葛氏鲈塘艚卵子发生的组织学观察

采用组织切片技术系统观察和描述了葛氏鲈塘鱧（Perccottus glenii Dybowski）卵巢各时相卵母细胞的形态结构、特征及变化。卵巢切面显示：卵母细胞发育分为6个时相：第Ⅰ时相卵母细胞由处于原始分化阶段的卵原细胞构成;第Ⅱ时相卵母细胞进入滤泡细胞期,胞外形成滤泡细胞膜：第Ⅲ时相卵母细胞由质膜向核膜逐渐积累皮质液泡：第Ⅳ时相卵母细胞主要形成卵黄颗粒：第Ⅴ时相卵母细胞为成熟的卵子,胞内含有丰富的卵黄;第Ⅵ时相卵母细胞是未排出的处于退化吸收阶段的卵细胞,卵膜破裂,卵黄被吸收。根据卵巢切片及性腺系数变化推测葛氏鲈塘鱧属于一次产卵类型。     

凡纳滨对虾卵子发生的超微结构

利用透射电镜研究凡纳滨对虾卵子发生过程中细胞内部结构的变化。结果显示,卵原细胞结构简单,代谢水平低,核孔稀少,通过核周池来完成核、质之间的物质交换。卵黄发生前晚期和卵黄发生初期的卵母细胞变化显著：核膜凹凸不平,核仁数量多,核孔密集,大量核仁外排物经核孔输送到卵质中;卵质中胞器极为丰富和发达,代谢活性极强。卵黄发生旺盛期是卵黄大量形成的阶段,卵质边缘还呈辐射状排列了一圈椭圆形皮质棒,细胞出现微吞饮活动并形成卵黄膜。卵黄发生晚期卵质中充满了粗大的卵黄粒和脂滴,胞器锐减。另外,探讨了卵细胞内部结构的变化和卯黄形成的关系以及皮质棒的来源与功能。     

色林错裸鲤性腺发育的组织学研究

采用组织切片法,对西藏特有鱼类林错裸鲤的性腺发育、产卵时间和产卵类型等进行了研究。其性腺的发育可分为六个时期,卵母细胞的发育分为5个时相。在第2时相晚期到第3时相早期,卵母细胞中具有卵黄核和核仁物质外排现象,核仁排出的可能与核周的颗粒卵黄形成有关。第2时相到第4时相早期,核膜外侧具有一透明层。产卵后未提出的成熟卵粒通过颗粒细胞吸收和利用,已达性成熟年龄的个体并不是每年都参与繁殖活动,具有繁殖间隔现象。产卵时间始于4月上旬,持续到8月上旬。色林错裸鲤属于分次同步产卵类型。     

花䱻卵母细胞发育的组织学和超微结构观察

2015年7月至2017年10月在河南省驻马店宿鸭湖水库采集花?(Hemibarbus maculatus Bleeker)雌鱼样本190尾,体长7.12～32.21 cm,体重10.55～330.22 g,采用组织学和扫描电子显微镜技术观察了花?卵母细胞发育各时期的特征。结果表明,花?卵母细胞发育可分为5个时相,第I时相卵母细胞处于卵原细胞增殖阶段;第Ⅱ时相卵母细胞处于初级生长阶段,出现滤泡膜;第Ⅲ时相卵母细胞出现皮质液泡,细胞质膜之间形成放射带;第Ⅳ时相卵母细胞处于大生长后期,卵黄颗粒增多。电镜下观察发现放射带表面形成微孔状结构,核仁外排,可能与卵母细胞内营养物质积累有关;第Ⅴ时相卵母细胞中细胞核消失,卵母细胞发育为成熟卵子,与卵膜脱离,准备排卵。繁殖季节,花?卵巢成熟系数达到13.78%～17.04%。研究结果可为花?人工繁殖和育种工作提供参考。     

