Table 1. Comparison of mitochondrial DNA copy number of embryos 48 h after insemination among age groups.
Developmental stage | mtDNA number (Mean ± SE) | ||||||||||||||
All ages (n=49) | Young (n=18) | Middle (n=12) | Aged (n=19) | Aged (>180)* (n=7) | |||||||||||
>7-cell | 587,536 | ± | 104,277a | 501,818 | ± | 163,051 | 674,356 | ± | 216,656 | 647,661 | ± | 203,372 | 118,408 | ± | 106,535 |
4-to 7-cell | 463,796 | ± | 49,815ab | 563,569 | ± | 52,664 | 357,376 | ± | 64,052 | 446,055 | ± | 81,851 | 301,181 | ± | 52,016 |
2-to 3-cell | 397,852 | ± | 43,731ab | 335,085 | ± | 74,154 | 336,218 | ± | 87,734 | 494,735 | ± | 69,936 | 240,436 | ± | 65,043 |
Non cleaved | 353,039 | ± | 43,345b | 444,072 | ± | 78,958 | 286,554 | ± | 69,663 | 332,980 | ± | 63,891 | 141,590 | ± | 64,694 |
All | 418,020 | ± | 42,183ab | 495,612 | ± | 91,018 | 342,556 | ± | 40,022 | 392,173 | ± | 60,445 | 216,472 | ± | 30,764 |
Embryos 48 h after insemination were divided into >7-cell stage, 4-to 7-cell stage and 2-to 3-cell stage embryos and noncleaved oocytes. mtDNA number per stage was measured. Cows were divided into age groups: Young 25–45 months, Middle, 45–120 months, Aged, >120 months, and Aged* >180 months. a–b: P<0.05.