Fig. 1.

Live human mature oocytes observed at the inverted microscope. a The bull-eye inclusion (arrow) appears as a prominent smooth, moderate dense, round structure surrounded by a cavitated region. Note the zona pellucida (ZP), the perivitelline space (PVS), and the first polar body (1PB). b Refractile body (arrow). Note the prominent structure made by rough dense materials without evident membrane limits. c Small granular vacuole (arrow). Note the evident membrane limits and the presence of a large aggregate of rough dense inclusions. d Medium-sized granular vacuole (arrow). Note the evident membrane limits and the presence of small aggregates of rough dense inclusions around the periphery. e Large aggregate of smooth tubular endoplasmic reticulum (arrow). This inclusion is generally larger, presents a homogeneous pale content without inclusions, and displays no evident limiting membrane. f Vacuole (arrow). This inclusion is generally larger, presents a homogeneous pale content without inclusions, and displays an evident limiting membrane. a–f 20 μm. g Ultrastructure of a morphological normal human mature metaphase II oocyte immediately processed after denudation. Note the ZP coat, the narrow PVS, and the short microvilli (mv). In the cortex, dense cortical vesicles (cv) and tiny smooth endoplasmic reticulum (SER) vesicles (arrows) can be observed. In the subcortex, small SER vesicles surrounded by one to two mitochondria (v), large SER vesicles surrounded by several mitochondria (LV), a tubular SER aggregate (aSERT), isolated SER tubules (t), and isolated mitochondria (mi) can be observed. g 1 μm