池养鲻的卵巢发育和卵子发生过程

通过卵巢切片的组织学分析揭示，幼鲻在土池养殖3个月后可见线状卵巢，大约5个月后卵原细胞进入第一次成熟分裂前期的双线期转变为早期初级卵母细胞。接着卵母细胞生发泡(核)和胞质体积增加，核质比从3．5：1减少至2：1。此后卵巢中卵母细胞停滞发育持续至养殖的第3年。在第3年卵巢切片看出卵母细胞进入脂肪泡时相，在第3年秋季进入卵黄发生时相。但在人工养殖条件下卵母细胞仅能发育到卵黄发生后期，即卵母细胞胞质充满卵黄颗粒，生发泡居中而不移位。这些结果对于用人工养殖鲻为亲鱼开展人工繁殖提供重要的科学依据。并讨论了卵子发生6个时相的生物学特点及其重要的细胞器在卵黄发生中可能的生理作用。     

长鳍吻卵巢发育组织学及周年变化的初步研究

采用常规解剖和组织学切片的方法,对长江上游宜宾江段长鳍吻卵巢发育、卵子发生以及成熟系数的周年变化进行了研究。研究结果表明,长鳍吻卵巢发育分为Ⅵ期,卵母细胞发育分为6个时相,第2时相中期出现卵黄核,2时相晚期迁移至皮质层破碎、消失;第3时相早期卵黄核消失位置开始出现卵黄泡,第3时相中后期放射带出现后卵黄颗粒开始积累;第5时相卵母细胞体积最大,胞径(1805±60.99)μm。卵巢成熟系数周年变化范围为0.78%~18.22%,一年内仅在4月份出现一个峰值,4—5月大部分卵巢处于Ⅳ、Ⅴ期,综合成熟系数测定和性腺组织学观察结果,初步推测长鳍吻繁殖期为3—5月,产卵盛期为4月上旬至5月上旬。     

四指马鲅卵巢发育和卵子发生的组织学观察

为了解四指马鲅（Eleutheronema tetradactylum）的卵巢发育和卵子发生过程，本研究运用组织切片HE染色方法对其卵巢发育的组织结构变化和卵子发生过程中各时相卵母细胞的结构进行观察。结果显示，四指马鲅卵巢为被膜型卵巢，紧贴中肾腹面，两支卵巢前端分离于后端融合，呈"Y"字形。卵子发生过程分可分为5个时相，在II时相中期卵母细胞周围开始出现滤泡细胞，II时相晚期形成单层滤泡细胞，直至III时相中期滤泡细胞层外形成鞘膜细胞层；卵黄核在II时相中期开始出现至III时相早期消失；卵黄泡在III时相早期的细胞核附近及胞质边缘出现；卵黄颗粒在III时相晚期开始出现于卵黄泡之间，并在IV时相早期填充卵黄泡，至IV时相晚期形成卵黄小板。卵巢发育过程分为6个时期，每个时期都存在不同时相的卵母细胞；V期卵巢的卵径呈双峰分布，分别在50.00~100.00 μm和300.00~350.00 μm区间出现峰值。四指马鲅卵巢发育模式为非同步发育-分批产卵类型。     

四川华鳊卵子发生的显微结构观察

为探究四川华鳊(Sinibrama taeniatus)卵子的发生规律,对其卵子发生进行了显微结构观察和描述。将卵子发生分为卵原细胞(Ⅰ时相)、单层滤泡时相(Ⅱ时相)、卵黄泡出现时相(Ⅲ时相)、卵黄充满时相(Ⅳ时相)和成熟卵子(Ⅴ时相) 5个时相。观察发现,四川华鳊卵原细胞存在2种形态,分别为早期卵原细胞和有丝分裂过程中的卵原细胞;同时将早期初级卵母细胞划入Ⅱ时相,此阶段细胞核膜边缘出现多个小核仁,将其作为小生长期开始的标志;Ⅲ时相卵黄泡出现,当卵黄泡积累至3～5层时,卵黄物质即开始积累,此时多以卵黄颗粒的形式存在;进入Ⅳ时相后,卵黄物质沉积形成卵黄小板,卵黄泡被挤压至卵周,形成皮层小泡,卵子成熟后,原皮层小泡所在区域呈块状或颗粒状,经苏木精-伊红(HE)染色后呈橘红色。     

