bluuebunny/crossref_metadata_2025 huggingface dataset:
The Origin of the Crustacea*
Authors: Fryer Geoffrey
Published: April 2010

Pre‐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

Exceptional 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

The 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

Lack 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

The 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

In 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

Parafabricia 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

The 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

Neuroendocrine (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

The 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

Paleal 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.
A Distinctive Nerve Cell Type Common to Diverse Deuterostome Larvae: Comparative Data from Echinoderms, Hemichordates and Amphioxus
Authors: Lacalli T. C. , West J. E.
Published: April 2010

Abstract The larval ciliary bands of echinoderm bipinnaria and pluteus larvae and the hemichordate tornaria contain similar multipolar or bipolar nerve cells with unusual apical processes that run across the surface of the band between the bases of its cilia. We report on some distinctive ultrastructural features of these cells. Among these are specialized junctions that occur between the cells' apical processes and adjacent ciliary band cells near the base of each cilium. Such structures are best developed in pluteus larvae. Many nerve cells in the larval spinal cord of amphioxus also have large apical processes that cross the central lumen of the cord. We interpret our observations on these cells in terms of Garstang's hypothesis, which derives the chordate neural tube from a larval ciliary band, and suggest that multipolar cells like those in echinoderm and tornaria bands may be the antecedents of some categories of neurons in the chordate spinal cord.
On the Microanatomy of the Cephalic Nervous System of Nereidae (Polychaeta), with a Preliminary Discussion of Some Earlier Theories on the Segmentation of the Polychaete Brain
Authors: Orrhage Lars
Published: April 2010

Abstract Earlier papers dealing with the microanatomy of the nereid brain have been studied. On this basis a re‐investigation of the cephalic nervous system and of the innervation and homologues of the anterior end appendages of these animals appeared necessary: the existing literature proved insufficient for detailed comparisons with other polychaete families and many earlier statements were quite contradictory. In the present paper, the brain commissures and the innervation of, inter alia, the antennae and the palps of Neanthes virens and Nereis pelagica are described. Special attention was paid to the roots of the circum‐oesophageal connectives and the ganglia in this part of the nervous system. The results, summarized in schematic diagrams and tables, are compared with corresponding observations in 14 other polychaete families. In a discussion of the architecture of the polychaete nervous system as a phylogenetic instrument, the supposed segmentation of the polychaete brain is questioned and the idea that the configuration of the polychaete nervous system offers support to the cyclomer theory is rejected. Other conclusions concerning the relationships within the Polychaeta are pointed out.
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.
Correlation Between the Mesodermal Male Genital Ducts and the Spermatophore Structure in a Ditrysian Moth, Zygaena trifolii (Esper, 1783) (Insecta, Lepidoptera, Zygaenidae)
Authors: Fänger Harald , Naumann Clas M.
Published: April 2010

Abstract The mesodermal male genital system and the spermatophore of Zygaena trifolii (Insecta, Lepidoptera, Zygaenidae) have been studied histologically. Whereas the long unpaired duct, the ductus mesospermaticus, has been found to consist of at least six distinctly different regions, the tissues and secretions of the seminal vesicles and the accessory glands were found to be quite uniform. Several of the different regions are separated from each other by epithelial septa (constrictions). The external structure and the internal organization of the spermatophore are described. Based on histological comparisons, the correlation between the contents of the spermatophore and the different parts of the male system is given.
Ultrastructure of Presumed Ocelli in Parenterodrilus taenioides (Polychaeta, Protodrilidae) and their Phylogenetic Significance
Authors: Purschke Günter , Jouin‐Toulmond Claude
Published: April 2010

Abstract Three different types of presumed unpigmented ocelli have been found in the anterior end of Parenterodrilus taenioides, a small gutless interstitial polychaete. The type‐1 ocelli are located in the palps and four ocelli have been found along the length of each palp. The type‐2 and type‐3 ocelli lie close together in the head segment and are located in posterior ganglionic expansions of the brain. There is one pair of the minute type‐2 ocelli but at least two pairs of the type‐3 organs, which are the largest ocelli. In each ocellus the sensory cells are of the ciliary type and possess two cilia whose plasma membranes branch into numerous microvilli. With the exception of the type‐1 ocelli they consist of a sensory cell and a supportive cell. In each ocellus the supportive cell forms a thin cup‐shaped envelope around the densely packed ciliary branches. The type‐1 ocelli consist of a single cell forming an intracellular vacuole (phaosome) which contains less densely packed microvillus‐like structures. In particular, the structure of these ocelli is compared with that in other polychaetes, with special emphasis on the remaining genera of the Protodrilida.
Haplopodous Diplopods: A New Type of Millipede Body Construction Discovered in Cambalopsid Juveniles (Diplopoda, Spirostreptida)
Authors: Enghoff Henrik
Published: April 2010

