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 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.     

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     

蓝尾石龙子精子的超微结构

蓝尾石龙子(Eumeces elegans)附睾以2．5％戊二醛和1％锇酸双重固定,按常规制作超薄切片,用H-600透射电镜研究观察精子的超微结构。精子由头部和尾组成,头部由顶体复合体和核组成,尾由颈段、中段、主段和末段组成。头部的顶体囊前部扁平,分为皮质和髓质,顶体下锥由类结晶状的顶体下物质组成,穿孔器顶端尖,、穿孔器基板塞子状,细胞核延长,核内小管缺,核伸展部前端具一电子透明区,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,含有线状嵴的柱状线粒体,由连续的规则小卵状或小梯形致密体组成线粒体间的环状结构,纤维鞘伸入中段,终环紧贴于细胞膜的内表面。线粒体与环状结构的模式为：rs1／mi1,rs2／mi2,rs3／mi3,rs4／mi4,横切面上每圈线粒体数目为10个。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。轴丝复合体呈“9 2”型。蓝尾石龙子精子超微结构与已描述的石龙子科种类比较发现,与蜓蜥群和胎生群的石龙子相似;但没有发现石龙子科精子的独征。     

Ultrastructure of the mature spermatozoa of caecilians (Amphibia: Gymnophiona)

The spermatozoa of Gymnophiona show the following autapomorphies: 1) penetration of the distal centriole by the axial fiber; 2) presence of an acrosomal baseplate; 3) presence of an acrosome seat (flattened apical end of nucleus); and 4) absence of juxta-axonemal fibers. The wide separation of the plasma membrane bounding the undulating membrane is here also considered to be apomorphic. Three plesiomorphic spermatozoal characters are recognized that are not seen in other Amphibia but occur in basal amniotes: 1) presence of mitochondria with a delicate array of concentric cristae (concentric cristae of salamander spermatozoa differ in lacking the delicate array); 2) presence of peripheral dense fibers associated with the triplets of the distal centriole; and 3) presence of a simple annulus (a highly modified, elongate annulus is present in salamander sperm). The presence of an endonuclear canal containing a perforatorium is a plesiomorphic feature of caecilian spermatozoa that is shared with urodeles, some basal anurans, sarcopterygian fish, and some amniotes. Spermatozoal synapomorphies are identified for 1) the Uraeotyphlidae and Ichthyophiidae, and 2) the Caeciliidae and Typhlonectidae, suggesting that the members of each pair of families are more closely related to each other than to other caecilians. Although caecilian spermatozoa exhibit the clear amphibian synapomorphy of the unilateral location of the undulating membrane and its axial fiber, they have no apomorphic characters that suggest a closer relationship to either the Urodela or Anura.     

Descriptions of the mature spermatozoa of the lizards Crotaphytus bicinctores, Gambelia wislizenii (Crotaphytidae), and Anolis carolinensis (Polychrotidae) (Reptilia, Squamata, Iguania)

The spermatozoa of Crotaphytus bicinctores and Gambelia wislizenii (Crotaphytidae), and Anolis carolinensis (Polychrotidae) exhibit the squamate autapomorphies of a single perforatorium extending anteriorly from the apical tip of the paracrystalline subacrosomal cone, the presence of an epinuclear electron-lucent region, and extension of the fibrous sheath into the midpiece. Crotaphytid sperm differ from those of polychrotids in several respects, including: the structure of the perforatorium, the size of the epinuclear electron-lucent region, aspects of the acrosome complex, the arrangement and structure of intermitochondrial dense bodies, and in the distance the fibrous sheath extends into the midpiece. The sperm of C. bicinctores, G. wislizenii, and A. carolinensis are most similar to those of the agamids and phrynosomatids examined to date. No spermatozoal autapomorphies for Crotaphytidae or Polychrotidae were found. The condition of having the intermitochondrial dense bodies arranged in regular incomplete rings is tentatively defined as a synapomorphy of Iguania (although modified in Chamaeleonidae). Spermatozoal ultrastructure offers no characters that justify the separation of Iguanidae (sensu lato) into several separate families.     

