Fig. 2.

Ultrastructure of human MII stage oocytes obtained from IVM of vitrified-warmed GV-stage oocytes. Mitochondria are generally rounded and provided with few peripheral or transverse cristae. Note the presence of complexes between mitochondria and vesicles of smooth endoplasmic reticulum (a, b). Dumbbell-shaped, possibly dividing mitochondria can be occasionally found in the ooplasm (asterisk in d). Extensive vacuolization is showed in c. Cortical granules are sparse in the ooplam (b) and form a discontinuous layer beneath the oolemma in vitrified-warmed oocytes (a, d). Microvilli are seen on the oolemma of vitrified-warmed oocytes (b, c). ZP zona pellucida, m mitochondria, mv microvilli, MV mitochondria-vesicle complexes, Ly lysosome, V vacuoles, CG cortical granules (modified from: [52] Shahedi et al., 2013)