Cryo-survival, fertilization and early embryonic development of vitrified oocytes derived from mice of different reproductive age

Abstract

Purpose To evaluate the effect of female reproductive age on oocyte cryo-survival, fertilization and the subsequent embryonic development following vitrification using the mouse model in order to address the question of how maternal reproductive age is related to fertility preservation. Methods Oocytes were collected from mice of different reproductive age: (1) 8-10 weeks, (2) 16-20 weeks, (3) 32-36 weeks, and (4) 44-48 weeks. Following vitrification and warming, the oocytes in each group were assessed for cryo-survival, fertilization and embryonic development as well as for the quality of blastocysts. Fresh oocytes without undergoing vitrification were used in each age group as controls. ResultsThe mean number of oocytes retrieved following superovulation was found to reduce significantly (P<0.05) in mice from 32-36 weeks of age (18.1±8.5) compared with 8-10 weeks of age (26.8±9.8) and 16-20 weeks of age (23.9±4.2) respectively. The cryo-survival rate of oocytes was reduced significantly (P<0.05) in mice of 44-48 weeks of age (90.4%±7.9) compared with the other 3 groups (98.8%±2.1, 98.0%±3.3 and 98.5%±2.2, respectively). The cleavage rate of vitrified oocytes declined significantly following the increase in maternal age in mice of 32-36 weeks of age (69.7%±20.8) forward (63.6%±9.2). However, no significant difference in the cleavage rate was found among the control groups of different maternal ages. The rate of embryo development to the blastocyst stage in the vitrified oocytes also significantly declined following the increase in maternal age (71.8%± 8.8, 66.4%±10.7, 64.2%±17.4 and 4.1%±8.3 respectively).There were no such differences in the rates of embryo development to the blastocyst stage among the control groups following the increase in maternal age (75.9%±12.2, 79.5%±28.9, 70.2%±17.4 and 69.3%±19.0 respectively). However, the quality of blastocysts produced from 32-36 weeks and 44-48 weeks of ages was significantly poor in term of total cell numbers and the ratio of inner cell mass(ICM) / trophectoderm (TE) compared to younger age in both vitrified and control groups Conclusions Cryo-survival of oocytes following vitrification and warming procedures is associated with female reproductive age. There is a more negative impact on the oocytes following vitrification and warming with the increase of maternal age.Keywords Female reproductive age . Oocytes . Cryo-survival . Fertilization . Embryonic development . Blastocyst Capsule Reduction in fertilization rate and poor embryonic development following vitrification procedure has been found to be associated with increased reproductive age.

Age-associated changes in bovine oocytes and granulosa cell complexes collected from early antral follicles

“…In addition, low total cell number of the blastocysts was also observed in mice [53]. When OGCs of EAFs were cultured in medium containing 0.1 μg/mL E 2 , the ratio of polyspermic fertilization of oocytes grown in vitro was higher for aged groups than that for young groups.…”

The presence of 1 mM glycine in vitrification solutions protects oocyte mitochondrial homeostasis and improves blastocyst development

“…In addition many of the studies that demonstrate comparable pregnancy rates between fresh and vitrified oocytes are undertaken using young oocyte donors and it is likely that oocyte quality can play a role susceptibility to damage during cryopreservation [14]. Studies using animal models have demonstrated that the negative impact of vitrification on the oocyte increases with maternal age so it is likely that the impact of vitrification in older women will be far greater than that of young donors however this has not been investigated [71].…”

Current progress in oocyte and embryo cryopreservation by slow freezing and vitrification

“…However, in cows, non-surgical frozen ET resulted in lower pregnancy rate compared with surgical transfer (38.5 vs 71.1%). In a study on mouse oocytes, age-related decrease in the number of oocytes retrieved following superovulation was noted (Yan et al 2010). Oocytes retrieved from older females had lower survival and cleavage rate after vitrification, rate of development to blastocyst went down with maternal age when oocytes were vitrified but not in the control (no vitrification), and blastocyst quality (total cell number and ratio of inner cell mass to trophectoderm) was lower in the older age groups in both vitrified and control treatments.…”