中国石龙子成熟精子的超微结构

利用透射电镜观察中国石龙子附睾成熟精子的超微结构。顶体囊前部扁平、由皮质和髓质组成 ,穿孔器中度倾斜、顶端尖 ,穿孔器基板塞子状 ,细胞核长形 ,核内小管缺 ,核前电子透亮区小 ,核肩圆 ,核陷窝锥形。颈段具片层结构 ,近端中心粒和远端中心粒的长轴呈直角 ,9束外周致密纤维与远端中心粒相应的 9束三联微管相联 ,向后与轴丝相应的 9束双联微管相联 ,中央纤维与 2个中央单微管相联。中段短 ,多层膜结构缺 ,含有线状嵴的柱状线粒体 ,不规则卵状致密体组成不连续的环状结构 ,纤维鞘伸入中段 ,具终环。线粒体与环状结构的模式为 :rs1 /mi1 ,rs2 /mi2 ,rs3/mi3,rs4 /mi4。主段前面部分具薄的细胞质颗粒区。纤维 3和 8至主段前端消失。轴丝呈“9 2”型。中国石龙子精子超微结构具有塞子状的穿孔器基板、致密体形成不连续的环状结构和纤维鞘始于ms2等特征与巨石龙子群和蜓蜥 -胎生群不同。没有发现石龙子科精子的独征     

北草蜥精子的超微结构--兼评不同类群蜥蜴精子形态的差异

应用透射电镜对北草蜥精子的超微结构研究结果表明,北草蜥精子头部顶体囊始终呈圆形,由皮质和髓质组成;顶体囊单侧脊的皮质与髓质问具电子透亮区;穿孔器1个,无穿孔器基板;具顶体下腔;细胞核长形,核内小管缺,核前电子透亮区缺,核肩圆。尾部颈段具片层结构。中段短,多层膜结构缺;纵切面上具2层线粒体;横切面上每圈线粒体6个;2组致密体,具连续的环状结构;线粒体与环状结构的排列模式：rs1／mi1、rs2／mi2;纤维鞘伸人中段,具终环。主段前面部分具薄的细胞质颗粒区;纤维3和8至主段前端消失;轴丝呈“9＋2”型。蜥蜴科内不同种类的线粒体数目不同,但都具有2组致密体。不同类群蜥蜴的顶体囊、顶体下腔、核前电子透亮区、穿孔器基板、核肩,以及线粒体与致密体的数目和排列方式等精子超微结构特征都为研究蜥蜴的系统发生提供了辅助信息。     

家鸽睾丸精子超微结构的观察

家鸽(Columbadomestica)精子分为头部、颈部及尾部。尾部又区分为中段、主段及末段。头部呈圆柱形,主要被精细胞核占据,核的前面包绕顶体,后端连接颈部。颈部有两个中心粒,与头部相邻接的是与精子纵轴垂直的近侧中心粒,远侧中心粒形成基底体向后发出尾部的轴丝。轴丝的结构为9+2型。中段在轴丝之外有线粒体鞘包绕,最外面为质膜。主段和末段无线粒体鞘,轴丝之外直接被以质膜。     

文昌鱼精子的超显微结构

文昌鱼(Branchiostoma belcheri tsingtaoensis)的成熟精子由一个锥形的顶体,头部,颈(被核包裹)和尾部组成。尾可分为中段,主段和末段。微管对复合体为9+2。 文昌鱼精子的超显微结构与前人报道的线粒体由4—6个组成的不同。它由一个大的线粒体围绕尾主轴中段,而且精子属于对称性类型,可以见到核内管,中心粒和致密纤维,终环结构与隐窝位于尾中段与主段之间。本文并对文昌鱼在系统发生中的重要位置和意义作了讨论。     