对虾卵细胞的发生

用光镜和电镜观察了对虾(Penaneus orientalis Kishinouye)卵细胞的发生。结果为:1.卵母细胞核逐渐长大。核仁经历大量形成,颗粒部与原纤维部分离并在核膜下连成一片,以及颗粒部消散等过程。胞浆,早期游离核糖体多,而后内质网池多。在内质网池间出现卵黄球前体,后形成卵黄球。最后在胞浆的外周出现皮质棒。2.卵泡细胞逐渐伸展于卵母细胞间,将其完全分隔开。早期胞浆中多滑面内质网,而后为大量粗面内质网。     

孔雀鱼雌性生殖器官组织结构及卵子发生的研究

应用光镜技术研究了孔雀鱼（Poecilia reticulata）雌性生殖器官组织结构和卵子发生的特点,以期为孔雀鱼的良种繁育工作提供基础资料。结果表明,孔雀鱼雌性生殖器官由卵巢、卵子输送管和泄殖孔构成。卵子发生过程经历了6个时相：第Ⅰ时相主要为卵原细胞;第Ⅱ时相是处于小生长期的初级卵母细胞,形成生长环、卵黄核和单层扁平滤泡细胞膜;第Ⅲ时相是进入大生长期的初级卵母细胞,卵黄开始积累,形成2层滤泡细胞膜和2层卵包膜;第Ⅳ时相为发育晚期的初级卵母细胞,细胞发生了极化,卵包膜发育完善;第Ⅴ时相发育成熟,卵黄颗粒凝结呈块状,卵黄泡主要分布于细胞膜内缘,滤泡细胞膜萎缩;第Ⅵ时相是闭锁卵泡,被滤泡细胞消化和吸收转变为卵巢内结缔组织。     

Egg collection from hatchery-reared broodstock of spotted halibut Verasper variegatus treated with LHRH analog

The objective of this study is to establish a method for acquiring large quantities of high-quality eggs for artificial fertilization from hatchery-reared broodstock of spotted halibut Verasper variegatus. We estimated the optimum conditions for implantation of luteinizing hormone-releasing hormone analog (LHRHa) cholesterol pellet (LHRHa-CP) to induce ovulation from two experiments which focused on the dose and the timing combined with monitoring of oocyte development by ovarian cannulation. From the results of cannulation, vitellogenesis of hatchery-reared broodstock was suggested to occur normally, although final oocyte maturation was not initiated in the first clutch of oocytes. In late December, oocytes in the most advanced clutch still underwent vitellogenesis, having diameter of about 0.82?mm. LHRHa-CP implantation during this period had no remarkable effects, except for administration at high dose (100???g/kg). In contrast, in mid January, when oocyte diameter reached about 0.95?mm, ovulation occurred in most individuals, even at low dose (20???g/kg). In mid February atretic oocytes became remarkable and LHRHa-CP implantation showed much lower performance in terms of egg quality. The diameter of growing oocytes converged to about 0.95?mm, which was that of fully grown postvitellogenic oocytes. Thus, oocyte diameter is suggested to be an effective indicator to estimate the timing of LHRHa-CP implantation.     

Reproductive cycle and human chorionic gonadotropin-induced ovulation in hatchery reared Japanese catfish Silurus asotus

ABSTRACT:   The annual reproductive cycle, including the first maturity of ovarian development and plasma levels of testosterone (T) and estradiol-17β (E2), was examined in female Japanese catfish Silurus asotus reared under natural conditions. In addition, the possible period that final oocyte maturation and ovulation can be induced by human chorionic gonadotropin (hCG) injection were investigated. Results showed that female Japanese catfish matured 1 year after hatching under reared conditions. The beginning of vitellogenesis was in March and ovarian development and plasma T and E2 levels peaked in June. Thereafter, the gonadosomatic index gradually decreased to October and regression of oocytes at the tertiary yolk globule stage was observed. Female Japanese catfish could be induced to final oocyte maturation and ovulation by hCG treatment during the period from June to September. In addition, the fertilization rates were relatively high and stable during this period. These results suggest that yearling female Japanese catfish can be used as brood stock for seed production. This is the first study to investigate the annual reproductive cycle in Japanese catfish. These data will provide useful information regarding brood stock management and seed production.     