AbstractEarly juvenile stadia are described in four species of family Cambalopsidae.Hypocambala helleriSilvestri, 1897, andH. anguinea(Attems, 1900) show normal relationships between numbers of podous and apodous rings, and numbers of leg‐pairs.Glyphiulus granulatus(Gervais, 1847) andTrachyiulus tjampeanus(Attems, 1903) have a deviating stadium (probably stadium III) in which most of the podous rings (10–13 rings inG. granulatus, 19 rings inT. tjampeanus) have only one leg‐pair. No trace of the anterior leg‐pair, nor of its sternum, could be found in these rings. At the moult to the next stadium (?IV), the normal, diplopodous condition is restored. The term haplopodous diplopods is suggested for the deviating juveniles ofG. granulatusandT. tjampeanus.The haplopodous condition creates potential problems for palaeontology and indicates a closer relationship betweenGlyphiulusandTrachyiulusthan reflected in current classifications.
Morphology of the Midgut–Hindgut Juncture in the Ghost Shrimp Lepidophthalmus louisianensis (Schmitt) (Crustacea: Decapoda: Thalassinidea)
Authors: Felder Darryl L. , Felgenhauer Bruce E.
Published: April 2010

Abstract Unique morphological structures occur near the midgut–hindgut juncture in decapod crustaceans, and neither their fine structure nor function are well understood. In the ghost shrimp Lepidophthalmus louisianensis. structures associated with this juncture include an elongate posterior midgut caecum (PMGC) extending into the abdominal hemocoel, a massive swelling of acinar glands encasing the juncture, and a dorso‐lateral valve complex involving cuticularized lumenal surfaces of the anterior hindgut. Vivisection, histological studies (LM, TEM) and paraffin‐carving (SEM) have been applied to reconstruct morphology of these components and characterize constituent tissues. The lumen of the PMGC is lined by very elongate columnar cells underlain by a thin layer of circular muscle. The hemocoelic surface of the PMGC is covered by cells richly endowed with unique lamellar bodies. The acinar glands are composed of multiple rosettes of secretory cells, from which products appear to empty into the anterior extreme of the hindgut. The dorso‐lateral valve complex of the hindgut consists of anterior and posterior components, differing in strength of lumenal ridging and microdentition of the cuticular lining. Unique features of these structures may relate to behavioral, feeding and metabolic adaptations in this obligate fossorial crustacean.
Comparative Study of the Lateral‐line System of the Three‐spined Stickleback (Gasterosteus aculeatus) and the Nine‐spined Stickleback (Pungitius pungitius)
Authors: Honkanen Tapio
Published: April 2010

Abstract The morphology of the lateral‐line system of the nine‐spined stickleback (Pungitius pungitius) and the three‐spined stickleback (Gasterosteus aculeatus) has been studied. In the nine‐spined stickleback, a preopercular, infraorbital, supraorbital, postotic and peduncular canal can be identified on both sides of the body. Replacement lines are found as a continuation of the preopercular and infraorbital canal. In addition, lines of free neuromasts are found on the mandible and trunk. An accessory line is present above and below the peduncular canal. The presence of both canals and accessory lines on the peduncle suggests that the peduncle in this species has important sensory functions. No canals are found in the three‐spined stickleback. Instead, replacement lines corresponding to the canals can be identified on the head. Accordingly, the lateral‐line system of the three‐spined and the nine‐spined stickleback has a different structure. The lateral‐line system of both species shows signs of specialization but the three‐spined stickleback has a more specialized lateral‐line system than the nine‐spined stickleback.
Genital Morphology and Sperm Storage in Pholcus phalangioides(Fuesslin, 1775) (Pholcidae; Araneae)
Authors: Uhl Gabriele
Published: April 2010

The 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

The 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

The 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.
Ultrastructural study of the Central Nervous System of Endemic Geocentrophora(Prorhynchida, Platyhelminthes) from Lake Baikal
Authors: Böckerman Inger , Reuter Maria , Timoshkin Oleg
Published: April 2010

The ultrastructure of the central nervous system of four species of the Geocentrophoragroup (Prorhynchida, Lecithoepitheliata) has been studied with Geocentrophora waginias a model organism. This is the first ultrastructural study of the nervous system in flatworms of the endemic Geocentrophoragroup from Lake Baikal.

