Cryopreservation of metaphase II human oocytes effects mitochondrial membrane potential: implications for developmental competence

Abstract

Irreversible loss of high DeltaPsim in thawed oocytes may be associated with defects in Ca2+ signalling after insemination and could have downstream consequences for normal embryogenesis.

Mitochondria in human oogenesis and preimplantation embryogenesis: engines of metabolism, ionic regulation and developmental competence

“…In MII mouse and human oocytes and embryos (Ahn et al 2002, 2003, Jones et al 2004, the highest intensity of J-aggregate fluorescence is reported to occur in the pericortical/subplasmalemmal cytoplasm (arrows, Fig. 1K).…”

“…For example, owing to the absence of an intrafollicular vasculature, the oocyte may reside in a near anoxic The potential developmental relevance of pericortical J-aggregate fluorescence to high polarized mitochondria in the oocyte and early embryo, and differential J-aggregate fluorescence between the mural (mTR) and polar trophectoderm (pTR) and inner cell mass (ICM) are discussed in the text. Amy Jones provided image K (see also Jones et al 2004). Green fluorescence in this image is derived from JC-1 monomeric staining in low polarized mitochondria.…”

“…The unique capacity of JC-1 to report differences in DC M has been used in a variety of studies of somatic cells under normal and experimental conditions, and more recently, for mammalian oocytes and embryos to examine the association between developmental competence and mitochondrial activity (Wilding et al 2001, 2003, 2003, Acton et al 2004, Jones et al 2004. In MII mouse and human oocytes and embryos (Ahn et al 2002, 2003, Jones et al 2004, the highest intensity of J-aggregate fluorescence is reported to occur in the pericortical/subplasmalemmal cytoplasm (arrows, Fig.…”

“…Ahn et al (2002) reported that thawed 2-cell mouse embryos that failed to divide or that developed abnormally showed a cryopreservation-associated loss of mitochondrial hyperpolarization in the subplasmalemmal domain. Jones et al (2004) found that cryopreservation of MII human oocytes was accompanied by loss of the hyperpolarized pericortical mitochondrial domain that characterized the fresh oocyte. Thawed oocytes also exhibited a significantly reduced capacity to up-regulate levels of intracellular free Ca 2þ in response to Ca 2þ ionophore stimulation.…”

Oocyte morphology does not affect post-warming survival rate in an egg-cryobanking donation program

“…Oocyte cryopreservation has been associated with intracellular organelles and cytoskeleton injuries, such as alteration in mitochondrial function [4], hardening [5] and fracturing [6] of the zona pellucida, microtubules damage [7,8], ultrastructural alterations in microdomains and meiotic spindle damage [9][10][11][12], which are presumably linked to the reduced developmental potential of cryopreserved oocytes [13]. However, protection of the meiotic spindle has been inferred by the addition of cryoprotectants [14] and by de novo spindle reconstruction following warming [15].…”