Diurnal rhythm of serum steroid hormone levels in the Japanese whiting,Sillago japonica,a daily-spawning teleost

Ovarian developmental stages and serum steroid hormone levels were examined at six different times of day (0100, 0600, 1000, 1300, 1600, 2000 h) in a marine teleost, the Japanese whiting Sillago japonica, which has an asynchronous-type ovary containing oocytes at various stages of development and spawns every day during a period ranging up to three months. The largest oocytes in the ovaries at the active vitellogenic or post-vitellogenic stages were found between 0100 and 1300 h. Oocyte maturation indicated by germinal vesicle breakdown (GVBD) occurred at 1600 h, and ovulated oocytes were observed in the ovaries collected at 2000 h. These processes were accompanied by a significant daily change in serum steroid hormone levels. The serum level of estradiol-17β showed a peak in fish with mature oocytes sampled at 1600 h. In these fish, the second-largest oocytes in the ovaries were at the initial stage of vigorous vitellogenesis, the secondary yolk stage. Therefore the highest level of serum estradiol-17β was considered to be due to the second-largest oocytes. Testosterone levels remained low and constant throughout the experimental period. The serum levels of 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-diOHprog) peaked at 1600 h at which time all fish had mature oocytes. These results indicate that the Japanese whiting possesses a diurnal rhythm of oocyte development including vitellogenesis, oocyte maturation and ovulation, and further suggest that daily cycles in oocyte growth and maturation which simultaneously take place in an ovary are regulated by diurnal secretions of estradiol-17β and the maturation-inducing steroid, 17α,20β-diOHprog.     

半滑舌鳎卵巢发育的组织学和形态数量特征研究

采用组织学方法系统研究了人工养殖条件下半滑舌鳎亲鱼卵巢的组织发育周年变化特征.结果表明,卵母细胞发育可分为6个时相,卵巢发育分为6期.卵巢不同发育时期都由不同类型的卵母细胞组成,半滑舌鳎为非同步分批多次产卵类型.周年发育过程中,6月龄前的鱼卵巢发育处于第Ⅰ期;9～12月龄卵巢可发育至第Ⅱ期;12月龄半滑舌鳎性腺可发育达到Ⅲ期,并一直保持至24月龄.3龄雌鱼达到性成熟,卵巢可发育至第Ⅳ期;随着水温和光周期的调控,卵巢发育进入成熟期(Ⅴ期),发生水合现象是卵母细胞成熟并准备排卵的信号;产卵结束后卵巢退化至第Ⅵ期,排出的卵母细胞退化吸收,以Ⅲ期卵巢越冬后,卵巢退化至Ⅱ期并持续至下一个繁殖周期.人工养殖条件下,卵巢内存在卵母细胞闭锁现象.性腺周年发育过程中,性腺指数(GSI)在性腺达到成熟期时达到峰值,产卵结束后性腺快速退化,GSI值各月份差异显著(P<0.05),亲鱼性腺重量在卵巢发育成熟过程中一直处于生长状态.亲鱼肝脏指数(HSI)在产卵前7～8月份(性腺达到成熟期前30 d左右)达到最大,表明7～8月份是性腺进行卵子发育、卵黄能量储备的重要时期,亲鱼在产卵前通过积极摄食储备体内能量,肝脏在卵母细胞卵黄积累方面具有重要的生理作用.肥满度(CF)值在繁殖盛期10～11月份达到最大,表现出与GSI类似的变化趋势.     

