bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructural Aspects of Spicule Formation in the Solitary Ascidian Herdmania momus (Urochordata, Ascidiacea)
Authors: Lambert Gretchen 
Published: April 2010

AbstractThe solitary stolidobranch ascidian Herdmania momus contains numerous calcium carbonate spicules in its tunic and body tissues. The slender body spicules form inside complex sheaths in the body wall and branchial basket, where they remain for the life of the animal. The much smaller tunic spicules form inside the tunic blood vessels and then migrate to the tunic surface, where they become anchored by their spiny base. This paper is an ultrastructural investigation of the formation of the body spicules; the tunic spicules, which apparently form quite differently, will be the focus of a future study. The body spicules are composed of rows of closely packed acicular spines which form completely extracellularly. The spine tips are covered by flattened, highly pseudopodial sclerocytes bound together by tightly interdigitating cell processes. The basal regions of contiguous spines are covered by very thin sclerocyte cell processes. An organic matrix is present within the spines; its exact nature is not clear. A very dense extracellular inter‐spine matrix is located between the spine tips and the contiguous basal regions. Presclerocytes within the sheaths between the spicules are probably responsible for formation of the extracellular structures of the sheaths. The presclerocytes appear to aggregate and transform into sclerocytes at the apical end of the spicule. New spines are added at the apical end of the spicule as well as between larger spines. Comparisons are made between body spicule formation in H. momus and skeletogenesis in echinoids.
Pharyngeal and Gastrodermal Ultrastructure of Prorhynchus stagnalis Schultze, 1851 (Turbellaria, Lecithoepitheliata)
Authors: Antoniazzi Marta M. , Silveira Marina 
Published: April 2010

AbstractThe digestive tract of a freshwater Lecithoepitheliata turbellarian, Prorhynchus stagnalis, has been studied at the ultrastructural level. The buccal tube connecting the mouth opening to the pharynx is lined by an insunk epithelium, and is provided with two kinds of secretory cells. The bulbous pharynx itself, typical of the genus, is a highly muscular organ, also lined internally by an insunk epithelium; it also bears at least two different types of gland cells. Externally the pharynx is enveloped by a thin, flat epithelium. The gastrodermis consists of phagocytes and Minotian gland cells, as typical for most Tricladida. No ciliary covering was observed along the whole digestive system; instead, phagocytic cells have long microvillar projections. Preliminary attempts to follow the digestive process using external markers and cytochemical reaction for acid phosphatase were successful in demonstrating endocytic activity in the phagocytes. These data, besides being a contribution to morphology and systematics, also speak in favour of the general digestive theory of Turbellaria proposed by Jennings and serve as a starting point for experimental studies on intracellular digestion within the Lecithoepitheliata.
The Origin of the Crustacea*
Authors: Fryer Geoffrey 
Published: April 2010

AbstractPre‐Cambrian metamerically segmented bilaterians that ultimately gave rise to crustaceans probably arose from unsegmented flatworms. The recent suggestion that early arthropods, far from possessing a capacious segmented coelome of the annelid type, may never have had such, is attractive. Crustaceans were probably derived from small, segmented, surface‐dwelling non‐annelidan marine worms with a haemocoele. Their appendages probably originated as simple outgrowths whose shape was maintained by haemocoelic pressure. Possible routes whereby trunk limbs could have been derived from such rudiments are suggested. Trunk limbs would originally be unsegmented, as in many extant branchiopods and in certain Cambrian crustaceans. The evolution of thoracopodal feeding and some of the factors involved in the differentiation of the cephalic appendages are considered, as is the origin of the nauplius larva and the establishment of its feeding mechanism. Certain features of the cephalic region of the adult reflect changes necessitated as a result of the incorporation of the nauplius into the life cycle. Ontogeny would originally be anamorphic and follow the pattern preserved in its most primitive form in certain extant anostracan branchiopods. A reconstruction of the Ur‐crustacean is attempted. Justification for features not previously associated with such a reconstruction, such as locomotory antennae, a relatively short trunk with only a short series of limbs and a limbless posterior region, and unsegmented trunk limbs, is provided by fossil evidence, functional considerations and the situation in primitive extant forms. Crustaceans were evidently not derived from any known arthropod clade. Stem lineage forms probably arose from the same group of pre‐crustacean ancestors. While the Crustacea appears to be a monophyletic group, the idea that arthropodization must have occurred more than once and that the Arthropoda is a polyphyletic assemblage is supported, and evidence in favour of this view is cited.
The ‘Alum Shale Window’—Contribution of ‘Orsten’ Arthropods to the Phylogeny of Crustacea
Authors: Walossek Dieter , Müller Klaus J. 
Published: April 2010

