三疣梭子蟹精卵相互作用的扫描电镜观察

应用扫描电镜技术观察了三疣梭子蟹的精卵相互作用。未受精成熟卵表面较光滑、无受精孔,但有许多微孔。成熟卵外被卵膜,内为卵母细胞。在卵自然产出后,精子迅速发生顶体反应使顶体囊外翻并压入卵膜,而核仍留于卵膜外,核辐射臂不收缩且仍附着于卵膜上。三疣梭子蟹为多精着卵和多精入卵膜。精子外翻顶体囊压入卵膜后,核辐射臂陆续回缩直至消失。作用于顶体丝上的卵母细胞主动拖精作用对入卵膜精子的进一步入卵、受精至关重要,环状卵膜突起的向心伸展也有一定的协助作用。探讨了着卵精子的顶体反应、精子入卵膜的机制及卵子在精子入卵过程中的作用     

花鲢卵球受精的细胞学研究

花鲢卵球属端黄卵,局部分裂。正常情况下,为单精虫受精;接受精虫的适当时期,从细胞核的标帜来说,是卵母细胞第二次成熟分裂中期。在排离卵巢的成熟卵母细胞上,有精孔、精孔细胞以及精孔细胞和卵母细胞之间的通路。精虫是经过精孔细胞进入卵球的。在26-27℃时,受精5-10分钟,精虫头部逐渐核化,星光发展,卵球第二次成熟分裂进入后期和末期,皮质小泡大量外排;10-15分钟,雌雄原核形成,精虫星光扩大,并移向胚盘中央区域,皮质小泡已排除殆尽;15—20分钟,雌雄原核在胚盘中央区接合,一对新发展的子星光出现;20—25分钟,第一次胚胎分裂图形建成;30分钟左右,卵裂开始;续后的分裂,大概每次间隔10分钟。本文比较分析了花鲢、白鲢、金鱼、鳊鱼和草鱼五种鲤科鱼类的受精过程,为它们之间杂交的可能性和困难性,提供了实验依据。     

花鲢卵球受精的细胞学研究

花鲢卵球属端黄卵,局部分裂。正常情况下,为单精虫受精;接受精虫的适当时期,从细胞核的标帜来说,是卵母细胞第二次成熟分裂中期。在排离卵巢的成熟卵母细胞上,有精孔、精孔细胞以及精孔细胞和卵母细胞之间的通路。精虫是经过精孔细胞进入卵球的。在26—27℃时,受精5—10分钟,精虫头部逐渐核化,星光发展,卵球第二次成熟分裂进入后期和末期,皮质小泡大量外排;10—15分钟,雌雄原核形成,精虫星光扩大,并移向胚盘中央区域,皮质小泡已排除殆尽;15—20分钟,雌雄原核在胚盘中央区接合,一对新发展的子星光出现;20—25分钟,第一次胚胎分裂图形建成;30分钟左右,卵裂开始;续后的分裂,大概每次间隔10分钟。本文比较分析了花鲢、白鲢、金鱼、鳊鱼和草鱼五种鲤科鱼类的受精过程,为它们之间杂交的可能性和困难性,提供了实验依据。       

黄颡鱼受精早期精子入卵扫描电镜观察

用扫描电镜对黄颡鱼(Pseudobagrus fulvidraco)成熟精、卵及授精早期精子入卵过程进行了观察。成熟精子为鞭毛型形态,全长为11·2～12·4μm,头部直径1·1～1·3μm,鞭毛长10·0～11·3μm。成熟的黄颡鱼卵呈圆形,具单一受精孔,卵膜上以受精孔为中心分布有无数辐射状沟嵴。授精前,受精孔暴露在外面;授精2s时,受精孔被纤维状物质覆盖,之后大量精子很快黏附在覆盖物上;至授精10s,漏斗状受精孔又暴露出来。黄颡鱼在授精10s～1min内完成精子入卵过程,可观察到几乎所有样品的精孔区出现一圈环状隆起。大量精子处于隆起外侧,只有少数越过隆起到达受精孔前庭。授精1·5min,精孔区的隆起变成两圈,精子鞭毛解体。授精3min,可见迟到的精子被挡在外面。授精5min,精孔区的精子头部解体,受精孔几乎被分泌物覆盖,受精塞清晰可见。至授精20min,精子几乎全部解体。讨论了精子入卵的动力作用、精卵识别和单精受精机制。     