大鲵精子结构研究

为了解大鲵精子超微结构,应用扫描电镜和透射电镜开展了大鲵精子形态结构研究。结果显示:大鲵精子由头部、颈部和尾部3部分组成。精子总长216.36μm±9.93μm(n=30),头部长65.80μm±3.70μm(n=30),颈部较短,多不明显,尾部长153.52μm±3.22μm(n=30)。头部由顶体、穿孔器和细胞核组成;颈部包括核窝、近端中心粒及远端中心粒、线粒体、轴丝和轴纤维;尾部无明显分段,由轴丝、轴纤维、轴丝旁纤维和波动膜组成。大鲵精子内线粒体较少,可能与精子运动缓慢、精子活力维持时间短有关;成熟过程中精子细胞头部包围的胞质分泌物中含有一定数量的线粒体。     

耳鲍精子的超微结构

本文利用透射电子显微镜对耳鲍(Haliotis asinina Linnaeus)精子的形态及超微结构进行了研究.研究结果表明:耳鲍的精子由头部、中段和尾部三部分组成,全长 41.6 μm.精子头部长 1.8 μm,头部由顶体、顶体下腔和细胞核组成,顶体电子密度比较均匀,呈圆锥形,长 0.6 μm,基部宽度为 0.65 μm,占头部长的 1/3;顶体下腔长 0.03 μm,宽为 0.65 μm,腔中含有中等电子密度物质;细胞核圆棒状,长 1.17 μm,核中部的宽度为 1.0 μm.精子中段较短,长 0.51 μm,宽 1.2 μm,主要由 5 个线粒体包围一对中心粒构成.尾部是一根鞭毛,从前到后逐渐变细,鞭毛是由细胞质膜包被的轴丝组成,轴丝为典型的"9 2"微管结构,即轴丝是由两个中心微管及均匀分布在中心微管周围的 9 对双联体微管组成.因此,耳鲍与其它鲍类精子的基本结构相似,形态结构的主要差异表现在三个方面:一是耳鲍精子的头部似圆锥形,长 1.8 μm,是目前已研究的鲍类中头部最短的种类;二是耳鲍精子顶体长比其基部宽要小,顶体电子密度比较均匀,顶体与核的电子密度差异不明显;三是耳鲍精子中段线粒体的数量为 5 个,没有发现 6 个线粒体现象的存在[动物学报 53(3):552-556,2007].     

毛蚶与青蚶精子超微结构及其所反映的蚶科进化关系

应用透射电镜技术,比较研究了毛蚶与青蚶精子的超微结构。毛蚶精子顶体为圆锥形,约为核长的1／2;精核无核前窝,具核后窝;中段横切面常见5个(偶见4个)线粒体环绕于中心粒周围;精子末段由轴丝及包绕轴丝的质膜组成,轴丝为典型的“9 2”结构。青蚶精子顶体轴向纵切面呈伞状,覆盖于细胞核前端,约为核长的1／3;精核具核前窝和核后窝;中段横切面常见有5个(偶见6个)线粒体环绕于中心粒周围;末段结构同毛蚶。顶体的形态、核前窝和核后窝的有无、中段线粒体的数量等是探索蚶科动物种间进化关系的线索。     

两种石龙子精子超微结构的比较

利用透射电镜研究多线南蜥和印度蜓蜥附睾精子的超微结构。两种卵胎生石龙子的精子具有一些有鳞类精子的共同特征,即具有顶体囊、顶体下锥、单个核前穿孔器和核喙,无核内管,纤维鞘伸入中段,与双联微管3和8相邻的外周致密纤维具双份纤维结构。多线南蜥和印度蜓蜥精子超微结构的种间差异主要表现在:多线南蜥精子核前方的顶体下锥电子密度较小,顶体囊具单侧嵴,横切面上可见非连续的致密体环或11个线粒体;印度蜓蜥无单侧嵴,横切面上可见连续的致密体环或12个线粒体。迄今未发现石龙子科精子的独征,但该科不同类群的顶体囊、顶体下腔、核前方的顶体下锥电子致密程度、核肩、纵切面线粒体与致密体的排列方式、横切面致密体环形状和线粒体等精子超微结构特征有一定程度的差异。这些差异可为研究石龙子科系统发生提供辅助信息。     

