细粒棘球绦虫精子形成的超微结构观察

用透射电镜观察了细粒棘球绦虫精原细胞、精母细胞、精细胞的发育变化和精子的主要形态结构特点，从而揭示了该虫精子的形成过程。结果显示细粒棘球绦虫的精子形成主要是由于精细胞内微管结构的多次排列组合形成的。精细胞和精子中无线粒体和顶体结构。成熟的精子可分为头部和尾部。头部色较淡，顶端有与精子轴丝呈30°角排列的明暗相间的带构成的帽状物包裹。完整精子结构为固有膜包统一条轴丝，轴丝向前伸入头部，向后延伸至尾部。固有膜内线有微管排列，尾部前段一例可有2层做管，多为“2×4＋1，”结构，后段为一层微管紧贴固有腹内缘。抽丝有一个中央微管和9对外周微管组成，中央微管的外围有一个纤维鞘包绕，由纤维鞘发出纤维丝与外周9对微管相连，形成一个车轮状的“9＋1”微管系统结构。     

带绦虫精子发生过程中精子变形的超微结构观察

目的：研究带绦虫在精子发生过程中的精子变形。方法：透射电镜。结果：32个玫瑰花样的次级精母细胞经第2次减数分裂后,产生64个精细原形体（64－spermatid－plasmodium）。精细胞的变形过程复杂,首先见精细胞胞质和核伸长,胞质增多由胞质桥“cytophore”相连;然后是核的进一步伸长,核染色质聚合成线束状,最后脱离胞质桥,形成成熟精子。成熟的精子呈细线状,长约16．2－18．6μm,宽0．35－0．45μm,可分为有核的头部及无核的尾部两部分。头部长约5－6μm,占体长的1／3,有一个较长的核缠绕着轴丝,无线粒体。尾部长约11．2－16．6μm。在尾部的前段及头部的后方,纵断面上见一些线粒体包绕着轴丝,全长约1．6－1．7μm。精子的尾部只含一条结构为“9＋1”的轴丝。精子横断面,质膜下见46条微管（周围微管）。结论：带绦虫精子子的变形是一个非常复杂的过程。     

斯氏狸殖吸虫精子形成的透射电镜观察

用透射电镜观察了斯氏狸殖吸虫精细胞的变化和精子的主要形态结构特征。从而揭示了该虫精子形成的过程。证实了斯氏狸殖吸虫的精细胞和精子有顶体结构。成熟的精子可分为头部和尾部。头部由核质充满,核质可延伸至精子尾部中段的前端。头尾之间为连接段。尾部又由中段和末段组成。尾部的中段起始部的两侧各有一条轴丝。每条轴丝各由9对外周微管和2个中央微管组成,在每2条中央微管的外围,均由一个纤维鞘包绕,其间形成一个车轮样的9 2微管系统结构,其腹侧排列着线粒体。尾部的末段,主要为2条紧靠的轴丝。     

贾第虫滋养体的扫描电镜观察

分离、浓缩贾第虫包囊,人工感染家兔获得滋养体。扫描电镜观察滋养体呈倒置梨形,12～16.5×6.5～7.7μm。前端钝圆,后端尾部变细。背面隆起,表面呈桔皮样。前端腹面有一个不对称的螺旋形腹吸盘。虫体周缘具有突出的伪足样周翼,其背腹面均光滑,该翼与腹吸盘侧嵴和虫体背面之间分别形成边缘沟。滋养体有4对鞭毛,均由背侧边缘沟伸出体外。     

刚地弓形虫速殖子超微结构观察

刚地弓形虫(Toxoplasma gondii)的速殖子在人体急性感染期对致病有重要意义。国内对弓形虫的超微结构报道较少。为适应当前对弓形虫研究的需要,我们对速殖子超微结构进行了深入观察。 弓形虫速殖子呈半月形或香蕉形,前端较尖,后端钝圆,一边较扁平,一边较弯曲,大小约5～6×1.8～2.5μm,虫体外有细胞膜包绕。虫体前端有极环和类锥体,极环由内膜的前端增厚形成,厚约58.8～     