泥鳅精子入卵的动力作用

在扫描电镜下,泥鳅成熟卵卵膜孔外围呈现完整的左涡旋状结构,受精时精子是顺着涡旋的流线进入卵膜孔。涡旋纹理接近对数螺线。本文分析了真骨鱼类的受精因素,除已知的化学因素外,还存在物理因素。也讨论了泥鳅成熟卵卵膜孔形态形成的必然性。     

团头鲂成熟卵的超微结构和X射线微区分析研究

本文应用扫描电镜、透射电镜及X射线微分析技术,对团头鲂成熟卵的超微结构和离子元素含量进行了研究.结果表明,在团头鲂成熟卵的卵膜上具有许多卵膜孔,胞质内有丰富的管状嵴线粒体和游离核糖体;在质膜下的皮质区内有皮质小泡、微管和微丝结构.卵的表面含有Na、Mg、Al,Si、S、Cl、K和Ca,含量分别为6.65±0.47,0.39±0.06,5.51±0.83,0.51±0.01,76.41±0.94,9.24±1.39,0.71±0.24和0.96±0.05.卵的胞质内含有Na、Mg、Si、P、S、Cl、K、Ca和Fe,其含量分别为10.26±0.15,3.04±0.12,19.48±1.23,1.17±0.32,13.42±1.59,14.83±2.32,20.26±3.15,10.02±1.69和7.52±1.83.     

普通针毛蕨颈卵器和卵的发育

蕨类植物卵发生是有性生殖研究的重要内容。真水龙骨类II的卵发生尚无人研究, 本文对该类群中的普通针毛蕨(Macrothelypteris torresiana)卵发生过程进行了光镜和透射电镜研究。结果显示: 卵细胞刚形成时, 与腹沟细胞紧密相连, 随着卵进一步发育, 卵细胞和腹沟细胞之间逐渐形成分离腔, 但孔区处卵细胞和腹沟细胞始终相连。随后, 卵细胞上表面有不定型物质堆积在质膜外, 形成一层加厚的卵膜, 孔区处没有卵膜覆盖的位置最后形成受精孔。在卵发育后期, 卵细胞核变得不规则, 近成熟时卵核产生大量核外突。卵发育过程中卵膜的出现、受精孔的产生以及核外突等特征, 与进化的真水龙骨类中其他蕨类植物的卵发生研究结果相似, 与薄囊蕨类中原始基部类群的卵发生现象有显著差别。由此可见, 普通针毛蕨属于进化类型。依据卵发生中卵膜和受精孔等特征推测原始薄囊蕨类经过里白类、桫椤类, 最终演化为水龙骨类。     

大银鱼卵膜孔结构的电镜观察

扫描电镜下，大银鱼成熟卵卵膜孔区域呈现奇异的放射沟脊状结构。在授精开始的３０秒内，测得卵膜附近约８６％的精子沿着凹沟进入精孔管；还拍摄到了通过卵孔中心的纵切面映象，通过电子计算机模拟，验证了卵膜孔的这种结构，为精子的云集和进入精孔管所提供有利条件，从而，于泥鳅之后又发现了一种真骨鱼，其精子入卵除化学因素外，还存在着不容忽视的机械动力因素。     

家养鱼类受精生物学的研究——Ⅱ．几种淡水鱼类成熟卵球的精孔器与精子入卵通路的光镜与扫描电镜观察

作者对我国四种淡水养殖鱼类——团头鲂、草鱼、白鲢和花鲢卵球的精孔器作了光学显微镜和扫描电子显微镜的比较描述,在扫描电子显微镜下观察到这几种鱼类的精子均直接经精孔器前庭穿过精孔管进入卵内,并对精孔细胞、受精孔与精子入卵的关系以及精孔的位置进行了讨论。     

家养鱼类受精生物学的研究 Ⅱ.几种淡水鱼类成熟卵球的精孔器与精子入卵通路的光镜与扫描电镜观察

作者对我国四种淡水养殖鱼类——团头鲂、草鱼、白鲢和花鲢卵球的精孔器作了光学显微镜和扫描电子显微镜的比较描述,在扫描电子显微镜下观察到这几种鱼类的精子均直接经精孔器前庭穿过精孔管进入卵内,并对精孔细胞、受精孔与精子入卵的关系以及精孔的位置进行了讨论。       

