Ultrastructure and intracellular calcium response during activation in vitrified and slow-frozen human oocytes

Abstract

Closed vitrification based on DMSO and EG preserves the ultrastructural features and the ability to respond to the Ca²⁺ ionophore A23187 significantly better than does slow freezing with 0.3 M sucrose. Damage to organelles involved in the [Ca²⁺](i) modulation might reduce the developmental competence of cryopreserved oocytes.

An insufficient increase of cytosolic free calcium level results postovulatory aging-induced abortive spontaneous egg activation in rat

“…An increase of cytosolic free Ca 2+ (due to burst from internal stores) induces EA during fertilization [5,38,39]. Further, CI increases cytosolic free Ca 2+ level [35] and induces EA in several mammalian species [11,14,16,32,[40][41][42]. In the present study, we used CI as a positive control and data suggest that CI induced morphological features characteristics of EA in a dose-dependent manner.…”

Comparison of cytoskeletal integrity, fertilization and developmental competence of oocytes vitrified before or after in vitro maturation in a porcine model

“…Accordingly, an increased frequency of non-penetrated parthenogenetic oocytes was observed in the matured-vitrified group in the present study. A plausible explanation for this phenomenon may be alteration or damage of Ca 2+ regulating organelles such as mitochondria and the endoplasmic reticulum, as reported previously in mouse, porcine and human oocytes [8][9][10]15].…”

Autophagic activation in vitrified–warmed mouse oocytes

“…In human oocytes, vitrifiedwarmed oocytes tend to recover cellular volume and spindle structure faster than slow-frozen oocytes (Martinez-Burgos et al 2011). In addition, the ultrastructural features and the intracellular calcium response are better maintained in vitrified-warmed oocytes than in slow frozen oocytes (Gualtieri et al 2011).…”

“…CPA-treated oocytes are placed in cryo-containers and are exposed to liquid nitrogen (LN 2 ) (Gosden 2011, Saragusty & Arav 2011. Several indicators have been used to assess the quality of vitrified-warmed oocytes, including the embryonic developmental rate after IVF, the state of the meiotic spindle, DNA damage, the production of reactive oxygen species, and ultrastructural changes (Bromfield et al 2009, Gualtieri et al 2011, Martinez-Burgos et al 2011, Tatone et al 2011. However, the status of autophagy in vitrified-warmed oocytes has not been studied.…”