Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
3971141 | Reproductive BioMedicine Online | 2009 | 11 Pages |
This study describes and compares the possible effects of vitrification on the ultrastructural morphology of 20 human mature oocytes vitrified using two different supports, cryoleaf (n = 10) and cryoloop (n = 10). Fresh human mature oocytes (n = 15) were used as controls. Fresh and vitrified–warmed oocytes appeared rounded, with a homogeneous cytoplasm, an intact oolemma and a continuous zona pellucida. Sparse microvacuolization was only occasionally detected in fresh and vitrified–warmed oocytes, to the same extent. About 50% of the vitrified oocytes contained atypical, small and slender mitochondria–smooth endoplasmic reticulum aggregates, whereas a non-homogeneous microvillar pattern was observable in only 30% of the oocytes subjected to vitrification, regardless of the support utilized. Cortical granule content appeared generally reduced after vitrification, but cryoleaf-supported oocytes contained more cortical granules than cryoloop-supported oocytes (P < 0.05). Thus good overall preservation and virtual absence of cytoplasmic vacuolization seem to be the most relevant markers of quality in vitrified–warmed oocytes, using either support. In addition, cryoleaf-supported oocytes retained a higher number of cortical granules than cryoloop-supported oocytes. The variety of ultrastructural alterations recorded emphasizes the need for further studies aimed at assessing the actual tolerance of human oocytes to vitrification.