Changes in the distribution of mitochondria before and after in vitro maturation of human oocytes and the effect of in vitro maturation on mitochondria distribution.
OBJECTIVE
To clarify the relationship between oocyte maturation and mitochondria distribution and assess the effects of in vitro maturation (IVM) on the distribution of mitochondria in human oocytes.


METHODS
Prospective randomized trial.


METHODS
Hospital-based IVF center.


METHODS
One hundred fifty-eight patients undergoing intracytoplasmic sperm injection (ICSI) treatment for male factors or combined with oviduct infertility and fifteen patients undergoing controlled ovarian hyperstimulation followed by coitus or IUI.


METHODS
Of all the 284 immature oocytes, 140 were fixed directly. The others were prepared for IVM before they were fixed. All the 21 oocytes matured in vivo were fixed directly and stained for mitochondria. Both immature and mature oocytes were stained by Mito Tracker Green FM. The distribution of mitochondria was observed using a confocal laser scanning microscope.


METHODS
Mitochondrial distribution.


RESULTS
Three mitochondria distribution patterns were identified: peripheral, semiperipheral, and evenly diffused. A peripheral distribution of mitochondria was presented by 64.1% (50/78) of the germinal vesicle (GV) oocytes; 45.2% (28/62) of the meiosis I oocytes maintained the peripheral distribution; and 38.7% (24/62) presented a diffused status. After IVM, 75.5% (80/106) of the oocytes displayed an evenly diffused type of distribution. The mitochondria were more abundant in the inner cytoplasm than in the peripheral region in most of the oocytes matured in vivo.


CONCLUSIONS
There are obvious changes in the distribution of mitochondria in human oocytes before and after maturation. Distribution of mitochondria in oocytes matured in vitro is slightly different from that of oocytes matured in vivo. The results may partially explain the reduced developmental potential of oocytes matured in vitro compared with those matured in vivo.
Center for Reproductive Medicine, Shandong Provincial Hospital, Shandong University, Key Laboratory of Reproductive Medicine, Shandong Province, Jinan 250021, People's Republic of China.
Shan
S
Liu
Yuan
Y
Li
Xuan
X
Gao
Jun-Hao
JH
Yan
Zi-Jiang
ZJ
Chen
D000328:Adult; D000447:Aldehydes; D002478:Cells, Cultured; D005260:Female; D005456:Fluorescent Dyes; D006801:Humans; D007246:Infertility / Q000473:pathology / Q000628:therapy*; D007315:Insemination, Artificial; D008540:Meiosis; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000473:pathology*; D009865:Oocytes / Q000473:pathology*; D010062:Ovulation Induction; D011446:Prospective Studies; D027724:Reproductive Techniques, Assisted; D020554:Sperm Injections, Intracytoplasmic; D013997:Time Factors; D055815:Young Adult
D000447:Aldehydes; D005456:Fluorescent Dyes; C111472:mitotracker green FM