The neurons are characterized by invaginations of the plasma membrane with extracellular material (ECM) extending deep into the neuronal cytoplasm. Two types of neuron are distinguished on the basis of the character of the cytoplasm and the content of neuronal vesicles. Several more vesicle types are observed in the nerve processes in the neuropile.

The following kinds of neuronal release sites are distinguished: single synapses, shared synapses, nonsynaptic release sites characterized by omega profiles and neuromuscular contacts. Special features of the synapses in the species of Geocentrophoraare pronounced local thickenings of the presynaptic membrane connected to paramembraneous densities. The ECM‐filled invaginations and the local presynaptic thickenings are features that distinguish the neurons of Geocentrophoraspp. from previously described turbellarian neurons.
The Cytoskeletal Proteins Actin and Tubulin in the Spermatozoa of Four Decapod Crabs (Crustacea, Decapoda)
Authors: Tudge C. C. , Justine J.‐L.
Published: April 2010

The mature spermatozoa of four species of European decapod crabs (Clibanarius erythropus, Maja squinado, Cancer pagurusand Potamon fluviatile)have been investigated using indirect immuno‐fluorescence techniques for the presence of the cytoskeletal proteins actin and tubulin. Indirect immunofluorescence labelling with monoclonal anti‐actin antibody and three different monoclonal anti‐tubulin antibodies indicate that actin is present in the spermatozoa of all four species, but tubulins are restricted to the two species with microtubular arms, Clibanariusand Maja.The pattern of actin fluorescence varies between the spermatozoa of the four species, with Majaand Cancershowing intense fluorescence in the acrosome vesicle and in elements of the sperm cell involved in the acrosome reaction. The spermatozoon of each species is described ultrastructurally using transmission electron microscopy and correlations made between observed patterns of fluorescence and the cellular components described. No obvious filamentous actin (F‐actin) is visible in the electron micrographs of the spermatozoa of any of the species. In most cases the fluorescence is sufficiently specific to indicate in which region of the mature sperm cell the actin and tubulin occurs. Actin is acrosomal in Maja, Cancerand Potamonbut appears to be cytoplasmic in Clibanarius, while the tubulins appear only to be present in the cytoplasm of Clibanarius, Majaand Cancer.
Muscle Fiber Types in the Pectoralis of the White Pelican, a Soaring Bird
Authors: Rosser Benjamin W. C. , Waldbillig Donna M. , Wick Macdonald , Bandman Everett
Published: April 2010

The pectoralis muscle (M. pectoralis) of many premier soaring birds contains a smaller, accessory, deep belly in addition to the much larger superficial belly found in all flying birds. Here we describe the muscle fiber types in both the superficial and deep bellies of the pectoralis of one such adept soaring species, the white pelican (Pelecanus erythrorhynchos).Histochemical techniques are used to demonstrate both nicotinamide adenine dinucleotide (reduced) and myofibrillar adenosine triphosphatase activities within the muscle fibers. Immunocytochemical methods employing several monoclonal antibodies, each directed against a different myosin heavy chain epitope of the chicken, are also used to characterize the fibers. While the superficial belly of the muscle consists entirely of fast‐twitch oxidative‐glycolytic fibers, the deep belly is composed exclusively of slow fibers. These slow fibers are labelled by two different antibodies specific for chicken slow myosin. We suggest that the fibers of the superficial belly are best suited to flapping flight, and that the fibers of the deep belly would be recruited only during soaring flight. Furthermore, we hypothesize that the deep belly found in the pectoralis of soaring species probably evolved from a deep neuromuscular compartment of the superficial belly.
Copulatory Mechanics in the Funnel‐web Spiders Histopona torpidaand Textrix denticulata(Agelenidae, Araneae)
Authors: Huber Bernhard A.
Published: April 2010