AbstractExceptional three‐dimensional preservation of phosphatized Upper Cambrian arthropods of different groups from southern Sweden permits not only description of their morphology in full detail but also assumptions on functional morphology and life habits. Ontogenetic stages, in some cases in complete sequences, give additional information about habitual changes in the life cycle. Altogether this provides a wide data basis for phylogenetic considerations, particularly for the crustacean branch of the Arthropoda. Among the ‘Orsten’ fossils, a number could be recognized as representatives of crown‐group crustacean taxa, such as the Skaracarida and Bredocaris as members of each of the two different lineages of Maxillopoda, or Rehbachiella as a member of the Branchiopoda. Another set of forms shares some characters with the crowngroup crustaceans but lacks a large number of others. These fossils, identified as representatives of the stem line of Crustacea, provide a hitherto unknown data set for the interpretation of morphological and functional changes in the evolution towards the crown‐group of this taxon.
Origin of Maxillopoda
Authors: Newman William A. 
Published: April 2010

AbstractThe Maxillopoda Dahl (1956) was defined primarily by a 5–6–5 body plan; that is, a head supporting five pairs and a thorax six pairs of appendages, and an abdomen of five segments, the first of which may bear a pair of genital limbs and the last of which, the telson, bears caudal rami. Representatives as diverse as ostracods, cirripeds, orstenocarids and skaracarids appear in the Cambrian, so we are dealing with a radiation that in the most part took place over 500 million years ago. A progenetic origin of the maxillopodans, from an ur‐malacostracan stock, has been proposed (Newman, W. A. 1983. Crustacean phylogeny—Crustacean Issues, Vol. 1, pp. 105–119). However, new information, including the recently discovered Cambrian forms Skaracarida and Orstenocarida, the structure of spermatozoa, and preliminary results from the sequencing of ribosomal RNA, suggests that the Maxillopoda are more deeply rooted in the crustaceans than previously supposed, likely closer to the ur‐crustacean than to the ur‐malacostracan.
A Homage to Homology: Patterns of Copepod Evolution
Authors: Boxshall Geoffrey A. , Huys Rony 
Published: April 2010

AbstractLack of attention to determining the homology of character states is recognized as being responsible for the ever increasing numbers of phylogenetic schemes for the Crustacea that appear and disappear so rapidly. Detailed study of musculature, segmentation and setation of the limbs of all 10 orders of copepods revealed numerous phylogenetically informative characters, based on segmental fusion patterns and the presence of individually identified setation elements. Simple counts of limb segments (or of setae) were found to be virtually useless for constructing phylogenies in the copepods. This conclusion can probably be extended to other crustacean groups.
Aspects of Malacostracan Evolution
Authors: Dahl Erik 
Published: April 2010

AbstractThe outstanding success of the Crustacea Malacostraca is largely due to the tagmatization of the malacostracan body and its appendages, which has permitted the evolution of a wide spectrum of adaptations, particularly within caridoid taxa with series of specialized appendages. Non‐caridoid ancestral malacostracans have not materialized, and recent proposals by Schram (Schram, F. R. 1986. Crustacea), according to which the Phyllocarida should be removed from the Malacostraca and transferred to a re‐defined class Phyllopoda, was found to be built upon false premises. Manton (Manton, S. M. 1953.—Symposia of the Society for Experimental Biology 7: 339–376), discussing a hypothetical malacostracan ancestor, was of the opinion that in such an ancestor walking preceded swimming, an opinion which has received considerable support. This also implies that the Malacostraca were originally epibenthic, retaining a number of primitive features. The hypothetical ‘generalized malacostracan’ envisaged by Calman (Calman, W. T. 1909. A treatise on zoology, Part 7, pp. 1–346) was also presumed to be epibenthic, representing what Calman called a caridoid facies, thereby emphasizing an important aspect of the eumalacostracan structural and functional plan.
Co‐evolution Between Fishes and Crustaceans
Authors: Wägele J. W. 
Published: April 2010

