bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spermiogenesis in a Scutariellid (Platyhelminthes)
Authors: Iomini Carlo , Ferraguti Marco , Melone Giulio , Justine Jean‐Lou 
Published: April 2010

AbstractSpermiogenesis and spermatozoa were studied by transmission and scanning electron microscopy in Troglocaridicolasp., a scutariellid epizoic on a cavernicolous freshwater shrimp. Spermiogenesis involves elongation of the spermatid in which the nucleus elongates, but remains close to the common cytoplasmic mass. Flagella first grow in opposite direction and at a right angle to the cytoplasmic shaft, and centrioles show associate structures. Later, the two centrioles rotate and the flagella emerge parallel, but still perpendicular to the shaft. An apical process elongates at the extremity of the spermatid shaft. The spermatozoon shows active flagellar beating and undulations of the sperm body. The spermatozoon comprises an anterior ‘corkscrew’ region, the flagellar insertion region, a cytoplasmic region and a posterior nuclear region. The corkscrew contains an electron dense structure, not membrane‐bound, originating from the apical process of the spermatid. The flagella show the 9+‘1’ pattern, usual in Platyhelminthes. The cytoplasmic and nuclear regions show a cortical row of about 50 twisted longitudinal microtubules surrounding a row of electron dense, and not membrane‐bound, 25‐nm granules. These granules are original structures and seem to be known only in a few Platyhelminthes species in which a non‐flagellar movement of the spermatozoon occurs. Thus, it is hypothesised that the 25‐nm granules play a role in cellular motility. Sperm ultrastructure in Troglocaridicolashows major differences to that in the temnocephalids. It is therefore concluded that the phylogenetic position of the scutariellids within the Temnocephalidea should be reinvestigated.
Morphology of the Luminous Organ of the Squid Loligo duvaucelid'Orbigny, 1839
Authors: Pringgenies Delianis , Jørgensen Jørgen Mørup 
Published: April 2010

AbstractThe present paper deals with the morphology of the luminous organ of the squid Loligo duvauceli, caught in the sea off Indonesia and Thailand. Two luminous organs are situated on the ventral surface of the ink sac, near the anus. Each organ consists of a luminous sac divided into numerous discrete chambers containing bacteria. On the ventral side the organ is bordered by a lens‐like structure, consisting of muscle cells. On the remaining sides the bacterial chambers are limited by a cup‐shaped reflector layer with numerous parallel lamellae. The reflector separates the bacterial chamber from the ink sac. A ciliated channel connects the interior of the bacterial chamber with the mantle cavity.
Scanning Electron Microscopy of Mouth Appendages in Six Species of Barnacles (Crustacea Cirripedia Thoracica)
Authors: Høeg Jens. T. , Karnick Elisabeth S. , Frølander Amy 
Published: April 2010

AbstractThe morphology and setation of mouth appendages (trophi) are investigated with scanning electron microscopy in the balanomorph barnacles Semibalanus balanoides, Balanus balanusand B. nubilusand in the pedunculate barnacles Pollicipes polymerus, P. cornucopiaand Lepas anatifera.It is difficult to uphold a clearcut distinction between denticles and setae and several types of setae also intergrade with each other. The trophi of Pollicipes polymerusand P. cornucopiahave the most ‘generalized’ morphology. The palps of Pollicipesand L. anatiferaare simpler than those in balanomorphs and carry a single type of seta. In L. anatiferathe mandibles and maxillules are adapted to a semi‐predatory feeding habit by carrying large, pointed teeth, but this species lacks the foliate‐serrate setae which populate the palps in the other species studied. Compared with Pollicipesand Lepas, the three balanomorphs have palps with a complex setation. The trophi in S. balanoidesdiffer from the two species of Balanusin numerous features of setation and denticulation, notably in having the palps populated by plumodenticulate setae homologous to purely denticulated types in Balanus.It is suggested that SEM studies of barnacle trophi will provide characters of use in estimating phylogeny.
The Evolutionary Origin and Homologues of the Supracochlear Lamina: a Contribution to our Knowledge of Mammalian Ancestry
Authors: Bjerring Hans C. 
Published: April 2010