The functional morphology of the copulatory organs of Histopona torpida(C. L. Koch, 1834) and Textrix denticulata(Olivier, 1789), investigated by semi‐thin serial sectioning after freeze‐fixation of the animals in copula, is described. In H. torpida, the long embolus runs through a precisely defined course in the membraneous genital pouch of the female vulva. The patellar apophysis locks the pedipalp in the female epigastric furrow. In T. denticulatathis is accomplished by the retrolateral tibial apophysis that gets hold at the female scape. In both species the conductor has a locking as well as a guiding function for the embolus. A comparison with previously investigated agelenids shows a surprising diversity in the function of the retrolateral tibial apophysis.
Atypical Chordoid Structures in the Aristotle's Lantern of Regular Echinoids
Authors: Bonasoro Francesco , Carnevali M. Daniela Candia
Published: April 2010

Regular sea–urchins, as a rule, prepare and process their food as pellets in their buccal cavity before ingesting them. This is obtained through the synergistic interaction of the five teeth with five fleshy protuberances (paradental tongues) which extend into the oral cavity and work like tongues. Each of these structures consists of two anatomically distinct parts: the outer component is a deep pouch of the terminal tract of the pharynx and shows a histological organization similar to that usually shown by the pharyngeal wall itself. The deeper component (paradental axis) is represented by a supporting rod and shows a peculiar histological structure, which consists of glycogen containing vesiculate cells mixed to slim muscle fibres and held together by a thin fibrillar stroma. The paradental axes are very problematic structures in terms of comparative anatomy and phylogenetic aspects. Their microscopic and submicroscopic organization is unusual for an echinoderm and recalls that of different types of chordoid organs commonly found in other invertebrates (Protostomata and Deuterostomata).
The Olfactory Organ of the Hardhead Sea Catfish, Arius felis (L.): Gross Morphology and Fine Structure
Authors: Zeiske Eckart , Theisen Birgit , Breucker Haide
Published: April 2010

The olfactory organ of the hardhead sea catfish, Arius felis(L.), was investigated morphologically by means of light and electron microscopy (SEM, TEM). The two rather large nostrils of each side lie close together, surrounded by upstanding margins. The olfactory rosette consists of a midline raphe with two rows of lamellae. The sensory epithelium on the lamellae is almost continuous and contains receptor cells of both the ciliated and the microvillous type. Ciliated non–sensory cells are scattered throughout the sensory epithelium. Accessory ventilation sacs are lacking. The shape, position and size of the nostrils indicate that forward motion of the fish creates the water current through the olfactory organ (kolymbosmates). The scattered non–sensory cilia may aid in ventilation. The olfactory organ of A. felisdiffers from that of the other marine catfish, Plotosus lineatus, and from those of freshwater catfishes. The morphological differences are discussed with respect to species–specific behavioural activities.
Structure and Innervation of the Inner Ear Sensory Organs in an Otophysine Fish, the Upside–down Catfish (Synodontis nigriventrisDavid)
Authors: Jensen Jan Chr.
Published: April 2010

All the sensory epithelia of the inner ear in the upside–down catfish (Synodontis nigriventrisDavid) were examined by light microscopy. The morphology of the membranous labyrinth and the orientation of the hair cells is similar to what has been found in other otophysine fishes. The sensory cells are of variable size both inter– and intraepithelially; particularly the macula sacculi is equipped with heterogeneous receptors. Regional differences in the hair cell density are presented for all the otolith organs plus the papilla neglecta. Nerve stainings reveal regional differentiation. The central areas are innervated by stout and stubbly nerve endings intermingled with a few thin nerve fibres while the peripheral parts are reached exclusively by thin axons. In the anterior region of the macula sacculi are found unique cup–shaped axon terminations which surround the basal parts of a single or a few sensory cells. The number and diameter range of the myelinated nerve fibres as well as the hair cell/axon ratio are presented. Electron microscopy demonstrates the presence of unmyelinated axons in all inner ear nerve ramuli.
Structure of the Testes, Spermatozoa and Spermatozeugmata of Mimagoniates barberiRegan, 1907 (Teleostei: Characidae), an Internally Fertilizing, Oviparous Fish
Authors: Pecio A. , Rafiński J.
Published: April 2010