AbstractIn aquatic ecosystems fishes are, in general, the most important predators of crustaceans. This must not have been so at the beginning of the Mesozoic. Evolution of aquatic vertebrates led from heavy, benthic, microphagous animals to buoyant, agile, omnivorous ones. Key events of this evolution took place in fresh water, while most crustacean groups probably evolved in marine habitats. It is pointed out that until early Jurassic times the caridoid escape reaction obviously ensured the survival of eucarid species, while the later radiation suggests that selection favoured well‐calcified and short‐tailed species. It is suspected that the radiation of the marine Teleostei is a main cause of this evolution. This hypothesis is in accordance with the occurrence of the most archaic crustacean relict species in fish‐free habitats.
Ultrastructure of the Spermathecae of Parafabricia ventricingulata and Three Species of Oriopsis (Polychaeta: Sabellidae)
Authors: Rouse Greg W. 
Published: April 2010

AbstractParafabricia ventricingulata females have a pair of spermathecae located in the radiolar crown anterio‐dorsal to the buccal opening. The spermathecae have three regions; an entrance, 7 μm across, leading into a ciliated ‘atrium’ that is approximately 50 μm long; a connecting piece, 2–5 μm across and 25 μm long, leading from the ‘atrium’ to the sperm receptacle. The sperm receptacle is heavily pigmented and spherical. The sperm lie in a large mass in the receptacle with no particular orientation. Oriopsis bicoloris females have a pair of unpigmented spermathecae in the collar behind the radiolar crown. Each spermatheca is a simple blind duct 100 μm long, with a lumen 8 μm in diameter. Between 30 and 40 sperm lie in the lumen of each spermatheca. Oriopsis brevicollaris females have a pair of spermathecae located in the radiolar crown above the buccal opening. From the opening, 10 μm across, a blind duct runs for 90 μm. Sperm are stored in the distal region of the duct. Sperm lie along the margins of the duct in close contact with microvilli. Up to 10 sperm were found in each spermatheca. Oriopsis mobilis females have a pair of spermathecae located in the radiolar crown above the buccal opening. The opening, 3 μm across, leads into a blind duct that runs for 30 μm. Sperm are stored in the distal region of the spermathecae where they are embedded in spermathecal cells. Between 10 and 20 sperm were found in each spermatheca. Oriopsis dentata was found not to have spermathecae.The homologies of the spermathecae found within the Sabellinae and Fabriciinae (Sabellidae) and the Spirorbinae (Serpulidae) are discussed, but cannot be resolved on present evidence.
Ultrastructure of Enteronephridia and General Description of the Alimentary Canal in Trochonerilla mobilis and Nerillidium troglochaetoides (Polychaeta, Nerillidae)
Authors: Tzetlin Alexander B. , Purschke Günter , Westheide Wilfried , Saphonov Michail V. 
Published: April 2010

AbstractThe alimentary canals of Trochonerilla mobilis and Nerillidium troglochaetoides consist of a ventral pharyngeal organ, oesophagus, stomach, intestine, and rectum. Prominent salivary glands lying lateral to the oesophagus discharge their secretions into the buccal cavity. Ciliated canals, the enteronephridia, embedded in the intestinal epithelium, open into the stomach near its border to the intestine. The ventral pharynx comprises a muscle bulb connected to a tonguelike organ by an investing muscle. The whole alimentary canal is ciliated except for the intestine of T. mobilis. The stomach is built up of absorptive cells and posteriorly also of secretory cells, whereas the intestine consists of only one cell type which is considered to be mainly absorptive. A typical microvillar brush border is present only in the intestine of T. mobilis; elsewhere the density of microvilli is low or the cells have irregular apical processes. In N. troglochaetoides the intestine has a ventral ciliary gutter laterally bordered by cells with highly specialized microvilli. The enteronephridia — 3 in N. troglochaetoides and 13 in T. mobilis — are unicellular tubes up to 130 μm long with a microvillar brush border and other cytological features typical for nephridial ducts. These structures are not known in any other polychaete taxon.
Immunocytochemical Localization of Serotonin and Neuropeptides in the Neuroendocrine Paraneurons of Teleost and Lungfish Gills*
Authors: Zaccone G. , Lauweryns J. M. , Fasulo S. , Tagliafierro G. , Ainis L. , Licata A. 
Published: April 2010