AbstractIn cetaceans, each otic capsule is bound anteriorly to the remainder of the endocranium by an aliform structure called the supracochlear lamina. This lamina has been established here as the homologue of the sphenocochlear commissure of other mammals. Most researchers believe that these two structures arose within mammals. However, a comparative study involving data from both extant and extinct craniates suggests that the supracochlear lamina and the sphenocochlear commissure have a long premammalian history. The conclusion is that the lower of the two pharyngeal segments at the upper end of the mandibular branchial arch first became incorporated in the endocranium, constituting the cartilago trabecularis in the embryos of jawed craniates. The distal, or posterior, extremity of the trabecular cartilage projected outwardly to form the basitrabecular process. This process, which when ossified is called the processus basipterygoideus, functioned as a jaw support. Later, one more jaw support, termed the basivincular, evolved immediately in front of the basipterygoid process. Both these supports for the upper jaw existed in the piscine forerunners of the tetrapods. Subsequently, in the lineages leading to mammals, the basivincular jaw support became the processus alaris to which is attached an upper jaw endoskeletal remnant, called the ala temporalis. The basipterygoid jaw support, however, vanished as a consequence of the evolution of an exoskeletal joint system for the jaws of mammals. Yet the basipterygoid process persisted and as the sphenocochlear commissure or the supracochlear lamina assumed the new function of supporting the cochlear part of the auditory capsule.
Comparative Morphology and Function of Hepatic Caeca in Four Enteropneusts
Authors: Bridges Todd S. , Woodwick Keith H. 
Published: April 2010

AbstractA morphological and functional study was made of the hepatic region in four enteropneust hemichordates: Schizocardiumsp., Ptychodera flava, Ptychodera bahamensis, and an undescribed ptychoderid from Maui, Hawaii, using light and electron microscopy. The hepatic region of these enteropneusts, as well as others, is characterized by a brown‐green color and the presence of numerous caeca which represent dorsal extensions of the gut. These caeca extend above the dorsal surface of the worm and are organized into bilateral rows. Species‐specific differences were noted in the organizational pattern of the sacculations within rows and the morphology and histology of individual sacculations. Numerous brown‐green vesicles were discovered in both the epithelial cells and lumen of sacculations. Transmission electron microscopy revealed these bodies to be heterophagic vacuoles and residual bodies. Morphological evidence suggests that hepatic caeca are involved in intracellular digestion. Once endocytosed food particles are packaged as heterophagic vacuoles, and digestion has been completed, the residual bodies are packaged together and exuded from the cell in a spherule of cytoplasm.
The Spermatozoon of Brachionus plicatilis(Rotifera, Monogononta) With Some Notes on Sperm Ultrastructure in Rotifera
Authors: Melone Giulio , Ferraguti Marco 
Published: April 2010

AbstractThe spermatozoon of B. plicatilisis a thread–like cell with an anterior flagellar portion and a posterior cell body. The flagellum has a lateral ‘undulating membrane’, containing a folded longitudinal cisterna and an axoneme. The basal body of the axoneme is at the anterior tip. The axoneme lacks outer dynein arms and extends through the entire flagellar region and most of the cell body. The main portion of the flagellum and of the cell body contains a series of vesicles with tightly packed tubules that may serve as a cytoskeleton. The cell body contains a partly condensed nucleus, several mitochondria and some cytoplasm. Some elongated mitochondria are arranged in the postnuclear region. When the spermatozoon moves, the undulations propagate from the basal body at the flagellar tip. Late spermatids can be recognized by the nucleus and the flagellum being coiled and enclosed within a common cell membrane. As in other rotifers, there are cigar–like cell products (‘rods’) in the testes. The general organization of the cell, including the absence of an evident acrosome, resembles that of the other known monogonont sperm types.
The Structure of the Spermatozoon of the Japanese Quail, Coturnix coturnix L., var. japonica
Authors: Woolley D. M. 
Published: April 2010

AbstractThe spermatozoa of the Japanese quail conform, in their general ‘sauropsid’ plan, to that of other non‐passerine birds. They are notable, however, in that the flagellum is very elongated (208 μm) and carries approximately 2,500 mitochondria in an extensive midpiece. Ultrastructurally, the acrosome and acrosome‐nucleus junction is exactly as reported for other galliform birds. The neck region contains two centrioles arranged almost in‐line; this unusual layout apparently occurs also in guinea fowl sperm. At the tip of the axoneme, beyond the termination of the central pair microtubules, is a structure—the tip granule—previously recognized in sperm of the domestic fowl. Trypsin digestion splits the axonemal cylinder, and the doublets then spiralize. This response has been reported before, in the sperm tails of other avian species.
Classification, Based on Autonomous Fluorescence, of the Blood Cells of Several Ascidians that Contain High Levels of Vanadium
Authors: Wuchiyama Junko , Michibata Hitoshi 
Published: April 2010