南京所见一种裂体吸虫与日本血吸虫形态及生活史比较

用自然环境中钉螺逸出的尾蚴感染小鼠和兔,获得了一种比日本血吸虫小的裂体吸虫。雄虫大小(7.14±0.64)mm×(0.58±0.03)mm,口吸盘较大0.54mm×0.59mm;腹吸盘更大0.65mm×0.68mm,超过虫体宽度,且圆边构造不明显;睾丸4～8个,多为8个,重叠排成两行;背部有密集杵状小棘。雌虫(7.19±1.12)mm×(0.37±0.02)mm,子宫内有虫卵20～80个。雌雄合抱寄生在肠系膜下静脉、肠系膜上静脉、肝内门脉血管和膀胱静脉丛的小静脉和末梢静脉中。虫卵有钩状或环状微侧刺。终宿主小鼠的虫卵开放前期32.6d±1.2d,比日本血吸虫短1.4d。中间宿主钉螺的开放前期比日本血吸虫长1周以上。与钉螺的相容性差,钉螺的感染率3.7%～6.6%,显著低于日本血吸虫的感染率31.7%～46.6%(P值均＜0.01)。这些特性表明该裂体吸虫与日本血吸虫不同。     

克拉玛依地区的利什曼病——Ⅱ.新疆克拉玛依大沙鼠体内利什曼原虫无鞭毛体的亚显微结构

对新疆克拉玛依大沙鼠体内利什曼原虫无鞭毛体进行了亚显微结构的观察,结果表明虫体较一般致病的利什曼原虫为大。其长为4.21±0.95μm(2.41～5.56μm)宽为1.58±0.34μm(1.10～2.28μm,周长为9.98±2.01μm(6.41～13.21μm),虫体的膜下微管数在有细胞核的切面上为92±13(71～118),而在有鞭毛的切面上则为71±10(59～94),说明虫体不同部位的膜下微管数是不同的。膜下微管的走向并非全呈直线状。微管的直径为25nm,间距为20～30nm;微管间有与内质网相联的弯曲小管,开口于虫体的体表,并有电子致密物联结微管。质膜厚度为8nm。在胞质内有线粒体、内质网、高尔基体等细胞器。此外,还见到菊形管状和包涵体样结构,但其意义不明。     

贾第虫包囊的电镜观察

从带虫者的粪便中取得贾第虫包囊,做成标本进行透射电镜观察。包囊呈椭圆形,大小8.5～12.5×6～7μm,囊壁厚0.16～0.29μm。囊壁与虫体之间空隙内可见横、纵切面的鞭毛结构。虫体外界膜内面排列一圈由单层单位膜围绕的空泡,内含大小不等的颗粒。虫体胞质内有小颗粒的核糖体和染色较深的大颗粒,     

计算机图象分析系统测量阴道毛滴虫:形态学数据和参数的建立和分析

目的　建立并分析阴道毛滴虫的形态学数据和参数。　方法　用计算机图象分析系统得到阴道毛滴虫及核的长、宽、周长、长宽比、等效圆直径、圆度、面积、前鞭毛与后鞭毛、轴柱长度。计算滋养体和核的体积。　结果　滋养体的大小为 15 .0 11μm(9.2 2 2～ 2 1.796μm)× 12 .0 5 8μm(5 .86 8～ 17.6 0 5μm)。前鞭毛、后鞭毛和轴柱的长度分别 18.2 7μm、17.4 1μm、2 1.94μm。相关分析显示滋养体与核的面积 (r=0 .5 4 ,P<0 .0 1)、滋养体与核体积 (r=0 .4 7,P<0 .0 1)相关性有显著性意义 ,滋养体面积和核圆度呈负相关 (r=- 0 .2 9,P<0 .0 1) ,滋养体圆度和核圆度之间无相关性。　结论　参数间的相关系数显示 ,随着滋养体增大 ,虫体的形态变圆 ,而核的形态变化不大。阴道毛滴虫形态学数据和参数的建立为量化及评价虫体的形态奠定了基础。     

一氧化氮对日本血吸虫童虫细胞毒作用的研究

目的 研究一氧化氮(NO)对日本血吸虫童虫的杀伤作用。 方法 用LPS或LPS+IFN-γ诱导离体的小鼠腹腔巨噬细胞,使其产生NO;加入机械断尾的日本血吸虫童虫,测定48 h内童虫的死亡率。为进一步证实NO对童虫的杀伤作用,用诱导型一氧化氮合酶(iNOS)的抑制剂L-NNA(Nω-nitro-L-arginine)抑制NO的产生,与未加抑制剂组比较,观察童虫死亡率的变化。 结果 LPS或LPS+IFN-γ均能有效诱导巨噬细胞产生NO,2.0×10~5细胞产生的NO浓度分别为(109.96±3.70)μmol/L和(113.50±7.38)μmol/L,其相应的杀虫率分别达91.07％±2.92％和96.86％±2.36％。加入2 mmol/L的L-NNA后,巨噬细胞的NO产量明显降低,其杀虫率也相应减低。 结论 巨噬细胞诱生的NO对日本血吸虫童虫具杀伤作用。     

