The present study aims to shed light on the origin of abnormal oocytes ovulated by aged females. In order to reach this goal, cellular and morphological traits of ovulated oocytes from hybrid (C57Bl/6JIco female × CBA/JIco male) female mice retrieved after exogenous ovarian stimulation at the age of 12, 40–42, 50–52, or 57–62 wk were analyzed. Aging of female mice was associated with 1) decreased number of ovulated oocytes; 2) increased percentage of cumulus-free oocytes; 3) raised percentage of oocytes with intracellular mitochondrial aggregates; 4) reduced percentage of oocytes displaying a normal distribution of chromosomes in the metaphase-II plate; 5) increased percentage of normal oocytes exhibiting a DNA-containing polar body (PB); 6) higher percentage of oocytes with chromosome scattering; 7) increased percentage of chromosome-scattered oocytes without a DNA-containing PB and with intracytoplasmic mitochondrial aggregates; 8) raised percentage of oocytes exhibiting chromosome decondensation; 9) lower percentage of chromosome-decondensed oocytes lacking both a DNA-containing PB and intracytoplasmic mitochondrial aggregates; 10) increased percentage of abnormal/degenerated oocytes; 11) reduced percentage of abnormal/degenerated oocytes displaying cellular fragmentation; and 12) higher percentage of abnormal/degenerated oocytes with mitochondrial aggregates exhibiting no nuclear/chromosomal DNA fluorescence, cellular fragmentation, milky or dark cytoplasm, or cellular remains enclosed by the zona pellucida. Although several studies suggest aging females may ovulate aged or overripened oocytes, these data support the hypothesis that old females ovulate an increased percentage of atretic/apoptotic oocytes coming from rescued follicles that would have become atretic earlier in life.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.