Temereva Elena N
Biological Faculty, Department of Invertebrate Zoology, Moscow State University, Russia, Moscow.
J Morphol. 2018 Feb;279(2):199-215. doi: 10.1002/jmor.20765. Epub 2017 Oct 27.
The study of gametogenesis is useful for phylogenetic analysis and can also provide insight into the physiology and biology of species. This report describes oogenesis in the Phoronis embryolabi, a newly described species, which has an unusual type of development, that is, a viviparity of larvae. Phoronid oogonia are described here for the first time. Yolk formation is autoheterosynthetic. Heterosynthesis occurs in the peripheral cytoplasm via fusion of endocytosic vesicles. Simultaneously, the yolk is formed autosynthetically by rough endoplasmic reticulum in the central cytoplasm. Each developing oocyte is surrounded by the follicle of vasoperitoneal cells, whose cytoplasm is filled with glycogen particles and various inclusions. Cytoplasmic bridges connect developing oocytes and vasoperitoneal cells. These bridges and the presence of the numerous glycogen particles in the vasoperitoneal cells suggest that nutrients are transported from the follicle to oocytes. Phoronis embryolabi is just the second phoronid species in which the ultrastructure of oogenesis has been studied, and I discuss the data obtained comparing them with those in Phoronopsis harmeri. Finally, I discuss the distribution of reproductive patterns across both, molecular and morphological phylogenetic trees in Phoronida proving that parental care has evolved independently several times in this phylum.
配子发生的研究对于系统发育分析很有用，还能为物种的生理学和生物学提供见解。本报告描述了新描述的物种胚胎海豆芽（Phoronis embryolabi）的卵子发生，该物种具有不寻常的发育类型，即幼虫胎生。本文首次描述了海豆芽类的卵原细胞。卵黄形成是自体异质合成的。异质合成通过内吞小泡在周边细胞质中融合而发生。同时，卵黄由中央细胞质中的粗面内质网自体合成形成。每个发育中的卵母细胞都被血管腹膜细胞的卵泡包围，其细胞质中充满糖原颗粒和各种内含物。细胞质桥连接发育中的卵母细胞和血管腹膜细胞。这些桥以及血管腹膜细胞中大量糖原颗粒的存在表明营养物质从卵泡运输到卵母细胞。胚胎海豆芽是第二个对卵子发生超微结构进行研究的海豆芽类物种，我将所获得的数据与哈氏海豆芽（Phoronopsis harmeri）的数据进行比较并加以讨论。最后，我讨论了海豆芽类在分子和形态系统发育树上繁殖模式的分布，证明亲代抚育在该门中已经独立进化了好几次。
