Ultrastructure of human mature oocytes after vitrification

Abstract

Since the introduction of human assisted reproduction, oocyte cryopreservation has been regarded as an attractive option to capitalize the reproductive potential of surplus oocytes and preserve female fertility. However, for two decades the endeavor to store oocytes has been limited by the not yet optimized methodologies, with the consequence of poor clinical outcome or of uncertain reproducibility. Vitrification has been developed as the promising technology of cryopreservation even if slow freezing remains a suitable choice. Nevertheless, the insufficiency of clinical and correlated multidisciplinary data is still stirring controversy on the impact of this technique on oocyte integrity. Morphological studies may actually provide a great insight in this debate. Phase contrast microscopy and other light microscopy techniques, including cytochemistry, provided substantial morpho-functional data on cryopreserved oocyte, but are unable to unraveling fine structural changes. The ultrastructural damage is one of the most adverse events associated with cryopreservation, as an effect of cryo-protectant toxicity, ice crystal formation and osmotic stress. Surprisingly, transmission electron microsco py has attracted only limited attention in the field of cryopreservation. In this review, the subcellular structure of human mature oocytes following vitrification is discussed at the light of most relevant ultrastructural studies.

Morphokinetics analysis of embryos derived from vitrified/warmed oocytes

“…Overall, present data assessing morphology and development of VODE and FODE do not show any major difference between the two groups. Our results are reassuring, and they are in line with published data showing that vitrification/warming cycles do not alter oocyte quality or resulting embryo development [6,11].…”

“…To date vitrification is the most attractive and reliable option to store oocytes, bringing about a dramatic change in the field of ART [9,10]. Although this technique was shown to have no major adverse effect on oocyte ultrastructure and oocyte in vitro performance [6,11], it was suggested to indirectly impact on derived embryo development [12]. To date, vitrified/ warmed oocyte-derived embryo kinetics and morphology have not yet been entirely documented.…”

Histological Characterization of Sacco's Concentrated Growth Factors Membrane

“…The sectioning started maintaining the major axis vertical. The sections were stained with haematoxylin-eosin (HE) and the Azan Mallory (AM) as previously described (Khalili et al 2012;Dunham & Schoenlein, 1927). The slides were observed using light microscope (Zeiss, AxioImager A2, Germany) and the images were captured by Leica DFC 320 camera.…”

Evaluation of the impact of vitrification on the actin cytoskeleton of in vitro matured ovine oocytes by means of Raman microspectroscopy

“…Different methods have been used to study the proteins of the cytoskeleton in the oocyte, [22], but they often require cell fixation and specific labels [18,23]. Recently, advances in imaging technology, as the polarized light microscopy technology, have offered the opportunity to visualize the meiotic spindle non-invasively before and/or after cryopreservation [24,25].…”