Ultrastructure des spermatozoides des males haploides et diploides de Diadromus pulchellus wesmeal (Hymenoptera : Ichneumonidae)

The mature spermatozoa were described in the haploïd and diploïd males of Diadromus pulchellus Wesmeal (Hymenoptera : Ichneumonidae). Diploïd males produce spermatozoa, which do not seem to be different from those produced by haploïd males. The spermatozoon is about 100 μm long, and consists of a head, 0.8 μm in diameter, and a tail 0.3 μm in diameter. Its anterior part shows an acrosomal complex, including a perforatorium and a compact and electron-dense fusiform nucleus. The postnuclear region includes a longitudinal axoneme with 2 mitochondrial derivatives. The axoneme shows 2 typical central units, 9 peripheral doublet microtubules, 9 accessory internal tubules, and 9 external microtubules with dense contents. In the testes of diploïd males, a great number of abnormal spermatozoa were observed. These spermatozoa with degenerative structures are probably not implicated in egg fertilization.     

Spermatogenesis and ultrastructure of the spermatozoa of Seison nebaliae (Syndermata)

 The spermatozoa of Seison nebaliae are characterized by an elongated sperm body, a filiform nucleus, and an anteriorly inserting external cilium with a 9×2+2 axoneme pattern. In the sperm body a frontal, middle, and hind region can be distinguished. The frontal region contains an acrosomal vesicle, a perforatorium, a basal body, and a pair of apical dense bodies; an accessory centriole is absent. The middle region is characterized by several so-called filamental plates. One large mitochondrion and one pair of accessory tubular structures are located in the middle and hind region. The hind region also contains two rows of dense bodies. Accessory tubular structures and filamental plates are autapomorphies of S. nebaliae. The shared appearance of the dense bodies in spermatozoa of species of the taxa Seison and the Acanthocephala founds their sister-group relationship, while the anterior insertion of the cilium in the spermatozoa of these taxa and in the Rotifera confirms the monophylum Syndermata Ahlrichs, 1995. Accepted: 5 August 1998     

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.     

Interspecific Variation in Structural Organisation of the Spermatozoon in the Asian Bandicoot Rats,Bandicota Species (family Muridae)

The structural organisation of the spermatozoon from two species of bandicoot rats Bandicota bengalensis and Bandicota indica was investigated by light and electron microscopy together with the effect of incubation in Triton-X 100 and sodium dodecyl sulphate. The sperm head of B. bengalensis is invariably falciform, has a uniform electron-dense nucleus capped by an acrosome with a posteriolateral equatorial segment, a subacrosomal cytoskeleton with a large rostral perforatorium, and a sperm tail, attached to the lower concave surface of the sperm head, with typical coarse fibres and fibrous sheath. By contrast, the sperm head shapes of B. indica are generally conical or bulbous, the nucleus contains a few large vacuoles, the acrosome lacks an equatorial segment, no recognisable perforatorium occurs, and the sperm tail, which is attached basally, is very short with only modest development of coarse fibres and fibrous sheath. These results indicate that, within the genus Bandicota, huge interspecific differences in morphology of the spermatozoon have evolved. The spermatozoa of B. bengalensis are similar to those of Rattus and many other murids and thus presumably represent the ancestral condition, whereas those of B. indica (and B. savilei) are unlike spermatozoa from any other eutherian mammal so far described. © 1998 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd. All rights reserved     

Ultrastructure of the spermatozoon of Myrmecocichla formicivora (Vieillot, 1881) and Philetairus socius (Latham, 1790) (Aves; Passeriformes), with a new interpretation of the passeridan acrosome