金鱼精子入卵过程的扫描电镜观察

本文采用扫描电镜观察了金鱼(Carassius auratus)卵壳膜(chorion)表面结构和精子入卵过程。在壳膜的卵膜孔(micropyle)区有5—10条沟和嵴。位于精孔管下面,卵的质膜为一束较长的微绒毛组成的精子穿入部(sperm entry site)。授精5s,精子头的顶部已附着于精子穿入部,随即两者的质膜发生融合,而围于精子头部四周的微绒毛迅速伸长形成一受精锥,它不断将精子头部包裹。授精110s,精子的头部和颈部已完全进入卵内,受精锥本身也渐趋消失,但精子尾部仍平躺于卵的表面。皮层小泡是在授精30s后才开始破裂并释放其内含物,导致卵子表面呈蜂窝状,并在无膜内表面附着了大量球状物。     

Closure of the micropyle during embryonic development of some pelagic fish eggs

The fine structure of the egg envelope and micropyle was studied in unfertilized and developing eggs of the flounder Paralichthys olivaceus (Temminck & Schlegel), the Alaska pollack Theragra chalcogramma (Pallas), the Japanese tilefish Branchiostegus japonicus (Houttuyn) and the porgy Pagrus major (Temminck & Schlegel). The outer envelope surface of the unfertilized egg was wrinkled, while the inner surface was folded. The micropyle of the unfertilized egg consisted of a shallow vestibule and a distinct canal. The micropylar region of the inner surface of the envelope had a conical- or bowl-shaped protrusion. In developing eggs, the thickness of the envelope decreased and showed smooth outer and inner surfaces which indicated that it had been stretched tangentially at the time of the perivitelline space formation. The lumen of the micropylar canal was invariably occupied with envelope material. We postulate that the blockage of the micropylar canal is a result of the stretching of the envelope. The closure of the micropyle inhibits sperm and external pathogens from penetrating into the perivitelline space and seems to be involved in both the permanent prevention of polyspermy and the protection of the developing embryo from bacterial infection.     

Cortical reaction and solicitation mechanism in Hemibarbus labeo ovum

There are 1 to 4 rows and five types of cortical alveoli in the cortex of the pallas (Hemibarbus labeo) egg.From the outer to the inner of the cortex,the diameter of the cortical alveoli decreases gradually.We found a new structure named solicitation speckle at the low latitude of the animal pole and near the micropylar apparatus between the ovum envelope and cell membrane in the zygote of fish.The solicitation speckle similar to type I cortical alveoli was very purple in H.E chromosome,and it had no obvious boundary with the ovum envelope and membrane.Moreover,no membrane around the solicitation speckle in TEM was found.In SEM,the solicitation speckle looked flocculent.During cortical reaction,the solicitation speckle played a very important function in arousing cortical reaction.Thirty-five seconds after fertilization,cortical alveoli began to break down near the low latitude of the animal pole.At the same time,the same thing happened near the micropylar apparatus before cortical reaction.Both starting points encountered and healed up at the vestibule of the micropylar apparatus.The cortical reaction that happened near the low latitude of the animal pole was another new pattern.The cortical reaction was divided into four parts that included latent period,developmental period,climactic period and declining period.In the latent period,no cortical alveoli were released.In the developmental period,a few cortical alveoli were released outside the cortex.In the climactic period,several cortical alveoli were inosculated into a big vesicle and released intensely.In the declining period,the type V cortical alveoli and the other remnant cortical alveoli were released.Five minutes after fertilization,cortical alveoli were released entirely in the animal pole.Five minutes after fertilization,all of the remnant cortical alveoli were released.This leads us to Conclude that cortical reaction is induced by type I cortical alveoli,and the solicitation speckle is a volcanic chain reaction under water or the other lower osmotic pressure of fluids.The outer cortical reaction can accelerate the inner cortical reaction.While cortical alveoli releases in batches,the cell plasma membrane is reorganized over and over.No cortical alveoli were found below the micropylar tube where sperm enters the ovum,which suggests that the cortical reaction prevents polyspermy.     