AbstractNeuroendocrine (NE) cells in the gills of six fish species were identified by serotonin and peptide immunohistochemistry. They occur either as single cells or as cell clusters within the filamental epithelium. Two populations of NE cells were identified that exhibit an immunoreactivity either for serotonin alone or for met‐enkephalin and leu‐enkephalin co‐distributed in the same cells. We demonstrate for the first time the occurrence of open‐type endocrine cells in the fish gill epithelium and confirm the presence of only serotonin‐immunopositive cells of the closed type. The NE cells of the species studied do not react positively to other neuroendocrine markers occurring in the mammalian lung. Great differences probably exist in the expression of these epitopes on antigenic structures among various animal species.Although the physiological role of neuropeptides and serotonin in the fish gill NE cells is unknown, the presence of these molecular markers is of interest not only from an evolutionary aspect, but also in terms of a potential animal model to study the supposed functions of the airway neuroendocrine system in the vertebrates.
Sensory Spots of Echinoderes capitatus (Zelinka, 1928) (Kinorhyncha, Cyclorhagida)
Authors: Nebelsick Monika 
Published: April 2010

AbstractThe sensory spots of Echinoderes capitatus from the Gulf of Trieste were examined by transmission and scanning electron microscopy. Their arrangement is bilaterally symmetrical and is species‐specific.At the cuticle surface the sensory spot appears as a rounded to ovoid area of small cuticular papillae in which two pores open. The sensory organ consists of two different sensory cells, the monociliary receptor and the collar receptor, and one sheath cell. The course of the axons and their connections to the nervous system are described.A survey of collar receptors among invertebrates is given. A comparison of the sensory spots within Kinorhyncha and a comparison with the flosculi of Priapulida and the N‐flosculi of Loricifera is made. A possible homology of these three structures is discussed.
Ultrastructure of Chrysopetalid Paleal Chaetae (Annelida, Polychaeta)
Authors: Westheide Wilfried , Russell Charlotte Watson 
Published: April 2010

AbstractPaleal notochaetae belonging to a number of Chrysopetalum species (Chrysopetalidae) were examined by scanning and transmission electron microscopy. Paleae are composed of broad medullary channels stacked with a regular series of horizontal fibrous diaphragms. The medullary part of the palea is surrounded by irregular rows of narrow tubular channels within the chaetal cortex. The origin and function of camerate chaetae is discussed.
Ultrastructure and Cytochemistry of Periostracum and Mantle Edge of Biomphalaria glabrata (Gastropoda, Basommatophora)
Authors: Bielefeld Ulrich , Peters Werner , Becker Wilhelm 
Published: April 2010

Abstract Three layers of different electron density can be distinguished in the periostracum. Periostracal units of up to 900 nm length are merged into the outer fibrous layer and binding of gold‐labelled lectin‐WGA indicates the presence of chitin because it is labile to chitinase treatment.The periostracum is formed by the epithelia of the groove and the belt at the mantle edge. The distal and basal epithelium of the groove consists mainly of type A cells with an extended Golgi apparatus and apical vesicles. The presence of peroxidase and phenol oxidase indicates a function in tanning of the periostracum. In the proximal epithelium of the groove, type B cells with protruding apices add more material for periostracum formation. Type C cells secrete single periostracal units which are formed within single vesicles or larger vacuoles. Type D cells secrete electron‐dense vesicles which also contain WGA‐positive material.The distal cells of the belt are characterized by predominating strands of the rER while subapical vacuoles, to some of which WGA binds, dominate in the cells of the central part. In the belt, phenol oxidase and peroxidase can be localized in cisternae of the rER and the Golgi apparatus. Numerous control incubations indicate that, indeed, two different enzymes are localized.
Genitalia Fitting, Mating Behaviour and Possible Hybridization in Millipedes of the Genus Craspedosoma (Diplopoda, Chordeumatida, Craspedosomatidae)
Authors: Tadler Andreas 
Published: April 2010