Abstract The testis of Mimagoniates barberiis bipartite. Spermatogenic tissue is restricted to the anterior part. The posterior part of the testis is devoid of spermatogenic tissue and contains numerous efferent ducts filled with mature sperm. Cells in germinal cysts develop synchronously, sperm nuclei and flagella become oriented parallel in the late stages of spermiogenesis. In the caudal portion of the aspermatogenic part all sperms are arranged into unencapsulated sperm bundles — spermatozeugmata. Two types of spermatozeugmata are found both in the caudal portion of the testis and in milt. In the larger, spindle–shaped type, sperm flagella form the spindle tips. In the smaller ones, which have approximately a length of spermatozoon, the sperm are parallel and approximately in register. In both types sperm heads are arranged parallel. A mature spermatozoon is flail–shaped. The sperm head is highly elongated and situated alongside the flagellum, the tip of the head is directed backwards. Large mitochondria are situated on one side of the elongated nucleus only and form the tip of the head. Live spermatozoa move with the centriolar part ahead. Both testis and spermatozoon structure as well as formation of spermatozeugmata in M. barberiare highly derived features which perhaps evolved as adaptations to internal fertilization.
A New Type of Manchette Structure in Spermatids of Culex tigripes(Culicidae)
Authors: Ndiaye Mady , Mattei Xavier , Siau Yves
Published: April 2010

Abstract In young spermatids of Culex tigripes, microtubules organize a manchette which surrounds the nucleus. When the nucleus elongates, 1–5 expansions appear on the wall of the microtubules. They grow and branch out while the nucleus elongates and chromatin condenses. Expansions are straight or curved in shape. They have the same thickness as the microtubule walls, but they rarely constitute links between microtubules. The manchette disappears naturally at the end of spermiogenesis. The action of colchicine on spermatids leads to the complete disappearance of the microtubules and expansions, and inhibits the lengthening of the nucleus.
Coronary Artery Anatomy and Elasmobranch Phylogeny
Authors: Muñoz‐Chápuli R. , De Andrés A. V. , Dingerkus G.
Published: April 2010

Abstract The anatomical arrangements of the coronary arteries were compared in 36 species from eight orders of elasmobranchs and one species of holocephalians. Two main patterns of the coronary trunks are defined in the conus arteriosus. A dorsal and a ventral coronary trunk are present in lamnoid and carcharhinoid representatives (except in scyliorhinids), while two lateral coronary trunks are always observed in the holocephalian, hexanchoid, squaloid, squatinoid, scyliorhinid and batoid representatives. Posterior coronary arteries arising from subclavian branches are recorded only in rajoid and myliobatoid specimens. We propose that both the dorsoventral coronary trunk pattern and the presence of posterior coronary arteries are apomorphic. Thus, the phylogenetic analysis of these character–states supports the view that lamnoids are the sister–group of advanced carcharhinoids (carcharhinids and sphyrnids), sharing the dorsoventral coronary trunk pattern as a synapomorphy.
Immunocytochemical Distribution of 5‐HT (Serotonin) in the Nervous System of the Gastrotrich Turbanella cornuta
Authors: Joffe Boris I. , Wikgren Marianne
Published: April 2010

The 5‐HT (serotonin) distribution in the nervous system of the macrodasyoid gastrotrich Turbanella cornuta was studied using immunocytochemical methods. Positive immunoreaction was found in two pairs of neurons. The neurons of one pair had processes which extended peripherally to the surface of the body. Central processes of both pairs entered the brain commissure and proceeded into the longitudinal cords. Unlike other acoelomate worms studied so far, the Platyhelminthes and the Nematoda, in this gastrotrich no 5‐HT positive perikarya or processes were present in the pharynx innervation, and no positive neurons sent processes directly to the nerve cords
Occurrence and Ultrastructure of Collar Cells in the Stomach Gastrodermis of Polypodium hydriforme Ussov (Cnidaria)
Authors: Raikova Ekaterina V.
Published: April 2010