Cortical reaction and solicitation mechanism in Hemibarbus labeo ovum

There are 1 to 4 rows and five types of cortical alveoli in the cortex of the pallas (Hemibarbus labeo) egg. From the outer to the inner of the cortex, the diameter of the cortical alveoli decreases gradually. We found a new structure named solicitation speckle at the low latitude of the animal pole and near the micropylar apparatus between the ovum envelope and cell membrane in the zygote of fish. The solicitation speckle similar to type I cortical alveoli was very purple in H.E. chromosome, and it had no obvious boundary with the ovum envelope and membrane. Moreover, no membrane around the solicitation speckle in TEM was found. In SEM, the solicitation speckle looked flocculent. During cortical reaction, the solicitation speckle played a very important function in arousing cortical reaction. Thirty-five seconds after fertilization, cortical alveoli began to break down near the low latitude of the animal pole. At the same time, the same thing happened near the micropylar apparatus before cortical reaction. Both starting points encountered and healed up at the vestibule of the micropylar apparatus. The cortical reaction that happened near the low latitude of the animal pole was another new pattern. The cortical reaction was divided into four parts that included latent period, developmental period, climactic period and declining period. In the latent period, no cortical alveoli were released. In the developmental period, a few cortical alveoli were released outside the cortex. In the climactic period, several cortical alveoli were inosculated into a big vesicle and released intensely. In the declining period, the type V cortical alveoli and the other remnant cortical alveoli were released. Five minutes after fertilization, cortical alveoli were released entirely in the animal pole. Five minutes after fertilization, all of the remnant cortical alveoli were released. This leads us to conclude that cortical reaction is induced by type I cortical alveoli, and the solicitation speckle is a volcanic chain reaction under water or the other lower osmotic pressure of fluids. The outer cortical reaction can accelerate the inner cortical reaction. While cortical alveoli releases in batches, the cell plasma membrane is reorganized over and over. No cortical alveoli were found below the micropylar tube where sperm enters the ovum, which suggests that the cortical reaction prevents polyspermy. __________ Translated from Acta Hydrobiological Sinica, 2005, 29(5): 479–487 [译自: 水生生物学报, 2005, 29(5): 479–487]     

Morphology of unfertilized mature and fertilized developing marine pelagic eggs in four types of multiple spawning flounders

Starry flounder Platichthys stellatus, spotted halibut Verasper variegates, turbot Scophthalmus maximus, and Japanese flounder Paralichthys olivaceus are four commercially cultivated multiple spawning flounders that spawn pelagic eggs. Through appropriate light and scanning electron microscope processing, the shape and surface structures (such as micropyle, pores, pore density, and paten) of unfertilized mature and fertilized developing eggs of the four species were observed and measured. First, individual or intraspecific comparisons of the surface structures of eggs at different developmental stages were made. Second, interspecific differences among the four species at the same developmental stage of unfertilized mature eggs were statistically computed and analyzed through one-way analysis of variance and hierarchical cluster analysis. Eggs of the same species collected at different stages of development tend to be different in morphology. Smoothing of the convoluted egg envelope surface and closure of the micropyle to serve as a final step of the polyspermy-preventing reaction are common after fertilization. Based on detailed morphology of micropyle of just-mature fertilizable eggs, turbot, starry flounder, and Japanese flounder each have a micropyle with a long canal but no distinct micropylar vestibule, type III of Riehl and Götting (Arch Hydrobiol 74:393–402, 1974). In contrast, spotted halibut has a micropyle with a distinct flat micropylar vestibule and a long canal, type II. Envelope surface microstructures, especially those in the micropyle region, are useful characters for egg identification among the four species. Cluster analysis using selected egg characters indicated the highest similarity between turbot and Japanese flounder and that starry flounder is obviously more similar to turbot and Japanese flounder than to spotted halibut.     

Ultrastructural features of the egg envelope of silver carp, <Emphasis Type="Italic">Hypophthalmichthys molitrix</Emphasis> (Osteichthyes,Cyprinidae)

Synopsis We investigated the ultrastructure of the egg membrane surface (unfertilized egg) of Hypophthalmichthys molitrix using scanning electron microscopy. The eggs of silver carp like most other teleosts are surrounded by a relatively thick egg membrane, and have a type III micropyle at the animal pole. The micropyle is almost circular in shape and the micropyle canal is located in its center. The micropyle region is not flat. Round or oval accessory pores are also observed in the canal. The surface of zona radiata is wavy and uneven with a uniform distribution of almost round pores with lips. Microvilli like structure are found in the pore opening region.