Zelazowska Monika, Kilarski Wincenty
Department of Systematic Zoology, Institute of Zoology, Jagiellonian University, R. Ingardena 6, 30-060 Kraków, Poland.
Cell Tissue Res. 2009 Mar;335(3):585-91. doi: 10.1007/s00441-007-0459-6. Epub 2007 Sep 18.
The ovary of paddlefish and sturgeons (Acipenseriformes) is composed of discrete units: the ovarian nests and ovarian follicles. The ovarian nests comprise oogonia and numerous early dictyotene oocytes surrounded by somatic prefollicular cells. Each ovarian follicle consists of a spherical oocyte and a layer of follicular cells situated on a thick basal lamina, encompassed by thecal cells. The cytoplasm of previtellogenic oocytes is differentiated into two distinct zones: the homogeneous and granular zones. The homogeneous cytoplasm is organelle-free, whereas the granular cytoplasm contains numerous organelles, including mitochondria and lipid droplets. We have analyzed the cytoplasm of early dictyotene and previtellogenic oocytes ultrastructurally and histologically. In the cytoplasm of early dictyotene oocytes, two morphologically different types of mitochondria can be distinguished: (1) with well-developed cristae and (2) with distorted and fused cristae. In previtellogenic oocytes, the mitochondria of the second type show various stages of cristae distortion; they contain and release material morphologically similar to that of lipid droplets and eventually degenerate. This process of mitochondrial transformation is accompanied by an accumulation of lipid droplets that form a single large accumulation (lipid body) located in the vicinity of the oocyte nucleus (germinal vesicle). The lipid body eventually disperses in the oocyte center. The possible participation of these mitochondria in the formation of oocyte lipid droplets is discussed.
匙吻鲟和鲟鱼（鲟形目）的卵巢由离散单元组成：卵巢巢和卵巢滤泡。卵巢巢由卵原细胞和众多被体细胞前滤泡细胞包围的早期双线期卵母细胞组成。每个卵巢滤泡由一个球形卵母细胞和一层位于厚基膜上的滤泡细胞组成，被膜细胞包围。卵黄发生前卵母细胞的细胞质分化为两个不同的区域：均匀区和颗粒区。均匀细胞质不含细胞器，而颗粒细胞质含有众多细胞器，包括线粒体和脂滴。我们对早期双线期和卵黄发生前卵母细胞的细胞质进行了超微结构和组织学分析。在早期双线期卵母细胞的细胞质中，可以区分出两种形态不同的线粒体类型：（1）嵴发达的和（2）嵴扭曲且融合的。在卵黄发生前卵母细胞中，第二种类型的线粒体显示出嵴扭曲的不同阶段；它们含有并释放出形态上与脂滴相似的物质，最终退化。这种线粒体转化过程伴随着脂滴的积累，这些脂滴形成一个位于卵母细胞核（生发泡）附近的单一大聚集体（脂体）。脂体最终在卵母细胞中心分散。讨论了这些线粒体在卵母细胞脂滴形成中的可能作用。
