养殖金乌贼卵子发生和卵巢发育的组织学观察

为了深入了解金乌贼(Sepia esculenta Hoyle)的生殖生理特性,本研究采用解剖学方法及组织切片技术,观察和描述了金乌贼卵巢形态和卵子各个时相结构特征及其变化规律。研究结果表明,金乌贼卵子发生过程的主要特征表现为,卵子成熟之前滤泡细胞一直存在且伴随着其结构变化,滤泡细胞解体与卵黄物质出现同步发生,卵黄物质从无到有再到大量积累直至充满整个卵母细胞,细胞核则随着滤泡细胞内折逐渐发生偏移直至最后消失。研究还发现金乌贼卵巢内卵子发生不同步且形态差异显著,未成熟的卵子粘连在卵巢基质上,依次环布于卵巢基质周围,越靠近中心,卵母细胞发育程度越低;成熟后的卵子游离在卵巢腔中,经过输卵管排出体外。根据卵巢内卵子的大小和形态、滤泡细胞形态及卵黄形成情况,将金乌贼卵子发生分为增殖期(卵原细胞期)、小生长期(无滤泡期,单层滤泡期,双层滤泡期)、大生长期(滤泡内折期,卵黄形成早期,卵黄形成晚期)、成熟期、退化吸收期共5个时期9个时相。卵巢发育分期则是以卵子时相为基础,根据卵巢的外观形态、性腺系数以及切面上优势卵子的时相,把卵巢分为Ⅰ~Ⅵ共6个时期。金乌贼卵巢发育和卵子发生的动态观察与描述,对丰富头足类繁殖生物学理论及提升人工繁殖技术都具有重要意义。

Histology of oogenesis and ovarian development in cultured Sepia esculenta

The golden cuttlefish (Sepia esculenta Hoyle) is one of the most important commercial species in China and Japan. In order to protect and restore cuttlefish resources, researchers have paid a lot of attention to the reproductive biology and artificial breeding techniques of cuttlefish. In the present study, both anatomic methods and tissue section techniques were used to describe the histological and morphological characteristics of oogenesis and ovary development in cuttlefish, in order to elucidate the reproductive physiology of golden cuttlefish. During the oogenesis of S. esculenta, follicular cells were always observed and underwent structural changes before oocyte maturation. The disintegration of follicular cells and the occurrence of yolk substances occurred synchronously. Egg yolk substances accumulated gradually until the oocytes were full and the follicular cells had disintegrated completely, and the nuclei gradually disappeared along with the follicular cells. Eggs were not synchronized and exhibited significantly variable morphology. Immature oocytes adhered to the ovarian matrix and circulated around the matrix of the ovary so that oocytes closer to the center were less developed than those further away. After maturation, the oocytes were free in the ovarian cavity and were discharged through the oviduct. According to the morphology of oocytes and follicular cells and vitellogenesis, the asynchronous oogenesis of S. esculenta could be categorized into five stages, with nine phases:proliferative stage (oogonia phase), small growth stage (free follicular cell phase, single follicular cell phase, and double follicular cell phase), large growth stage (follicle penetration phase, pre-vitellogenic phase, and late-vitellogenic phase), maturation stage, and resorbing stage. Meanwhile, the ovarian development cycle could be categorized into six stages (I-VI), according to ovary appearance and gonad index (GI) and dominant phase of oocytes. Understanding the development and oogenesis of S. esculenta is of great significance to the theory of cephalopod reproductive biology and improving artificial propagation technology.