AbstractAscidians are known to have the unique ability to accumulate vanadium in their blood cells. Classification of the various types of blood is, however, the subject of some controversy. In the present study we found that the various types of blood cell can be classified on the basis of their autonomous fluorescence upon excitation with blue‐violet light. This method was of particular practical value in the classification of the vacuolated cells that account for about 80% of the total population of cells and are distinguished by their ability to accumulate vanadium.
The Parietal Problem: How to Cut This Gordian Knot?
Authors: Bjerring Hans C. 
Published: April 2010

AbstractAlthough no one has disputed that the piscine progenitors of the tetrapods have a homologue of the human parietal bone, opinions differ as to where in the skull roof this homologue is located. One view holds it to be either of two interorbital bones that together surround the foramen neuroepiphysium (and the so‐called pineal plates); another, that it is each of the two mesial bones which comes next in order, behind the orbital cavities. Both of these views are untenable because neither of the proposed bones has proved to be amenable to conversion to the parietal bone of man. In seeking a solution to this issue thoughts turn to the tentorium cerebelli, whose topographic relationships and comparative morphology place it in the key position as a plausible derivative of the posterior half of the cranium of the tetrapod forerunners. Following this line of reasoning, it can be suggested that the tentorial exoskeleton, here called the pluteal bones, originally was situated in the dermis superjacent to the synotic tectum. In early therian phylogeny, these skull bones were covered by the backwardly expanding cerebral hemispheres which, concomitantly, became overgrown and thus protected by epiotic exoskeleton. It follows that the likely homologues of the human parietal bones are those parts of the skull roof of the piscine progenitors of the tetrapods that lie dorsolateral to the otic capsules.
A Comparative Structural Study on Bacterial Symbioses of Caribbean Gutless Tubificidae (Annelida, Oligochaeta)
Authors: Giere Olav , Nieser Christiane , Windoffer Reinhard , Erséus Christer 
Published: April 2010

AbstractThe bacterial symbiosis in 13 different species of the gutless phallodriline genera Inanidrilus and Olavius (Tubificidae, Oligochaeta) from Carrie Bow Cay (Belize), Florida and Bermuda is structurally compared. The result is an essentially consistent symbiotic pattern regarding the position and ultrastructural design of the prokaryotic partners and their integration in the anatomy of the animal hosts. Based on numerous micrographs, it is calculated that the endobacteria comprise about 25% of the host's volume. This corresponds to at least 0.6 × 106 bacterial cells per worm of (fixed) 6 mm length, a figure that underlines the high nutritive importance of the bacteria in this symbiotic association. This importance is also endorsed by the percentage of bacteria in digestion (on average 8–10%, up to 24%) by the phagocytotic epidermal cells of the host. The symbiosis always involves two different morphological types of bacteria, apparently without intermediate stages. Detailed biometrical analyses demonstrate the significantly different size ranges of the two morphotypes, even though in two of the species, the normally rod‐shaped Type S‐bacteria are much longer than usual. About 1% of the larger, oval ‘Type L’ is regularly found in division; in some sections, this value can reach 11%. Formation of sulfur‐containing globules in this type was proven by histochemical analysis. The trophic relevance of the symbiosis is considered. Zoogeographical and evolutionary implications of the observed consistency in the symbiotic pattern in all the species studied are discussed.
Copulatory Mechanism in Holocnemus pluchei and Pholcus opilionoides, With Notes on Male Cheliceral Apophyses and Stridulatory Organs in Pholcidae (Araneae)
Authors: Huber Bernhard A. 
Published: April 2010