The existence of collar cells lining the stomach gastrodermis in free‐living Polypodium hydriforme and their ultrastructure are described. The collar cells are provided with a collar consisting of 9–10 microvilli which encircles a central flagellum and forms a flagellar pit. At the bottom of the pit around the basal part of the flagellum there is fine crystalline material which extends also in the spaces between the microvilli and keeps them straight. The flagellum has a typical axoneme (9+2), its basal body is located below the apical surface of the collar cell and continues into a striated rootlet. An accessory centriole is situated close to the upper part of the rootlet. The cell nucleus is located in the basal part of the cell. Prominent mitochondria with tubular cristae, Golgi cisternae and fragments of rough endoplasmic reticulum are situated mostly in the basal part of the cytoplasm. Discoidal vesicles are abundant in the apical cytoplasm. The collar cells are connected to each other by septate junctions and interdigitations. The ultrastructure of collar cells described here is discussed in comparison to that of other Cnidarians and in connection with the problem of Polypodium's systematic position.
Ultrastructure of Spermatozoa of the Yellow‐rumped Elephant Shrew Rhynchocyon chrysopygus (Mammalia: Macroscelidea) and the Phylogeny of Elephant Shrews
Authors: Woodall Peter F. , FitzGibbon Clare
Published: April 2010

The spermatozoa of the yellow‐rumped elephant shrew Rhynchocyon chrysopygus have a spatulate head, tapering to a rounded proximal end with a marked narrowing at the equatorial segment. There is a short pointed subacrosome and about 24 gyres of mitochondria were found in the midpiece. The coarse fibres surrounding the axonome show enlargement of numbers 1, 5, 6 and 9. The spermatozoa of all genera of elephant shrews have now been described allowing comparisons among them. R. chrysopygus has the shortest spermatozoon and the fewest number of gyres. The pointed subacrosome is considered an ancestral feature and is shared with Macroscelides. The enlargement of coarse fibres 1, 5, 6 and 9 is found in several groups including members of the archonta and paenungulates, both postulated as being related to elephant shrews.
Microscopical Anatomy of the Cyrtocrinid Cyathidium meteorensis (sive foresti) (Echinodermata, Crinoidea)
Authors: Heinzeller Thomas , Fechter Hubert
Published: April 2010

Light microscopy and scanning electron microscopy of three specimens of Cyathidium meteorensis (order Cyrtocrinida) revealed some special morphological features. The brachial articulation is provided with a long tendon at the aboral side; the entire articulation surface, including the areas where ligaments attach is built up by labyrinthic stereom. The calycinal ossicle lacks any internal vestiges of a pentameric composition; vertical planes with changing stereom direction lie irrespectively of radial or interradial planes. Gut, ovary and testis are histologically inconspicuous, and the location of the gonads inside the calyx is quite unusual. Both sexes develop outer gonoducts which probably are functionally adapted madreporic canals. The coelomic system differs from that of other crinoids in that a chambered organ is completely lacking. Simultaneously, the aboral nervous subsystem has no aboral nerve centre and simply terminates aborally in the ring‐shaped commissure. A glandular axial organ is absent, as are typical sacculi. The data are in accordance with two proposals made previously for Holopus rangii, viz., that the animals can feed raptorially, and that cyrtocrinids probably have evolved by loss of aboral calycinal ossicles of ancestors. In part, our observations differ from those in Cyathidium foresti, so we have chosen to use the species name meteorensis which has been considered a synonym of foresti.
Further Ultrastructural Studies on the Encapsulated Larva of Kronborgia isopodicola (Platyhelminthes, Fecampiidae), with Particular Reference to Nuclei
Authors: Williams J. B.
Published: April 2010

During development of the encapsulated Kronborgia isopodicola larva, nuclei of the body tissues and differentiating eyes undergo a continuous condensation, the progression of which is described. The brain is composed of a central neuropil and an outer layer of nerve cell perikarya. Neurosecretory cells are located at the sides of the brain. Some neurosecretory cell extensions are interposed between the cerebral neuropil and nerve cell perikarya; others overlie the photoreceptor cell processes of the eyes. The advanced encapsulated larva possesses a frontal complex, consisting of modified epidermis, secretory cells, gland ducts and nerve cell processes. The advanced larva is transparent and diminished in size, advantages possibly due in part to the extraordinary process of comprehensive nuclear condensation during ontogeny. The larva has a uniform epidermal ciliation and, while sharing certain features with trochophore larvae, is not of the trochophore type.