可口革囊星虫的精子发生及精子结构

为了探究可口革囊星虫(Phascolosoma esculenta)精子发生过程及结构上的特殊性,用显微及亚显微技术研究了可口革囊星虫的精子发生和精子结构。可口革囊星虫的精巢位于收吻肌基部,为一曲折的带状组织。成熟精巢内可观察到精原细胞、精母细胞以及精细胞等各阶段的生精细胞。在精子形成早期,很多精细胞脱离精巢,以精细胞团的形式掉落到体腔中。精细胞团内的精细胞同步发育为精子后,脱离精子团进入肾管。成熟精子由头部和尾部组成。头部由钟形顶体与鼓形细胞核构成。顶体后段下包于精核的前端。顶体分内、中、外三层,外层有横隔;顶体下腔内有颗粒状物质不均匀分布,中央有一束丝状纤维组成的顶体棒。核物质电子密度高,核内含空泡。无核前窝,具浅的核后窝。尾部分中段和末段,中段由6个(偶见5个或7个)线粒体围绕近、远端中心粒构成;末段细长鞭状,由轴丝及包绕轴丝的质膜组成,轴丝为典型的"9 2"结构。分析认为:可口革囊星虫精子发生过程以及超微结构上存在特殊的结构与机制:①精细胞团保证了精子形成的同步性;②顶体后段下包于精核的前端使精子头部小而灵巧,利于快速运动;③顶体的横隔使精子顶体的牢固性增强,确保受精时顶体反应的正常进行;④中段较多的线粒体使精子具有更强的环境适应性,有利于有效的受精。     

黄姑鱼（ Nibea albiflora） 与大黄鱼（ Pseudosciaena crocea） 精子超微结构的观察与比较

应用扫描电镜（SEM）与透射电镜（TEM）观察了黄姑鱼和大黄鱼精子的超微结构。结果显示,黄姑鱼和大黄鱼精子无论在形态、大小还是超微结构上都十分相似。黄姑鱼和大黄鱼精子均由头部、中段和尾部（鞭毛）3部分组成。精子头部形状近似椭圆形,无顶体,细胞核呈肾形。中心粒复合体位于细胞核背侧,近、远端中心粒相互垂直,远端中心粒分化成基体并形成轴丝。中段的袖套呈筒状,4～5个圆形的线粒体围绕轴丝呈环形排列。精子尾部为单鞭毛,轴丝为典型“9＋2”结构,鞭毛表面质膜形成不规则侧鳍。     

Ultrastructure of the spermatozoon of the American Alligator,Alligator mississippiensis (Reptilia: Alligatoridae)

This study details the ultrastructure of the spermatozoa of the American Alligator, Alligator mississippiensis. American Alligator spermatozoa are filiform and slightly curved. The acrosome is tapered at its anterior end and surrounded by the acrosome vesicle and an underlying subacrosomal cone, which rests just cephalic to the nuclear rostrum. One endonuclear canal extends from the subacrosomal cone through the rostral nucleus and deep into the nuclear body. The neck region separates the nucleus and midpiece and houses the proximal centriole and pericentriolar material. The distal centriole extends through the midpiece and has 9 × 3 sets of peripheral microtubules with a central doublet pair within the axoneme that is surrounded by a dense sheath. The midpiece is composed of seven to nine rings of mitochondria, which have combinations of concentrically and septate cristae. The principal piece has a dense fibrous sheath that surrounds an axoneme with a 9 + 2 microtubule arrangement. The sheath becomes significantly reduced in size caudally within the principal piece and is completely missing from the endpiece. Dense peripheral fibers, especially those associated with microtubule doublets 3 and 8, penetrate into the anterior portion of the principal piece axoneme. The data reported here hypothesize that sperm morphology is highly conserved in Crocodylia; however, specific morphological differences can exist between species. J. Morphol. 2011. © 2011 Wiley‐Liss, Inc.     