AbstractHuber, B. A. 1994. Copulatory mechanism in Holocnemus pluchei and Pholcus opilionoides, with notes on male cheliceral apophyses and stridulatory organs in Pholcidae (Araneae).—Acta Zoologica (Stockholm) 76: 291–300.The pholcid spiders Holocnemus pluchei (Scopoli, 1763) and Pholcus opilionoides (Schrank, 1781) are investigated with respect to functional morphology of their genital organs using freeze‐fixation of spiders during copula in liquid nitrogen and subsequent preparation of histological serial sections of the copulatory organs in functional contact. Special attention is paid to the mode of male pedipalpal arrestation before copulation, which is achieved in two quite different ways: in Pholcus by contact of the lateral cheliceral apophysis with the pedipalpal trochanter‐apophysis, in Holocnemus by locking the pedipalpal trochanter between chelicera and pedipalpal coxa. The condition in Pholcus is considered to be apomorphic and to present a synapomorphy of about a dozen genera for which the name “Pholcus‐group” is proposed. The stridulatory apparatus of Holocnemus pluchei is described, its biological significance discussed and an overview of accounts on stridulation in Pholcidae given.
Anatomy of Laevipilina antarctica, a Monoplacophoran Limpet (Mollusca) from Antarctic Waters
Authors: Schaefer Kurt , Haszprunar Gerhard 
Published: April 2010

Abstract The anatomy of the neopilinid limpet Laevipilina antarctica is described on the basis of reconstructions of semithin serial section. In general the anatomy of this small (3.2 mm) species resembles those of Neopilina galatheae (37 mm) and Vema ewingi (27 mm); small differences occur in the alimentary tract. Corrections of the original descriptions of neopilinid anatomy concern the structure of the mantle margin, the presence and interpretation of cephalic appendages, and details of the nervous system. The excretory organs are clearly separated from each other and there is no connection with the pericardium. The neopilinid ctenidia are considered as ventilatory rather than respiratory organs.These corrections and clarifications of the neopilinid anatomy provide an improved database for discussion on monoplacophoran affinities. In contrast to popular statements about “living fossils”, the extant Tryblidiida (Neopilinoidea) are regarded as a considerably modified and specialized early conchiferan branch.
Nervous System of the Larva of the Ascidian Molgula citrina(Alder and Hancock, 1848)
Authors: Vorontsova M. N. , Nezlin L. P. , Meinertzhagen I. A. 
Published: April 2010

AbstractFeatures of the nervous system, especially those of the peripheral nervous system, are described in the larva of Molgula citrina. In the peripheral nervous system, antibodies raised against acetylated α–tubulins mark a pair of rostral nerves arising from 8 to 10 sensory cells in the trunk epithelium, and a pair of tail nerves. In the sensory vesicle of the trunk, a pair of antennal cells is associated with the statocyte, and a tuft of ca. 150 cilia is labelled inside the hypophysial duct. A dorsal bundle of fibres forms a plexus over the surface of the sensory vesicle which extends caudally over the visceral ganglion. The latter contains somala that were back‐filled by Co2+–lysine through the cut tip of the tail. Antibodies directed against the transmitter candidates: peptides substance P, FMRFamide, somatostatin, neuropeptide Y, CGRP, VIP, and the amines: 5‐HT, dopamine, noradrenaline and GABA, all failed to demonstrate immunoreactivity anywhere in the nervous system. The trunk epithelium is ciliated uniformly but lacks papillae; this is remarkable given the presence of rostral nerves. The latter are presumed to be sensory, and can be compared with those in larvaceans and the larva of amphioxus. Sensory cells in the tail nerve, if present, lack cilia. The tail nerves are lateral in this species and presumed to be motor. © 1997 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd
Ultrastructure of the Cuticle of Loricifera and Demonstration of Chitin using Gold‐Labelled Wheat Germ Agglutinin
Authors: Neuhaus Birger , Kristensen Reinhardt Møbjerg , Peters Werner 
Published: April 2010

AbstractThe pharyngeal and lorical cuticles of adult and larval Loricifera were investigated by transmission electron microscopy. LR White sections of larval and adult Loricifera were labelled with the lectin wheat germ agglutinin (WGA) conjugated to colloidal gold. The pharyngeal cuticle of Nanaloricus mysticusexhibits a multilaminate epicuticle and an amorphous basal layer with osmiophilic fibres. The lorical cuticle consists of an osmiophilic or trilaminate epicuticle, one to three amorphous layer(s), and a basal fibrous layer which is strongly labelled by the lectin‐gold conjugate. Chitinase treatment or competitive inhibition with N‐, N′‐, N″‐triacetylchitotriose exclude labelling almost completely, whereas competitive inhibition with N‐acetyl‐D‐glucosamine does not affect labelling intensity. The binding of WGA in connection with competition experiments indicates the presence of chitin in the fibrous layer. In most areas of a section, three amorphous layers extend below the epicuticle of the Nanaloricidae. Only in favourably orientated sections can all three “amorphous” layers be seen to be formed by stacks of lamellae. Modified articulation sites with bundles of osmiophilic longitudinal fibres and an osmiophilic plate (Nanaloricidae only) occur in adult Loricifera, but not in the larval stages. The ultrastructure of the lorical cuticle of the Loricifera resembles that of other Nemathelminthes (= Aschelminthes). The morphology of the articulation sites and the number of lorical plates seem to differ between the Loricifera and Priapulida. Therefore, it is currently not possible to conclude whether the lorica of the Loricifera and Priapulida are homologous structures. © 1997 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd.
Spermiogenesis in Paratomella rubra(Platyhelminthes, Acoela): Ultrastructural, Immunocytochemical, Cytochemical Studies and Phylogenetic Implications
Authors: Raikova Olga I. , Falleni Alessandra , Justine Jean‐Lou 
Published: April 2010

