Abstract：
The individual ovarian follicle of sturgeons (Acipenseriformes, Acipenseridae) contains an oocyte surrounded by follicular cells (FCs), basal lamina, and thecal cells. The late stages of the secondary growth of follicles (mid- and advanced vitellogenic) are not fully explained in Acipenseriformes. To explore and discuss the ultrastructure of oocytes, FCs, an egg envelope, and explain how micropylar cells differentiate and the canals of a multiple micropyle are formed, the samples of ovaries of the mature sterlet sturgeon Acipenser ruthenus were examined. The oocytes are polarized, the nucleus is located in the animal hemisphere, contains lampbrush chromosomes and multiple nucleoli. In the ooplasm three regions are present: a perinuclear (contains the mitochondria), an endoplasm (contains the lipid droplets and yolk platelets), and a periplasm (contains the cortical granules, melanosomes, endocytotic and exocytotic vesicles). The melanosomes in animal hemisphere form two concentric rings separated by a lighter region between them. The FCs are differentiated into bright and dark cells that are both translationally and secretory active. Diversification of FCs involves repeated and cytoskeleton-dependent change of shape. In the advanced follicles the FCs are diversified into micropylar, the animal and vegetal regions cells, and the cells that delaminated from the epithelium in the animal region. The egg envelope is present in the perioocytic space and consists of three layers: (1) an inner layer or vitelline envelope, (2) a middle layer, and (3) an outer layer. The inner layer consists of four sublayers: (a) a filamentous sublayer composed of filaments released from the oocytes, (b) a trabecular 1 sublayer and (c) a trabecular 2 sublayer named due to the sequence of the deposition, and composed of filaments, fibres and trabecules, (d) a homogeneous sublayer located between the trabecular 1 and trabecular 2 sublayers composed of filaments that adhere to each other closely. The middle layer contains two sublayers: a porous 1 and a porous 2 (composed of granular material) which are released by the oocyte and FCs. The outer layer consists of fibrillar material released by the FCs. The egg envelope is pierced by radial canals formed around the microvilli of the oocyte and the microvilli-like processes of FCs. A micropylar field in the egg envelope that covers the animal pole of the oocyte contains 1 - 4 micropylar canals. Micropylar cells are involved in their formation. The shape of these cells is icicle-like and the cytoplasm is differentiated into two regions (a basal and apical bearing a projection) equipped with different sets of organelles.
摘要：
st鱼的单个卵巢卵泡（酸性，Acipenseridae）包含一个被卵泡细胞（FC）包围的卵母细胞，基底层，和鞘细胞。卵泡次级生长的后期（中期和晚期卵黄形成）在Acipenserileformes中并未得到充分解释。探讨卵母细胞的超微结构,FC,一个鸡蛋信封,并解释了微小孔道细胞是如何分化和形成多个小孔的，检查了成熟的条状st鱼Acipenserruthenus的卵巢样本。卵母细胞是极化的,细胞核位于动物的半球,含有灯刷染色体和多个核仁。在卵质中存在三个区域：核周（包含线粒体），内质（包含脂滴和卵黄血小板），和周质（包含皮质颗粒，黑色素体，内吞和外吞囊泡）。动物半球中的黑色素体形成两个同心环，它们之间由较浅的区域隔开。FCs分化成既具有翻译活性又具有分泌活性的亮细胞和暗细胞。FC的多样化涉及形状的重复和细胞骨架依赖性变化。在晚期卵泡中，FCs多样化为微小幽门，动物和植物区域的细胞，以及从动物区域的上皮分层的细胞。卵包膜存在于周卵空间中，由三层组成：（1）内层或卵黄包膜，（2）中间层，和(3)外层。内层由四个子层组成：（a）由卵母细胞释放的细丝组成的丝状子层，（b）小梁1子层和（c）小梁2子层，由于沉积的顺序而命名，由细丝组成，纤维和小梁，(d)位于小梁1和小梁2子层之间的均匀子层,其由彼此紧密粘附的细丝组成。中间层包含由卵母细胞和FC释放的两个子层:多孔1和多孔2(由颗粒材料组成)。外层由FC释放的纤维状材料组成。卵包膜被围绕卵母细胞微绒毛和FC的微绒毛样过程形成的放射状管刺穿。卵包膜中覆盖卵母细胞动物极的微柱区包含1-4个微柱管。微孔细胞参与其形成。这些细胞的形状是冰囊状的，细胞质分化成两个区域（带有突起的基底和顶端），这些区域配备了不同的细胞器组。
