Ultrastructural studies on developing follicles of the spotted ray Torpedo marmorata
Ultrastructural studies on developing follicles of the spotted ray Torpedo marmorata
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DOI：
10.1002/mrd.1133
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发表时间：
2002-01-01
影响因子：
2.5
通讯作者：
Piero, A
中科院分区：
文献类型：
--
作者：
Prisco, M;Loredana, R;Piero, A
对亚成年和成年性成熟雌性的光和超微结构研究表明，在鱼雷鱼中，卵泡发生始于早期胚胎，并且成体的两个卵巢含有不同大小和形态的发育中的卵泡。最初，卵泡由小卵母细胞构成，周围环绕着单层鳞状卵泡细胞。该组织由基底层和更外部的卵泡膜完成，卵泡膜在这个阶段由胶原纤维网络组成。随着卵母细胞生长的继续，在卵黄发生前和卵黄发生期间，基底层和卵母细胞核的组织不会发生显着变化。事实上，基底层仍然是无细胞的，由混合在无定形基质中的原纤维构成；由于灯刷染色体和一两个大核仁，细胞核总是显示出延伸的染色质网络。相比之下，颗粒层（或滤泡上皮）、卵质和卵泡膜细胞发生显着变化。颗粒层显示出最相关的修饰，变得多层和多态性，以逐渐出现中间细胞和梨状样细胞，分别位于卵黄包膜旁边或跨越整个颗粒层。中间细胞的出现遵循小卵泡细胞和卵母细胞之间细胞间桥的出现，因此我们可以假设，与其他脊椎动物一样，小细胞一旦将其质膜与卵母细胞的质膜融合，就会分化为中间细胞，然后分化为梨状细胞。关于卵质，可以在卵黄发生前卵泡中观察到，其特征是存在含有糖原的中间液泡，而在卵黄发生卵泡中，其特征是卵黄球数量增加。卵泡膜也发生了显着的变化：最初，它由胶原纤维网络构成，但后来，可以识别出含有立方形细胞的最外层卵泡膜和含有扁平细胞的内部。讨论了卵泡不同成分在卵母细胞生长中的作用。摩尔。重现。开发。 61: 78-86, 2002。(C) 2002 Wiley-Liss, Inc.
Light and ultrastructural investigations on sub-adult and adult sexually mature females, demonstrates that in Torpedo marmorata folliculogenesis starts in the early embryo and that the two ovaries in the adult contain developing follicles of various sizes and morphology. Initially, the follicle is constituted by a small oocyte, surrounded by a single layer of squamous follicle cells. The organization is completed by a basal lamina and, more externally, by a theca, that at this stage is composed by a network of collagen fibers. As the oocyte growth goes on, during previtellogenesis and vitellogenesis, the organization of the basal lamina and of the oocyte nucleus does not change significantly. The basal lamina, infact, remains acellular and constituted by fibrils intermingled in an amorphous matrix; the nucleus always shows an extended network of chromatin due to the lampbrush chromosomes, and one or two large nucleoli. By contrast, the granulosa (or follicular epithelium), the ooplasm, and the theca cells significantly change. The granulosa shows the most relevant modifications becoming multi-layered and polymorphic for the progressive appearance of intermediate and pyriform-like cells, located respectively next to the vitelline envelope, or spanning the whole granulosa. The appearance of intermediate cells follows that of intercellular bridges between small follicle cells and the oocyte so that one can postulate that, as in other vertebrates, small cells differentiate into intermediate, and then pyriform-like cells, once they have fused their plasma membrane with that of the oocyte. Regarding the ooplasm, one can observe as in previtellogenic follicles, it is characterized by the presence of intermediate vacuoles containing glycogen, while in vitellogenic follicles by an increasing number of yolk globules. The theca also undergoes significant changes: initially, it is constituted by a network of collagen fibers, but later, an outermost theca esterna containing cuboidal cells and an interna, with flattened cells, can be recognized. The role of the different constituents of the ovarian follicle in the oocyte growth is discussed. Mol. Reprod. Dev. 61: 78-86, 2002. (C) 2002 Wiley-Liss, Inc.