AbstractSpermiogenesis and sperm structure of the primitive acoel Paratomella rubra from the Ligurian Sea, Italy, were investigated by several methods. During spermiogenesis, after flagellar incorporation by formation of two longitudinal lateral grooves, spermatid elongation is characterized in Paratomellaby the presence of four membranes encircling each axoneme plus two membranes encircling both the axonemes and the nucleus. These structures were interpreted as being three cytoplasmic canals situated one inside the other. The filiform spermatozoon has two incorporated axonemes of 9+2 type, a nucleus almost as long as the sperm cell itself, a single elongate mitochondrion, and two types of membrane‐bound granules, respectively, small and gastrula‐shaped, and large. Organelles are highly ordered, the sperm is bilaterally symmetrical with a single long mitochondrion on the ventral side and a regular row of large granules, for some length embedded in the nucleus, on the dorsal side. Immunocytochemical studies and the use of fluorescent nuclear dyes reveal the spatial relationships of the axonemes with the nucleus. The granules were shown by Thiéry, PTA and enzyme digestion tests to contain glycoproteins and/or polysaccharides and very little protein. Glycogen particles were detected in the cytoplasm. Cells containing coiled spermatozoa undergoing resorption were found in the parenchyma. New apomorphies of the taxon Paratomellabased on sperm structure are proposed: a very long nucleus, a highly bilaterally symmetrical pattern of organelles, a single long mitochondrion. These characters are not found in other Acoela, and particularly in Hesiolicium, sometimes considered closely related to Paratomella. © 1997 Published by Elsevier Science Ltd on behalf of The Royal Swedish Academy of Sciences.
Ultrastructure of Nuchal Organs in Polychaetes (Annelida) — New Results and Review
Authors: Purschke Günter 
Published: April 2010

AbstractNuchal organs are epidermal sensory structures present in most polychaetes. They are situated at the posterior edge of the prostomium and may extend posteriorly onto the peristomium. Although there is considerable external variation, they all consist of ciliated supporting cells, bipolar primary sensory cells and retractor muscles. They are innervated directly from the brain by paired nerves. The sensory cells are usually monociliated; their sensory processes lie in subcuticular spaces, the olfactory chambers. Structural variability is to be observed in the location of the sensory cells, the course of the nuchal nerve, position of nuchal ganglia as well as in cytological features of sensory and supporting cells. These differences provide useful characters for phylogenetic considerations to establish supraspecific taxa within the phylogenetic system of the Annelida. Special emphasis is laid on the problem of whether the nuchal organs represent an autapomorphy of the Polychaeta or the Annelida and thus whether the lack of nuchal organs in Clitellata is primary or secondary. As is discussed, the probability of a loss of the nuchal organs in Clitellata is higher, which favours the second hypothesis: that nuchal organs are part of the ground pattern of the Annelida and very likely are an autapomorphy of this group.
Spermiogenesis in Three Species of Whitefly (Homoptera, Aleyrodidae)
Authors: Bào Sönia N. , Kitajima Eillot W. , Callaini Giuliano , Lupetti Pietro , Dallai Romano 
Published: April 2010

AbstractAflagellate and immotile spermatozoa of three species of whitefly, Bemisia tabaci, Dialeroudes citriand Trialeroudes vaporariorum(Aleyrodidae), are described. In these three species, axoneme and mitochondria are present in the early spermatid, but degenerate in the later stages. The acrosome has arborescent appendages that almost completely surround the spermatozoan. In D. citrithe acrosomal projections are more elongated and branched than in T. vaporariorumand B. tabaci. Nuclear and cell elongation appear to occur in the absence of microtubules.