Changes in the expression of pituitary gonadotropin subunits during reproductive cycle of multiple spawning female chub mackerel Scomber japonicus

The endocrine regulation of reproduction in a multiple spawning fish with an asynchronous-type ovary remains largely unknown. The objectives of this study were to monitor changes in the mRNA expression of three gonadotropin (GtH) subunits (GPα, FSHβ, and LHβ) during the reproductive cycle of the female chub mackerel Scomber japonicus. Cloning and subsequent sequence analysis revealed that the cDNAs of chub mackerel GPα, FSHβ, and LHβ were 658, 535, and 599 nucleotides in length and encoded 117, 115, and 147 amino acids, respectively. We applied a quantitative real-time PCR assay to quantify the mRNA expression levels of these GtH subunits. During the seasonal reproductive cycle, FSHβ mRNA levels remained high during the vitellogenic stages, while GPα and LHβ mRNA levels peaked at the end of vitellogenesis. The expression of all three GtH subunits decreased during the post-spawning period. These results suggest that follicle-stimulating hormone (FSH) is involved in vitellogenesis, while luteinizing hormone (LH) functions during final oocyte maturation (FOM). Both GPα and FSHβ mRNA levels remained high during the FOM stages of the spawning cycle and increased further just after spawning. Thus, FSH synthesis may be strongly activated just after spawning to accelerate vitellogenesis in preparation for the next spawning. Alternatively, LHβ mRNA levels declined during hydration and then increased after ovulation. This study demonstrates that chub mackerel are a good model for investigating GtH functions in multiple spawning fish.     

Oogenesis and lipids in gonad and liver of daubed shanny (Leptoclinus maculatus) females from Svalbard waters

Oocyte and liver histomorphology of the daubed shanny (Leptoclinus maculatus) from Isfjorden and Kongsfjorden in Svalbard were investigated during three Arctic seasons: summer (July), autumn (October) and winter (April). Three oocyte developmental phases were observed: primary growth phase, secondary growth phase and maturation phase. We observed four different developmental stages: (1) perinucleolus stage with cortical alveolus formation, (2) lipid droplets formation, (3) vitellogenesis stage and (4) maturation. Late maturation stage of oocytes in the ovaries was from the autumn season. Females accumulated lipids in liver (up to 35.2?% dw) and deposited large amounts of lipids into gonads (up to 52.2?% dw) during maturation. Lipid classes in female gonads changed seasonally, with relative increase in cholesterol during summer and depletion of storage lipids (triacylglycerols and wax esters/cholesterol esters) during the winter. Lipid composition in liver changed during oocyte development and spawning, as neutral lipids were transferred to developing oocytes during summer to autumn. During winter, storage lipids were depleted during starvation. Based on the increase in gonadosomatic index (GSI) with length and observed maturation stages, females seem to mature at a length of about 125-130?mm. The GSI and hepatosomatic index of large females sampled in autumn (September-October) were significantly higher than for females in late winter (April) and spring (May). These results indicate that spawning takes place during winter in Isfjorden and that energy reserves stored in the liver are utilized by females during gonadal development and reproduction.     

Immunoreactive changes in pituitary FSH and LH cells during seasonal reproductive and spawning cycles of female chub mackerel <Emphasis Type="Italic">Scomber japonicus</Emphasis>

The physiological functions of pituitary gonadotropins (GtHs) are well established in higher vertebrates, whereas those in teleosts are still poorly understood. To describe the role of GtHs during gonadal development of female chub mackerel Scomber japonicus, changes in follicle-stimulating hormone (FSH) and luteinizing hormone (LH) cells were investigated immunohistochemically during the seasonal reproductive and spawning cycles. FSH and LH cells were identified in the different cell types of the proximal pars distalis (PPD); FSH cells were located in the central PPD, whereas LH cells were localized along the border of the pars intermedia. To examine changes in FSH and LH cells, the percentage of FSH or LH cell-occupying area in the PPD was evaluated and represented as FSHβ-immunoreactive (ir) or LHβ-ir levels, respectively. FSHβ-ir levels increased significantly from immature to the completion of vitellogenesis, whereas LHβ-ir levels were maintained at high levels from early vitellogenesis to post-spawning. During the spawning cycle, which consisted of four stages from just after spawning to the next oocyte maturation, both FSHβ-ir and LHβ-ir levels showed no significant changes among different stages; however, LHβ-ir levels remained relatively high, and FSHβ-ir levels were constantly low. These results suggest that both FSH and LH may be involved in vitellogenesis and LH may act at final oocyte maturation in female chub mackerel, although the role of FSH during the spawning cycle is still unclear.     

