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首页> 外文期刊>Cell biology international. >Ultrastructure of the ovary and oogenesis in the flatworm Prosthiostomum siphunculus (Polycladida, Cotylea)
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Ultrastructure of the ovary and oogenesis in the flatworm Prosthiostomum siphunculus (Polycladida, Cotylea)

机译：卵巢的超微结构和扁平虫Prosthoostomum siphunculus（Polycladida，Cotylea）中的卵巢

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摘要

Based on light and electron microscopy observations, oogenesis in the cotylean polyclad Prosthiostomum siphunculus was investigated for the first time. The numerous ovarian follicles are dispersed essentially in the dorsal parenchyma. In the follicles, a ventral germinative zone with undifferentiated germs cells of different sizes and a dorsal growth zone with larger growing and abortive oocytes are present. The oogenesis could be subdivided into four stages: (1) Oogonia with a dark nucleus and a dark, ribosome-rich cytoplasm. (2) Early oocyte stage, represented by relatively small cells (10 mm in diameter), a cytoplasm showing some mitochondria and some endoplasmic reticula. (3) Previtellogenic stage, with a decrease of the nucleo-cytoplasmic ratio due to the remarkable increase in ooplasm volume. Immature eggshell globules are observed. (4) Vitellogenic stage, including early vitellogenic ovarian stage, in which a second type of globule (inclusion globule) is formed, and a late vitellogenic uterine stage, in which the inclusion globules are not present anymore. The mature eggshell globules form a peripheral layer under the cell membrane. Eggshell and inclusion globules were analyzed with electron energy loss spectroscopy, electron spectroscopic imaging, protease treatment, and with periodic acid thiocarbohydracide silver proteinate to detect polysaccharides. Chromatoid bodies are present in all four stages. For the first time in a flatworm, we provide evidence that accessory cells, forming a tunica around the ovarian follicles, are epithelial or epithelium-like and likely contribute nutrients for the growth of the oocytes.
机译：基于光和电子显微镜观察，第一次研究了胞浆聚合物Prosthoostomumumumumumumumumumumumumumumumumumumumumumumumumumumumumum。许多卵巢卵泡基本上分散在背侧薄壁症中。在卵泡中，存在具有不同尺寸的未分化细胞细胞和具有较大生长和中断卵母细胞的背体生长区的腹侧发芽区。 OECOORYESS可以细分为四个阶段：（1）卵黄素，具有深色核和富含核糖瘤的细胞质。 （2）早期的卵母细胞阶段，由相对较小的细胞（直径为10mm），一种表现出一些线粒体和一些内质网的细胞质。 （3）预介质阶段，由于O质量显着增加，核 - 细胞质比率降低。观察到不成熟的蛋壳球。 （4）培体阶段，包括早期vitellogal卵巢阶段，其中形成了第二种类型的小球（包含球丸），并且是晚期vetellogens子宫阶段，其中包含球状球体不再存在。成熟的蛋壳小球在细胞膜下形成外围层。用电子能损光谱，电子光谱成像，蛋白酶处理和用碘酸硫代芳烃银蛋白蛋白分析蛋壳和包容球，以检测多糖。染色片体在所有四个阶段存在。首次在扁平虫中，我们提供了一种证据，即在卵巢卵泡周围形成牙龈的辅助细胞是上皮或上皮，并且可能有助于卵母细胞生长的营养素。

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