Passerine spermatozoa exhibit apomorphies that distinguish them from non‐passerine neognaths and palaeognaths. The acrosome is longer than the nucleus (excepting the suboscines, most Corvida, and a few Passerida). A perforatorium and endonuclear canals are absent. The proximal centriole is absent (except in the suboscines). The distal centriole is secondarily short, contrasting with its elongate condition in palaeognaths and Galloanserae. In the Passerida a single mitochondrial strand winds extensively along the axoneme (restricted to the anterior axoneme in suboscines and Corvida). A fibrous, or amorphous, periaxonemal sheath, seen in palaeognaths and many non‐passerines, respectively, is absent. The acrosome in Myrmecocichla formicivora and Philetairus socius is bipartite: an acrosome core is surmounted by an acrosome crest; the core is ensheathed by a layer which is a posterior extension of the crest. The acrosome helix is a lateral extension of the crest and the crest layer with (Myrmecocichla) or without (Philetairus) protrusion of material of the acrosome core into it. In M. formicivora, as in other muscicapoids, a fibrous helix is intertwined with at least the more proximal region of the mitochondrial helix. The fibrous helix is absent at maturity in Philetairus and other described passeroid spermatozoa with the possible exception of Passer italiae. In Philetairus a granular helix precedes the mitochondrial helix.     

The short spermatodesm of Arge pagana (Hymenoptera: symphyta)

In the seminal vesicle of the 'symphyta'Arge pagana the spermatozoa are stored in motile spermatodesm bundles, maintained by an anterior cap of extracellular material. This cap consists of a denser cortex and of an internal matrix, where part of the sperm heads are embedded. The number of spermatozoa per bundle is variable. The spermatozoa are short, only 30microm long, with a head region of about 23microm, and a very short flagellum of about 7microm. The head includes the acrosome, with a perforatorium, and the nucleus. The flagellum consists of an axoneme, with a 9+9+2 microtubule pattern, a centriolar adjunct, two mitochondrial derivatives and two accessory bodies. The mitochondrial derivatives are very slender and of different lengths. The longer begins at the base of the nucleus, while the shorter one starts just below the base of the centriolar adjunct. This latter is asymmetric and appears at the nuclear base, extending parallel to the axoneme up to the anterior end of the smaller mitochondrial derivative. The short spermatodesmata and the small mitochondrial derivatives characterize the A. pagana sperm. In addition, the centriolar adjunct asymmetry and the occurrence of spermatodesm bundles might be considered plesiomorphic states present in the basal Tenthredinoidea.     

Structure and ultrastructure of the spermatozoa of Bephratelloides pomorum (Fabricius) (Hymenoptera: Eurytomidae)

The spermatozoa of Bephratelloides pomorum are very long and fine. Each spermatozoon measures about 620 μm in length by 0.38 μm in diameter and, when seen under the light microscope, appears to be wavy along its entire length. The head, which is approximately 105 μm, comprises a small acrosome and a nucleus. The acrosome is made up of a cone-shaped acrosomal vesicle surrounding the perforatorium and the anterior end of the nucleus. Innumerable filaments radiate from it. The perforatorium has a diameter equal to that of the nucleus at their junction, where it fits with a concave base onto the rounded nuclear tip. The nucleus is helicoidal and completely filled with homogeneous compact chromatin. It is attached to the tail by a very long and quite electron-dense centriolar adjunct that extends anteriorly from the centriole in a spiral around the nucleus for approximately 8.5 μm. The tail consists of an axoneme with the 9+9+2 microtubule arrangement pitched in a long helix, as well as a pair of spiraling mitochondrial derivatives (with regularly arranged cristae) that coil around the axoneme, and two small accessory bodies. As well as the spiraling of the nucleus, mitochondrial derivatives and axonemal microtubules, the sperm of B. pomorum present other very different morphological features. These features include the acrosome and centriolar adjunct, both of which differentiate the spermatozoa from the majority of sperm found in other Hymenoptera. In addition these structural variations demonstrate that the sperm of chalcidoids provide characteristics that can certainly prove useful for future phylogenetic analysis at the subfamily level and, possibly, the genus too.     

