Mitochondrial DNA content affects the fertilizability of human oocytes

• Published in: Molecular human reproduction Vol. 7; no. 5; pp. 425 - 429
• Main Authors: Reynier, P., May-Panloup, P., Chrétien, M-F., Morgan, C.J., Jean, M., Savagner, F., Barrière, P., Malthièry, Y.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.05.2001; Oxford Publishing Limited (England)
• Subjects: Adult; Biological and medical sciences; Cell Extracts; cytoplasmic maturation; DNA, Mitochondrial - physiology; Female; Fertilization - genetics; Fertilization - physiology; Fundamental and applied biological sciences. Psychology; Humans; Male; Mammalian female genital system; mitochondrial biogenesis; Morphology. Physiology; mtDNA; oocyte; Oocytes - physiology; real-time PCR; Vertebrates: reproduction; Human; Polymerase chain reaction; Fertility; Female; Mitochondrial DNA; Real time processing; Germinal cell; Cytoplasm; Oocyte; Oocyte maturation
• ISSN: 1360-9947; 1460-2407
• DOI: 10.1093/molehr/7.5.425

Mitochondrial DNA content varies considerably in oocytes, even when collected from the same patient. In the present study, real-time quantitative polymerase chain reaction analysis of 113 unfertilized oocytes obtained from 43 patients revealed an average of 193 000 (range: 20 000 to 598 000) mitochondrial genomes per cell. We compared several groups of oocytes to investigate the relationship between mitochondrial DNA content and fertilizability. The average mitochondrial DNA copy number was significantly lower in cohorts suffering from fertilization failure compared to cohorts with a normal rate of fertilization. In addition, the mitochondrial copy number of oocytes from patients with fertilization failure due to unknown causes was significantly lower than that of oocytes from patients in which IVF failure was due mainly to a severe sperm defect. The lower mtDNA copy number could be due to defective cytoplasmic maturation of oocytes. We conclude that low mitochondrial DNA content, due to inadequate mitochondrial biogenesis or cytoplasmic maturation, may adversely affect oocyte fertilizability.