Effects of Thyroxin and Domperidone on Oocyte Maturation and Spawning Performances in the Rabbit Fish,Siganus guttatus

Thyroxin (T₄) is proven to have various functions in fish reproduction. In this study, we investigated oocyte maturation and spawning performance in the rabbit fish, Siganus guttatus, orally exposed to different doses of T₄ (0.05, 0.25, and 0.5 mg/kg fish) during vitellogenesis. No statistically significant differences of reproductive characteristics were observed among the treatments. However, the group that was exposed to the dose of 0.5 mg/kg spawned after receiving a hormone injection. The findings suggest that feeding T₄ during vitellogenesis did not advance oocyte maturation, but probably could induce spawning in rabbit fish. In a separate experiment, we investigated the effects of orally administered domperidone (DOM) on reproductive performances of the female rabbit fish. The study showed that oral administration of DOM during the early stages of the reproductive cycle had no significant effects on oocyte maturation and spawning performance. Overall, these findings suggest that DOM may not be needed for the induction of maturation and spawning of this species under aquaculture conditions. These practical investigations were conducted with a view to attempt reducing drug use, production costs, and support sustainable aquaculture.     

细鳞鱼的卵黄发生

从发育生物学—卵黄发生角度,通过光镜和透射电镜对细鳞鱼(Brachymystax lenok)卵黄发生进行观察。结果表明,细鳞鱼的卵黄发生主要集中在初级卵母细胞阶段完成,可分为4个特征时期:初级生长期,皮质泡期,卵黄积累期,卵黄积累完成期。当卵母细胞进入初级生长早期,卵子发生特征物——类核周体出现;进入皮质泡期,其主要特征是皮质泡、卵黄外膜和巴尔比亚尼体结构;处于卵黄积累期,位于其外周细胞质附近会出现卵黄颗粒;进入卵黄积累完成期,卵黄颗粒不断融合增大,占据细胞绝大部分。以上结果为细鳞鱼的卵巢发育分期提供了理论基础,并深入探讨其发育的规律性、特殊性和复杂性,从而指导细鳞鱼的人工繁殖、选育种工作及野生群体的资源保护和合理利用。     

Effects of accelerated photoperiod regimes on the reproductive cycle of the female rainbow trout: II Seasonal variations of plasma gonadotropins (GTH I and GTH II) levels correlated with ovarian follicle growth and egg size

Female rainbow trout were exposed over their second reproductive cycle to a simulated natural photoperiod (control group) and to two accelerated photoperiod regimes (S9 and S6 groups). Early spawning was achieved in both accelerated groups, coupled, however, with a reduction of mean egg size. To investigate this reduction of egg size, circulating levels of GTHs and two indices of ovarian growth (gonadosomatic index and follicle diameter) were regularly measured in association with histological studies of structural changes in ovarian follicles. Regardless of the photoperiod regime, the seasonal profile of plasma GTH I levels appeared to be multiphasic. The successive transient elevations in GTH I levels appeared to be connected with the initiation of ovarian growth and vitellogenesis and also, with the synchronization of the late stages of maturation and ovulation. In contrast, the seasonal profile of plasma GTH II levels was monophasic, with a single peak at ovulation, confirming that GTH II is not associated with ovarian growth but promotes gamete maturation and release. Our results demonstrate that the reduction of egg size cannot be due to a deficient secretion of GTH I in plasma, since GTH I levels were much higher during vitellogenesis in both accelerated groups, but rather to an alteration of ovarian follicle growth during the late stages of vitellogenesis. Finally, the early and middle stages of ovarian growth appeared to be photosensitive periods, whereas the late stages were less so, and appeared to be controlled rather by an endogenous biological clock synchronized by the photoperiod.