Abstract (EN):
The ultrastructure of cortical specializations formation in Penaeus kerathurus is presented. After vitellogenesis, the oocyte accumulates large amounts of small vesicles containing feathery structures (cortical vesicles). These vesicles exhibit direct connections with the rough endoplasmic reticulum, and their contents seem to arise from decondensation of the small dense granules contained inside the endoplasmic reticulum. Small cortical vesicles also appear to engulf cytosolic and yolk materials, and show intimate associations with glycogen granules. After formation, some of the small cortical vesicles fuse together to form medium size cortical vesicles which migrate towards the oocyte surface and finally fuse with the oolemma. These vesicles then grow inwards by continued fusion with Golgian vesicles and small cortical vesicles at their basolateral surface until forming the characteristic large cortical specializations. Despite fusion with the oolemma, cortical vesicle contents remain intact, except at the most apical region where the feathery elements disperse and merge with the overlying vitelline layer. These results show that in P. kerathurus cortical specializations are not the product of deep invaginations of the oocyte cytoplasmic membrane to where endogenous components are exocytated and concentrated, but that cortical rods and cortical crypts correspond to large cortical vesicles precociously fused with the oolemma.
Language:
English
Type (Professor's evaluation):
Scientific
No. of pages:
7