Department of Developmental Biology and Morphology of Invertebrates, Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University, Kraków, Poland.
Laboratory of Germ Cells in the Research Institute of Fish Culture and Hydrobiology, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Faculty of Fisheries and Protection of Waters, University of South Bohemia in České Budějovice, Vodňany, Czechia.
J Morphol. 2023 Sep;284(9):e21631. doi: 10.1002/jmor.21631.
Ovarian follicles of sterlets (Acipenser ruthenus) are composed of a single oocyte surrounded by follicular cells (FCs), basal lamina, and thecal cells. Previtellogenic oocytes are polarized. Homogeneous ooplasm (contains ribosomes) and granular ooplasm (comprises nuage aggregations of nuclear origin, rough endoplasmic reticulum (RER), Golgi complexes, ribosomes, and mitochondria) are distinguished. Granular ooplasm is initially located near the nucleus, contacts the plasma membrane of the oocyte (oolemma) and forms a thin layer underneath its entire perimeter. Next, a ring that surrounds the nucleus is formed and sends strands directed toward the oolemma. The lipid body composed of lipid droplets forms adjacent to this ring. Later, the granular ooplasm and strands enlarge toward the oolemma, lipid body disperses, and homogeneous ooplasm is no longer present. A thin cortical ooplasm is formed underneath the oolemma and does not contain any organelles. The oocyte nucleus moves to the center. The nucleoplasm contains lampbrush chromosomes, nuclear bodies, and multiple nucleoli. Early vitellogenic oocytes are polarized, too. Three regions in the ooplasm are distinguished: the perinuclear (contains lipid droplets near the nuclear envelope), the endoplasm (contains yolk platelets and lipid droplets), and the periplasm (contains yolk spheres, pigment granules, and microtubules). In all these regions the RER, Golgi complexes, nuage, and mitochondria are present. Micropinocytotic vesicles, Golgi vesicles and precursors of the internal layer of the egg envelope are in the cortical ooplasm. Some FCs delaminate from the follicular epithelium, degenerate and vesicles are released into the perioocytic space. They may contain precursors of egg envelope and may be involved in "cell-cell" communication. The egg envelope (zona radiata, zona pellucida) is made up of three layers: the vitelline envelope (inner layer), the middle layer, and the outer layer. In its deposition, both the oocyte and FCs are engaged.
鲟鱼（Acipenser ruthenus）的卵巢卵泡由一个被卵泡细胞（FCs）、基底膜和膜细胞包围的单个卵母细胞组成。卵母细胞在卵黄发生前是极化的。均匀的卵质（包含核糖体）和颗粒状卵质（由核起源的核质凝聚物、粗面内质网（RER）、高尔基复合体、核糖体和线粒体组成）是有区别的。颗粒状卵质最初位于核附近，与卵母细胞的质膜（卵黄膜）接触，并在其整个周边下形成一层薄的层。接下来，形成一个环绕核的环，并向卵黄膜发出丝。由脂滴组成的脂体形成在这个环的旁边。后来，颗粒状卵质和丝状物向卵黄膜增大，脂体分散，均匀的卵质不再存在。在卵黄膜下形成一层薄的皮质卵质，其中不包含任何细胞器。卵母细胞核移动到中心。核质包含灯刷染色体、核体和多个核仁。早期卵黄发生的卵母细胞也是极化的。卵质中区分出三个区域：核周质（靠近核膜的核周质含有脂滴）、内质（含有卵黄小板和脂滴）和周质（含有卵黄球、色素颗粒和微管）。在所有这些区域都存在 RER、高尔基复合体、核质凝聚物和线粒体。皮质卵质中有微吞噬泡、高尔基小泡和卵膜内层的前体。一些 FCs 从滤泡上皮细胞分离、退化并释放小泡到周质间隙中。它们可能含有卵膜前体，并可能参与“细胞-细胞”通讯。卵膜（放射冠、透明带）由三层组成：卵黄膜（内层）、中层和外层。在卵膜的沉积过程中，卵母细胞和 FCs 都参与其中。
