Mitochondrial DNA Essential for Successful Oocyte Fertilization
Fertility and Sterility 2006; 85: 584-91
The content of mitochondrial DNA (mtDNA) in oocytes is crucial to the outcome of fertilization attempts, and may explain some cases of fertilization failure, study findings indicate.
There are many factors that may affect the fertilizability of an oocyte, in addition to which there is a considerable degree of unexplained infertility. Although mitochondria are dormant during fertilization itself, they play a vital role during embryonic development.
Justin St. John, from the University of Birmingham Medical School in the UK, and colleagues enrolled 54 women seeking infertility treatment, studying a total of 35 fertilized oocytes from 21 patients, 65 unfertilized oocytes from 36 patients, and 42 degenerate oocytes from 23 patients. Polymerase chain reaction assay was used to determine mtDNA content.
For fertilized oocytes, the average mtDNA copy number was 250,454, while it was just 163,698 in the unfertilized oocyte group. For the degenerate oocyte group, the average mtDNA copy number was only 44,629. Interestingly, there were significant differences in mtDNA copy number between male factor and female factor infertility patients and between unexplained and female factor infertility patients.
"It is evident from our data that a very strong association exists between the number of mitochondria, based on the number of mtDNA genomes present, and fertilization outcome," the team writes.