Ultrastructural observation of spermatozoa and fertilization in Schistosoma japonicum

The ultrastructure of the sperm and the process of fertilization are described in Schistosoma japonicum. The sperm of S. japonicum has an elongated head and a single tail. The head measures 6.2 x 1.4 microm in average size. No acrosome is present. A mass of mitochondria locates in front of the nucleus. A layer of about 100-120 peripheral microtubules is parallel with the long axis of the head under plasma membrane. The nucleus is dense with some electron-lucent patches. The tail is a single flagellum with unique axoneme, which originates from a centriole. The structure of axoneme includes two types: 9 x 2 + in the main part of the flagellum, and 9 x 2 + 0 near the end of the flagellum. The sperm ultrastructure of S. japonicum is similar to that of other schistosomes, apart from the fact that two types of configuration coexisted in the same axoneme, and there is no striated root found in S. japonicum. The sperm differs distinctly from other Digenea. The aberrant ultrastructure of S. japonicum reflects that its evolution is far away from other genera in Digenea. Fertilization occurs at the posterior part of oviduct, in which region the oviduct wall lacks lamellae. Some cortical granules (CG) fuse with plasma membrane, and discharge their content on the surface of the fertilized ovum. The other CGs break down or degenerate in the cytoplasm. By the secondary mature division, the secondary oocyte finally divides to form a female pronucleus. During this period a male pronucleus also forms. The female and male pronucleus approach each other, come into contact in the central region and finally fuse to form a zygote. The function of CGs is discussed.     

Protein kinase C and Mammalian spermatozoa acrosome reaction.

The presence of protein kinase C (PKC) in mammalian sperm was demonstrated by enzymatic activity assay and immunohistochemistry at the light and electron microscopy levels. The sperm head PKC is localized in the acrosome, equatorial segment, and postacrosomal region. In the flagellum, PKC is associated with the segmented column of the neck and is distributed along the mid, principal, and end pieces. Immunoreactive sites are observed in patches along the axoneme and outer dense fibers and are evenly distributed between these regions. Functional studies suggest the involvement of PKC in flagellar motility and acrosome reaction. The cross-talk between the signaling cascades that operate during sperm activation is discussed. (Trends Endocrinol Metab 1997;8:337-341). (c) 1997, Elsevier Science Inc.     

Calmodulin localization in mammalian spermatozoa.

The location of calmodulin in rabbit and guinea pig spermatozoa was determined by indirect immunofluorescence techniques. Spermatozoa that had not undergone the acrosome reaction exhibited four distinct regions of calmodulin-specific immunofluorescence: around the acrosome, in a band across the lower third of the head, and in two localized areas at the base and tip of the flagellum. In contrast, after the acrosome reaction, although other features of calmodulin distribution remained the same, the fluorescence associated with the anterior half of the head was notably absent. Instead, fluorescence was associated with the membranes that had separated from the sperm head. These findings suggest a potential role for calmodulin in the Ca2+-dependent control of sperm activation, in sperm-egg fusion, and in microtubule disassembly processes in the flagellum.     

Structure of Trypanosoma brucei flagellum accounts for its bihelical motion

Trypanosoma brucei is a parasitic protozoan that causes African sleeping sickness. It contains a flagellum required for locomotion and viability. In addition to a microtubular axoneme, the flagellum contains a crystalline paraflagellar rod (PFR) and connecting proteins. We show here, by cryoelectron tomography, the structure of the flagellum in three bending states. The PFR lattice in straight flagella repeats every 56 nm along the length of the axoneme, matching the spacing of the connecting proteins. During flagellar bending, the PFR crystallographic unit cell lengths remain constant while the interaxial angles vary, similar to a jackscrew. The axoneme drives the expansion and compression of the PFR lattice. We propose that the PFR modifies the in-plane axoneme motion to produce the characteristic trypanosome bihelical motility as captured by high-speed light microscope videography.     

