence.
Although mouse oocytes progressively acquire meiotic competence during their growth in the ovaries, only half of full-grown oocytes can accomplish meiosis. Two types of full-grown oocytes have been reported on the basis of their chromatin configuration, the surrounded-nucleolus (SN) type and the non-surrounded-nucleolus (NSN) type. Therefore, full-grown oocytes collected from the ovaries of adult animals comprise a heterogeneous population; some oocytes are meiotically incompetent (NSN-type), and some are competent (SN-type). In the present study, we found that full-grown oocytes could be classified into two groups using the criterion of formation of the perivitelline space (PVS) after culture with 3-isobutyl-1-methylxanthine (IBMX) for 1 h. In oocytes with a PVS, actin-filled processes within zona pellucidae originating from cumulus cells were reduced, while they were rich in oocytes without a PVS, suggesting that a reduction in these processes contributes to PVS formation. PVS formation was highly correlated with meiotic competence and SN-type configuration. The results of this study demonstrate that PVS formation is a useful criterion for easily distinguishing between SN- and NSN-type oocytes, without injury to the cells.
Inoue
Azusa
A
Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Chiba, Japan.
Akiyama
Tomohiko
T
Nagata
Masao
M
Aoki
Fugaku
F
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000199:Actins / Q000378:metabolism; D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure*; D002478:Cells, Cultured; D002843:Chromatin / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D008540:Meiosis; D051379:Mice; D009865:Oocytes / Q000145:classification* / Q000254:growth & development / Q000648:ultrastructure*; D009866:Oogenesis; D015044:Zona Pellucida / Q000502:physiology
D000199:Actins; D002843:Chromatin; D015056:1-Methyl-3-isobutylxanthine