The ultrastructure of the spermatozoa of Epipedobates flavopictus (Amphibia,Anura, Dendrobatidae), with comments on its evolutionary significance

We describe, for the first time, the spermatozoon ultrastructure of a dendrobatid frog, Epipedobates flavopictus. Mature spermatozoa of E. flavopictus are filiform, with a moderately curved head and a proportionally short tail. The acrosomal vesicle is a conical structure that covers the nucleus for a considerable distance. A homogeneous subacrosomal cone lies between the acrosome vesicle and the nucleus. The nucleus contains a nuclear space at its anterior end, and electron-lucent spaces and inclusions. No perforatorium is present. In the midpiece, the proximal centriole is housed inside a deep nuclear fossa. Mitochondria are scattered around the posterior end of the nucleus and inside the undulating membrane in the anterior portion of the tail. In transverse section the tail is formed by an U-shaped axial fiber connected to the axoneme through an axial sheath, which supports the undulating membrane. The juxta-axonemal fiber is absent. The spermatozoon of E. flavopictus has several characteristics not observed before in any anurans, such as a curved axial fiber, absence of a juxta-axonemal fiber, and presence of mitochondria in the typical undulating membrane. Our results endorse the view that, in anurans, the conical perforatorium and subacrosomal cone are homologous and that Dendrobatidae should be grouped within Bufonoidea rather than Ranoidea.     

Ultrastructure of the spermatid of Caprimulgus europaeus Linnaeus 1758, the European nightjar (Aves; Caprimulgidae), with phylogenetic implications

The sperm of Caprimulgus europaeus is typical of other nonpasserines in many respects. Features shared with Paleognathae and Galloanserae are the conical acrosome, shorter than the nucleus; the presence of a perforatorium and endonuclear canal; the presence of a proximal as well as distal centriole; the elongate midpiece with mitochondria grouped around a central axis (here maximally six mitochondria in approximately 10 tiers); and the presence of a fibrous or amorphous sheath around the principal piece of the axoneme. A major (apomorphic) difference from paleognaths and galloanserans is the short distal centriole, the midpiece being penetrated for most of its length by the axoneme and for only a very short proximal portion by the centriole. Nonpasserines differ from paleognaths in that the latter have a transversely ribbed fibrous sheath, whereas in nonpasserines it is amorphous, as in Caprimulgus, or absent. The absence of an annulus is an apomorphic feature of Caprimulgus, apodiform, psittaciform, gruiform, and passerine sperm, homoplastic in at least some of these. In contrast to passerines, in Caprimulgus the cytoplasmic microtubules in the spermatid are restricted to a transient longitudinal manchette. The structure of the spermatid and spermatozoon is consistent with placement of the Caprimulgidae near the Psittacidae, but is less supportive of close proximity to the Apodidae, from DNA-DNA hybridization and some other analyses.     

Ultrastructure of spermiogenesis in the American alligator,Alligator mississippiensis (Reptilia,Crocodylia, Alligatoridae)