Abstract The functional anatomy of the extremely complex copulatory organs of the millipede Craspedosoma transsilvanicum Verhoeff, 1897, was investigated by scanning electron microscopy and serial semi‐thin sectioning after fixation of the animals by freezing in copula. There is no male organ for sperm transfer which inserts into the receptacula seminis. Sperm secretion is only brushed over the openings of the receptacula by cuticular projections of the anterior gonopods (‘brush’). Other parts of the gonopods (projections of the cheirites, podosternite) bring the brush and the openings of the receptacula in the proper position.Examination of the gonopods from series of Craspedosoma from locations near Vienna showed that there are intermediary specimens between the nominal species C. transsilvanicum and C. alemannicum Verhoeff, 1910. Obviously, a mechanical isolation mechanism, as supposed by Verhoeff, does not exist between these nominal species.At the beginning of a copulation, the male forces the female into the mating position. When touched by males, the females try to evade them by rolling up. The possibilities are discussed that females thereby test the actual fitness of males, and that males use their clasper‐like copulatory organs to prevent females from escaping.
Genital Morphology and Sperm Storage in Pholcus phalangioides(Fuesslin, 1775) (Pholcidae; Araneae)
Authors: Uhl Gabriele 
Published: April 2010

AbstractThe genital morphology of female Pholcus phalangioidesis examined to clarify the composition of the uterus externus and the place of sperm storage in this species. Two conspicuous pore plates serve as exits for glandular secretion that gets discharged into the uterus externus. The secretion accumulates close to the pore plates and to some extent in the region of the heavily sclerotized valve that separates the uterus externus from the uterus internus. During copulation, the male transfers spermatozoa and male secretions into the female genital tract where they are embedded and stored in the female secretion. As Ph. phalangioidesdoes not possess any separate sperm storage organs such as receptacula seminis, the glandular secretion serves to store and fix the sperm mass in a specific position within the uterus externus itself.
Serous Cutaneous Glands in the Tree‐frog Hyla arborea arborea(L.): Origin, Ontogenetic Evolution, and Possible Functional Implications of the Secretory Granule Substructure
Authors: Delfino G. , Brizzi R. , Calloni C. 
Published: April 2010

AbstractThe morphological evolution of the cutaneous venom during ontogenesis in the tree‐frog Hyla arborea arboreais described using light and electron microscopy. Venom biosynthesis involves the rough endoplasmic reticulum and Golgi stacks. The secretory product first appears at the hind‐limb larval stage in the form of aggregates of small granules or larger, more elaborate structures, both contained in Golgi stacks. Maturative evolution proceeds through the merging of these secretion storage bodies and leads to the remarkable morphological heterogeneity characteristic of the venom of premetamorphic larvae and juveniles. However, large structures, resulting from the aggregation of small granules arranged in a repeating pattern become the only secretory accumulation bodies found in fully developed glands. In juveniles, discrete amounts of venom were seen to be discharged through exocytosis into the exiguous gland lumen, which lies just beneath the intercalated tract. These findings strongly contrast the traditional pattern of holocrine release characteristic of anuran serous glands. The merocrine release of tiny venom particles is consistent with the regulative roles—relevant to the skin physiology—performed by component molecules of anuran cutaneous venoms.
The Ultrastructure and Functional Morphology of a Captaculum in Graptacme calamus(Mollusca, Scaphopoda)
Authors: Byrum C. A. , Ruppert E. E. 
Published: April 2010

AbstractThe structure and function of the captaculum in Graptacme calamuswere studied using light microscopy, videomicrography, and transmission electron microscopy. Graptacme calamusutilizes a longitudinal ciliary band to transport small food particles along the outstretched filament. The head of the captaculum, which bears the alveolar indentation, contains a large ganglion, at least three types of gland cells, circular and longitudinal muscles, and connective tissue. It is likely that gland 1 secretes mucus which is used in the transport of food particles and that gland 2 secretes material which promotes adhesion of the alveolus to the substratum. The function of gland 3 is unknown. Critical observation of the captaculum surface revealed that the cilia of the alveolar region have truncated tips unlike those found on other regions of the captaculum. These alveolar cilia probably aid in the distribution of adhesive substance and in adhesion.