Ultrastructure of jumbo tiger prawn (Penaeus monodon) oocytes: late maturation stage
1988
Prapee Sretarugsa | Prasert Sobhon | Porncharn Saitongdee (Mahidol Univ., Bangkok (Thailand). Faculty of Science. Dept. of Anatomy)
Late maturation stage of jumbo tiger prawn (P. monodon) oocytes were collected from four different parts of ovary: the anterior thoracic, upper abdominal, middle abdominal and lower abdominal regions, respectively. All oocytes were fixed in 2.5 % glutaraldehyde and then they were further processed for scanning and transmission electron microscopy. There was no difference in surface and internal structures of jumbo tiger prawn oocytes from four different regions. Oocytes were spherical in shape with 150-170 micrometer in diameter. The whole oocyte is covered by a sheath when the sheath was removed, the surface revealed evenly-dispersed pits each with central knobs. The ultrastructure of oocyte cytoplasm could be divided into two zones based on the organization of the organelles, namely; the cortex and the medulla. The cortical zone was narrow and contained numerous cortical granules, while the medulla was wider and had abundant electron-dense yolk granules. Both cortical and medullary zones surrounded the central cavity. Each oocyte were covered with flattened cells with long processes. Abundant atypical RER and free ribosome were observed among cortical and yolk granules. A few SER, mitochondria and lipid droplets were present.
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