Spermatozoa from the supertribes Lasiopteridi and Stomatosematidi (Insecta, Diptera, Cecidomyiidae): ultrastructure data and phylogeny of the subfamily Cecidomyiinae

Spermatozoa from seven gall-midge species, representing the supertribes Lasiopteridi and Stomatosematidi, have been examined by electron microscopy and compared to the spermatozoa of 30 previously examined gall-midge species of the subfamily Cecidomyiinae. Derived characteristics of all examined representatives of this subfamily are the lack of acrosome and the absence of accessory tubules in their axoneme. The sperm axoneme of Didactylomyia has a unique '9 + 5 pattern', i.e. with 9 outer doublets and 5 inner singlet microtubules. Unlike other members of Cecidomyiinae, Didactylomyia has retained some plesiomorphic traits, namely crystal containing mitochondria and a homogeneously condensed nucleus. Stomatosema has a 10 + 0 axoneme and an irregular nuclear condensation. Thus, Didactylomyia may serve as an useful outgroup for phylogenetic analysis within the subfamily Cecidomyiinae. The supertribe Stomatosematidi is a paraphyletic assemblage. Nearly all members of Lasiopteridi, Ozirhincus, Arnoldiola, Brachineura and Ledomyia , have a synapomorphic character in the great number of microtubules in parallel to the axoneme. A notable exception is Rhizomyia , which shares certain apomorphic traits with several genera that have previously been classified within the Cecidomyiidi, i.e. Contarinia, Allocontarinia, Lestodiplosis and Myricomyia. Moreover, these genera have a flat sperm tail and microtubular doublets located close to the cell membrane, both characteristics that differ markedly from the very peculiar sperm tail found in other members of Cecidomyiidi.
Cladistic analysis of sperm characters suggests that the supertribe Cecidomyiidi is a polyphyletic taxon and supports the existence of a sister-group relationship between the supertribe Lasiopteridi and the genera Rhizomyia, Contarinia, Allocontarinia, Lestodiplosis and Myricomyia.     

Regional differences in composition of the perforatorium and outer periacrosomal layer of the rat spermatozoon as revealed by immunocytochemistry

The rat perforatorium is the part of the perinuclear theca that underlies the acrosomic system. It appears to be composed of several polypeptides. The main objective of this study was to determine the distribution of seven of these perforatorial polypeptides in the head of the rat spermatozoon. For this purpose, polyclonal antibodies were affinity purified from these polypeptides and tested 1) for their distribution on electron-microscope sections of late spermatids and spermatozoa by immunogold labeling and 2) for their specificity on Western blots of denatured perforatorial polypeptides by immunoblotting. Immunoblotting showed that all seven of the prominent perforatorial polypeptides had epitopes in common. Immunogold labeling of spermatozoa showed that antibodies against the 13, 13.4, and 16 kDa polypeptides were restricted in their localization to the thicker apical portion of the perforatorium and to the inner zone of the ventral spur. However, antibodies against the 34, 43, 57, and 63 kDa polypeptides reacted with the entire perforatorium but, in addition, reacted with the inner part of the ventral spur and with a portion of the "outer periacrosomal layer" lying between the plasma membrane and the outer acrosomal membrane. These results suggest 1) that there are regional differences in protein composition of the perforatorium, of the outer periacrosomal layer, and of the postacrosomal dense lamina; and 2) that perforatorial polypeptides may not necessarily be restricted to the subacrosomal region, but may also compose portions of the outer periacrosomal layer and postacrosomal dense lamina. Based on both immunoblotting and immunocytochemical results, using an antiactin monoclonal antibody that recognizes all known isoforms of actin, actin was not detected in the perforatorium of step 19 spermatids or spermatozoa. Actin, however, together with the seven perforatorial polypeptides tested, was present in the subacrosomal space of elongating spermatids before the process of condensation of the perforatorium takes place.     

A dendrobranchiate, Peisos petrunkevitchi (Decapoda, Sergestidae), with reptant-like sperm: a spermiocladistic assessment

The spermatozoon of Peisos petrunkevitchi differs significantly from those of any of the investigated dendrobranchiates in the anterior fusiform acrosome, lacking a spike, and embedded in (instead of capping) the nuclear region. In contrast, the position of the acrosome and the internal arrangement of its contents, as well as the apomorphic presence of a pair of centrioles (absent in all known dendrobranchiate spermatozoa) at the base of the acrosomal perforatorium, indicate a close affinity between this sperm plan and that found in reptants, especially anomurans and brachyurans. Based on the present and previous observations on decapod spermatozoal ultrastructure, we review the phylogeny of dendrobranchiate spermatozoa in the perspective of most recent phylogenetic analyses of malacostracan crustaceans.