The Site of Spermatozoon Entrance in the Unfertilized Egg of Discoglossus pictus (Anura): An Electron Microscope Study
The Site of Spermatozoon Entrance in the Unfertilized Egg of Discoglossus pictus (Anura): An Electron Microscope Study
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盘舌鱼（无尾）未受精卵精子进入部位：电子显微镜研究
DOI：
10.1095/biolreprod12.4.439
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发表时间：
1975
影响因子：
3.6
通讯作者：
C. Campanella
中科院分区：
文献类型：
--
作者：
C. Campanella
圆盘舌鱼的卵子有一个动物酒窝，一个位于动物半球极点的坑，这是精子唯一成功穿透的地方。对未受精卵表面的超微结构分析揭示了动物酒窝的独特特征。它们是：i)排列规则的指状微绒毛，由纤维束支撑，纤维束看起来像微管，周围有触角状的糖萼，存在于动物酒窝的表面。纤维的方向和分布表明，它们可能在维持动物酒窝的形状方面发挥重要作用：2)存在于动物酒窝外围细胞质中的颗粒，其特征与典型的无尾两栖动物皮质颗粒略有不同，在卵子的其余外围细胞质中不存在。这些颗粒在动物酒窝中的独特存在以及它们在受精时的明显丢失表明它们可能积极参与受精过程。刚产下的盘舌鱼(彩蛙)的卵在动物半球表现出凹陷(动物凹陷)，其中心部分内陷并形成动物凹陷。动物凹陷充满了形成动物塞子的胶状透镜状材料，它突出在鸡蛋的表面(Hibbard，1928)。鸡蛋还被四个不同化学成分的胶状信封覆盖。最里面的包膜由两层膜层E1和E2组成，并严格附着在鸡蛋表面，除了动物酒窝外，它们与鸡蛋表面被一种糖蛋白性质的物质分开(Ghiara，1960)。在第二次减数分裂中期停滞的细胞核位于动物酒窝底部的生殖区的皮质细胞质中。在动物酒窝水平的鸡蛋部分，特别是在其底部，人们可以清楚地区分垂直于鸡蛋表面的条纹(Hibbard，
The egg of Discoglossus pictus has an animal dimple, a pit located at the animal hemisphere pole, which is the only site successfully penetrated by the sperm. Ultrastructural analysis of the unfertilized egg surface reveals unique features characterizing the animal dimple. They are: I) regularly spaced, finger-like microvilli supported by bundles of fibers which appear to be microtubules and surrounded by antennular glycocalyx, present at the surface of the animal dimple. The orientation and distribution of the fibers suggest that they may play an essential role in maintenance of the shape of the animal dimple: 2) granules present in the peripheral cytoplasm of the animal dimple whose characteristics are somewhat different from those of the typical Anuran cortical granules and which are absent from the rest of the peripheral cytoplasm of the egg. The unique presence of these granules at the animal dimple and their apparent loss at the time of fertilization suggest that they might actively participate in the fertilization process. Freshly laid eggs of Discoglossus picius (painted frog) exhibit a depression (the animal depression) at the animal hemisphere whose center part is invaginated and forms the animal dimple. The animal depression is filled with a gelatinous lens-shaped material forming the animal plug, which protrudes at the surface of the egg (Hibbard, 1928). The eggs are further covered with four gelatinous envelopes with different chemical compositions. The innermost envelope is made up of two membranous layers E1 and E2 and strictly adheres to the egg surface, except over the animal dimple where they are separated from the egg surface by a substance of glycoprotein nature (Ghiara, 1960). The nucleus, arrested in metaphase of the 2nd meiotic division, is located in the cortical cytoplasm of the area germinativa which is the bottom of the animal dimple. In sections of eggs at the level of the animal dimple, and particularly at its basal portion, one can clearly distinguish striations which are perpendicular to the egg surface (Hibbard,