Bypassing natural sperm selection during fertilization: the azh mutant offspring experience and the alternative of spermiogenesis in vitro

Molecular aspects of spermiogenesis can be studied using mouse mutants and spermatids developed in vitro. The azh/azh mutant is an attractive model system because structural abnormalities in the sperm head and the ectopic position of the manchette are associated with tail bending and looping. Spermatids, developing an axoneme in vitro and capable of cell motility, offer the possibility of the dynamic analysis of tail development. Offspring generated by intracytoplasmic injection of azh/azh sperm heads into normal mouse oocytes complement the mouse mutant approach. A central question of sperm tail development is the role of the manchette, a transient microtubular structure assembled soon after the organization of the axoneme. The fractionation of intact manchettes by gradient centrifugation has enabled a biochemical analysis of constitutive tubulin isotypes and transiently associated proteins. For example, keratins Sak57, Odf1, and Odf2 are initially stored in the manchette before being sorted to the outer dense fibers and fibrous sheath of the developing spermatid tail. Additional proteins associated with the manchette include two proteases, the 26S proteasome and N-arginine convertase (both sorted to the developing spermatid tail), a spermatid perinuclear RNA binding protein, Spag4, an Odf1-binding protein, and type 4 cAMP-specific phosphodiesterase D. Keratin 9 and delta-tubulin are two proteins found in the perinuclear ring of the manchette, the insertion site of the microtubular mantle. Available data indicate that the manchette is a highly dynamic structure providing microtubular tracks to structural proteins participating in the sperm tail development.     

A flagellar K(+)-dependent Na(+)/Ca(2+) exchanger keeps Ca(2+) low in sea urchin spermatozoa

The metabolism, flagellar beating, and acrosome reaction of spermatozoa are regulated by ion flux across the plasma membrane. As is true of most cells, swimming sperm maintain intracellular Ca(2+) concentrations at submicromolar levels. Here we describe a K(+)-dependent Na(+)/Ca(2+) exchanger (suNCKX) from sea urchin sperm. The suNCKX is phylogenetically related to other NCKXs, which use high relative intracellular K(+), and high relative extracellular Na(+), to couple the efflux of 1 Ca(2+) and 1 K(+) to the influx of 4 Na(+). The 652-aa suNCKX shares structural topology with other NCKX proteins, and has two protein kinase A sites and a His-rich region in its cytoplasmic loop. The suNCKX is encoded by a single gene, which is highly expressed in testes. The suNCKX activity of whole sperm shows Na(+) and K(+) dependence, and like other NCKXs can run in reverse exchange mode. An inhibitor blocks the suNCKX activity and sperm motility. suNCKX localizes to the plasma membrane over the sperm flagellum. The suNCKX may play a major role in keeping Ca(2+) low in swimming sperm.     

Lipid domains in the ram sperm plasma membrane demonstrated by differential scanning calorimetry.

Mammalian sperm plasma membranes, in contrast to those of mammalian somatic cells, exhibit a significant fraction of lipid that does not diffuse laterally in the plane of the membrane. This nondiffusing fraction results from lipid-lipid interactions. Similar nondiffusing fractions are found in mixed-lipid model systems that contain coexistent gel and fluid domains. These results suggest that the sperm plasma membrane may also exhibit lateral phase segregations of lipids and may contain significant amounts of gel-phase lipid. In this paper we use differential scanning calorimetry to show that, in contrast to the plasma membranes of mammalian somatic cells, the plasma membrane from the anterior region of the head of ram sperm exhibits at least two major endothermic transitions, one centered at approximately 26 degrees C and one centered at approximately 60 degrees C. The heats of these transitions are consistent with gel-to-fluid transitions in model membranes. These transitions are observed both in plasma membrane vesicles and in rehydrated lipid extracts made from these vesicles. These results demonstrate that at physiological temperatures the lipids of the ram sperm plasma membrane are segregated into coexistent fluid and gel domains. Since sperm encounter a wide range of temperatures during their development, these phase transitions may be important in establishing dynamic domains of lipid requisite for epididymal storage and fertilization.     

Molecular diffusion in sperm plasma membranes during epididymal maturation

Fluorescence recovery after photobleaching (FRAP) analysis has been used to measure lipid diffusion in different regions of the sperm plasma membrane. Our goal has been to understand how some membrane components are confined to specific surface domains, whilst others are freely diffusing and in some cases are able to migrate against large concentration gradients. Results with a variety of fluorescent lipid reporter probes (ODAF, NBD-PC, NBD-cholesterol) show that diffusion coefficients (D) are generally three to four times higher on the sperm acrosome than on the principal piece of the tail and increase significantly during epididymal maturation (ram, mouse, goat, dog and monkey sperm). Cholesterol diffusion is approximately 10 times faster on the sperm head than the tail and has a heterogenous distribution when detected with filipin. Lipid diffusion is very temperature sensitive but remarkably insensitive to changes in external pH and osmotic pressure. There was no evidence that the posterior ring or annulus functioned as diffusion barriers to lipids. On this basis it was possible to construct models of increasing complexity to describe the behaviour of a lipid molecule on the sperm surface, beginning with simple linear diffusion progressing to random diffusion and eventually to constrained diffusion.