Mitochondrial dysfunction of in vitro grown rabbit oocytes results in preimplantation embryo arrest after activation.
To clarify the mechanism that impairs development of in vitro grown (IVG) oocytes, we assessed whether the developmental disability of IVG oocytes is caused by cytoplasmic dysfunction. First, we assessed the cleavage of nuclear-substituted oocytes cultured in vitro. The nuclei, but not the cytoplasm, of the IVG oocytes were able to support subsequent cleavage after artificial activation. The mitochondrial activity of the oocytes increased as the follicles grew. However, the mitochondrial activity of the IVG oocytes was significantly lower than that of ovulated oocytes and oocytes recovered from follicles with diameters of more than 300 microm. Furthermore, the expression levels of mitochondrial transcriptional factor A (TFAM) in the oocytes increased in a similar manner. However, the expression levels of TFAM in the IVG oocytes was significantly lower than that of ovulated oocytes and oocytes recovered from follicles with diameters of more than 300 microm. Taken together, these results indicate that the low developmental competence of IVG oocytes is caused by a cytoplasm deficiency due to low mitochondrial activity.
Kanaya
Hiroyuki
H
Department of Biology-Oriented Science and Technology, Division of Genetic Engineering, Kinki University, Japan.
Hashimoto
Shu
S
Teramura
Takeshi
T
Morimoto
Yoshiharu
Y
Matsumoto
Kazuya
K
Saeki
Kazuhiro
K
Iritani
Akira
A
Hosoi
Yoshihiko
Y
D000818:Animals; D001755:Blastocyst / Q000502:physiology*; D046149:Embryo Culture Techniques; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D005307:Fertilization in Vitro / Q000009:adverse effects*; D008928:Mitochondria / Q000502:physiology*; D053652:Nuclear Transfer Techniques; D009865:Oocytes / Q000502:physiology*; D011817:Rabbits; D008941:Spindle Apparatus / Q000502:physiology