Testicular samples were collected to describe the ultrastructure of spermiogenisis in Alligator mississipiensis (American Alligator). Spermiogenesis commences with an acrosome vesicle forming from Golgi transport vesicles. An acrosome granule forms during vesicle contact with the nucleus, and remains posterior until mid to late elongation when it diffuses uniformly throughout the acrosomal lumen. The nucleus has uniform diffuse chromatin with small indices of heterochromatin, and the condensation of DNA is granular. The subacrosome space develops early, enlarges during elongation, and accumulates a thick layer of dark staining granules. Once the acrosome has completed its development, the nucleus of the early elongating spermatid becomes associated with the cell membrane flattening the acrosome vesicle on the apical surface of the nucleus, which aids in the migration of the acrosomal shoulders laterally. One endonuclear canal is present where the perforatorium resides. A prominent longitudinal manchette is associated with the nuclei of late elongating spermatids, and less numerous circular microtubules are observed close to the acrosome complex. The microtubule doublets of the midpiece axoneme are surrounded by a layer of dense staining granular material. The mitochondria of the midpiece abut the proximal centriole resulting in a very short neck region, and possess tubular cristae internally and concentric layers of cristae superficially. A fibrous sheath surrounds only the axoneme of the principal piece. Characters not previously described during spermiogenesis in any other amniote are observed and include (1) an endoplasmic reticulum cap during early acrosome development, (2) a concentric ring of endoplasmic reticulum around the nucleus of early to middle elongating spermatids, (3) a band of endoplasmic reticulum around the acrosome complex of late developing elongate spermatids, and (4) midpiece mitochondria that have both tubular and concentric layers of cristae. J. Morphol., 2010. © 2010 Wiley‐Liss, Inc.     

The Ultrastructure of the Spermatozoa of Squamata—I. Scincidae,Gekkonidae and Pygopodidae (Reptilia)

Abstract Squamate autapomorphies seen in sperm of the Scincidae (e.g. Ctenotus robustus, Carlia pectoralis, Cryptoblepharus virgatus, and Lampropholis delicata) are penetration of the fibrous sheath of the axoneme into the midpiece, and the paracrystalline subacrosomal cone. Sphenomorphus group spermatozoa (e.g. Ctenotus) and the Egernia group (Tiliqua) differ from the more derived Eugongylus group (C. virgatus, L. delicata and C. pectoralis) in that the acrosome is elongate and apically depressed; the perforatorium is strongly oblique; the midpiece is relatively short, with four dense ring structures in longitudinal succession; mitochondria are columnar; and enlarged peripheral fibres 3 and 8 do not show the gross anterior enlargement seen in Carlia and Lampropholis. Heteronotia binoei (Gekkonidae) sperm have no epinuclear electron-lucent region; nuclear shoulders are smooth, as in sphenomorph but not Eugongylus group skinks; mitochondria are columnar; unlike skinks, the median surfaces of the mitochondria are indented by triangular, sometimes longitudinally, interconnected dense bodies. In Lialis burtonis (Pygopodidae) sperm, the perforatorium extends virtually to the tip of the fore-shortened apically domed acrosome; nuclear shoulders are absent; the mitochondria alternate singly or in groups with one or more dense bodies which also form an interrupted collar around the distal centriole. Spermatozoal ultrastructure suggests that a common ancestry of snakes and pygopods deserves consideration.     

Ultrastructure of the spermatozoon of Apus apus (Linnaeus 1758), the common swift (Aves; Apodiformes; Apodidae), with phylogenetic implications

The spermatozoon of Apus apus is typical of non‐passerines in many respects. Features shared with palaeognaths and the Galloanserae are the conical acrosome, shorter than the nucleus; the presence of a proximal as well as distal centriole; the elongate midpiece with mitochondria grouped around an elongate distal centriole; and the presence of a fibrous or amorphous sheath around the principal piece of the axoneme. The perforatorium and endonuclear canal are lost in A. apus as in some other non‐passerines. All non‐passerines differ from palaeognaths in that the latter have a transversely ribbed fibrous sheath whereas in non‐passerines it is amorphous, as in Apus, or absent. The absence of an annulus is an apomorphic but homoplastic feature of swift, psittaciform, gruiform and passerine spermatozoa. The long distal centriole, penetrating the entire midpiece, is a remarkably plesiomorphic feature of the swift spermatozoa, known elsewhere only in palaeognaths. The long centriole of Apus, if not a reversal, would be inconsistent with the former placement of the Apodiformes above the Psittaciformes from DNA–DNA hybridization. In contrast to passerines, in A. apus the microtubules in the spermatid are restricted to a transient single row encircling the cell. The form of the spermatozoon fully justifies the exclusion of swifts from the passerine family Hirundinidae.