In vitro-matured rat oocytes have low mitochondrial deoxyribonucleic acid and adenosine triphosphate contents and have abnormal mitochondrial redistribution.
OBJECTIVE
To study the development and function of mitochondria in in vitro-matured rat oocytes derived from follicles of different sizes.


METHODS
Experimental animal study.


METHODS
Department of Anatomy at the University of Hong Kong.


METHODS
Immature female Sprague-Dawley rats that were 25 days of age.


METHODS
Immature oocytes were collected from rat ovarian follicles of different sizes and were induced to mature in vitro.


METHODS
The number of copies of mitochondrial DNA, mitochondrial activity, adenosine triphosphate content of matured oocytes, and rates of fertilization and blastulation were determined.


RESULTS
The mitochondrial DNA copy number of oocytes increased linearly with the diameter of antral follicles. The mitochondrial DNA copy number, adenosine triphosphate content, and proportion of oocytes with peripheral distribution of mitochondria in in vitro-matured oocytes from small antral follicles were significantly lower than those from preovulatory follicles and in vivo-matured oocytes. Compared with in vitro-matured oocytes from small antral follicles, those from preovulatory follicles and in vivo-matured oocytes also had significantly better fertilization potential and higher blastulation rate.


CONCLUSIONS
The inferior developmental potential of in vitro-matured oocytes may be attributed partly to a reduced number of mitochondria, resulting in insufficient production of adenosine triphosphate for required developmental events.
Zeng
Hai-Tao
HT
Department of Obstetrics and Gynecology, University of Hong Kong, Hong Kong, Special Administrative Region.
Yeung
William S B
WS
Cheung
May P L
MP
Ho
Pak-Chung
PC
Lee
Calvin K F
CK
Zhuang
Guang-Lun
GL
Liang
Xiao-Yan
XY
O
Wai-Sum
WS
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D036703:Blastula / Q000378:metabolism; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002478:Cells, Cultured; D004272:DNA, Mitochondrial / Q000378:metabolism*; D046149:Embryo Culture Techniques; D047108:Embryonic Development; D004734:Energy Metabolism; D005260:Female; D005307:Fertilization in Vitro; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014475:Uncoupling Agents / Q000494:pharmacology
D004272:DNA, Mitochondrial; D014475:Uncoupling Agents; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D000255:Adenosine Triphosphate