bluuebunny/crossref_metadata_2025_split huggingface dataset:
A morphological study of the nervous system of the praesoma of Octospinifer macilentus (Acanthocephala: Noechinorhynchidae)
Authors: Gee Randall J. 
Published: February 2005

AbstractThe nerve pathways in the praesoma are described for the first time for a member of the genus Octospinifer. Eleven nerves, five paired, and one single, are traced from the cerebral ganglion to their associations with the musculature of the body wall, neck sense organs, and the musculature of the proboscis wall and the invertor muscles of the proboscis. The structure and location of the Stützzelle (support cell) and its association with the neck sense organs are described. A comparison with the nervous system in the praesoma of Noechinorhynchus and Paulisentis is discussed.
Quantitative electromyography of the masticatory muscles of Pteropus giganteus (Megachiroptera)
Authors: De Gueldre Greet , De Vree Frits 
Published: February 2005

AbstractMastication has been studied by cinematography and quantitative electromyography while flying foxes, Pteropus giganteus, were freely feeding on standardized pieces of apple, soaked raisin, and banana.The primarily orthal mandibular movements are caused by mainly bilaterally symmetrical firing of all the masticatory muscles. Asymmetric activity in the superficial and deep masseter and medial pterygoid causes slight protrusion early in opening. Slight lateral deviations at the end of opening and at the start of closing are caused by asymmetric and asynchronous activity in the pterygoids and digastrics, and by asynchronous firing of the deep temporalis and zygomaticomandibularis. Food consistency affects movement characteristics as well as characteristics of muscular activity.In this study electromyograms were digitized and the number of spikes and mean amplitude per interval (set by the filming rate) recorded. Although a significant correlation exists between these descriptors, the product thereof appears to be the best predictor of certain kinematic variables (cycle length and maximum excursion of the mandible). On the other hand, the changes in magnitude of muscular activity as a function of the position of a cycle in the reduction sequence and as a function of food consistency are more translated in a variation of the mean amplitude than in a variation of the number of spikes per interval. Observed variation differs among muscles studied. It is most apparent in the superficial and deep masseter and least in the temporalis and zygomaticomandibularis.Late cycles of apple and raisin mastication are long and exhibit large gapes but almost no anterior movement. The adductor activity frequently shows a synchronized, pulsatile pattern leading to an unfused tetanus.
The cephalic vascular anatomy of three species of sea snakes
Authors: Young Bruce A. 
Published: February 2005

AbstractThe primary and secondary elements of the cephalic vascular system in some sea snakes are similar to those of the generalized ophidian pattern. The three species examined in this study revealed only minor variations in vascular morphology; these variations appear to be correlated with myological differences among the three species. For example, in Hydrophis melanocephalus it appears that the depressor mandibulae artery is displaced by the cranially expanded insertion of the semi‐spinalis and spinalis muscles. A preliminary hypothesis is put forth that explains the apparent constancy of the cephalic vascular system of ophidians in terms of possible constraints due to cranial kinesis.
Ultrastructure of the anterior salivary gland cells of the giant leech, Haementeria ghilianii (Annelida, Hirudinea)
Authors: Walz Bernd , Schäffner Karl‐Heinz , Sawyer Roy T. 
Published: February 2005

AbstractThe giant anterior salivary gland cells from the large mammalian blood‐sucking, glossiphoniid leech, Haementeria ghilianii, can be subdivided into three morphologically and functionally distinct regions: (1) a soma, responsible for the synthesis and storage of secretory products; (2) a long cell process, responsible for the storage and intracellular transport of the secretory vesicles; and (3) the site of exocytosis at the process terminal. The giant somata are densely packed with secretory vesicles. Deep plasmalemmal invaginations invade the soma and form an extensive system of extracellular lacunae. The rough endoplasmic reticulum (ER) and the Golgi apparatus are organized in the cell periphery, near the highly branched nucleus, and along the lacunae. The somata taper into long processes extending over several centimeters to the proboscis tip. These contain secretory vesicles through their whole length. In the process periphery, the vesicles are completely ensheathed by a concentric subplasmalemmal smooth ER cisterna. This originates deeply within the soma and extends through the whole cell process to its terminal. The ER provides support for up to several hundred longitudinally oriented microtubules. Secretion occurs at the very tip of the cell processes, each of which terminates at the proboscis tip at the base of a cuticular pore.We found synapses close to the sites of exocytosis, providing morphological evidence for neuronal control of secretion.
Specialization in the diencephalon of advanced teleosts
Authors: Gómez‐Segade Pablo , Anadón Ramón 
Published: February 2005

AbstractCytoarchitectonic studies of the pretectum and diencephalon of five teleosts (Gaidropsarus mediterraneus, Syngnathus acus, Gasterosteus aculeatus, Pleuronectes platessa, and Coris julis) have shown the hypothalamus to be the most highly developed region in all five. The nucleus praeopticus magnocellularis is well developed in Coris and the euryhalines Gasterosteus and Pleuronectes; in Coris and Pleuronectes the nucleus lateralis tuberis is also prominent. Except in Gaidropsarus, however, the most striking area in the hypothalamus is the glomerulosus complex, with its voluminous nucleus glomerulosus. In Coris and Pleuronectes a glomerular offshoot of this nucleus in the dorsal thalamus is evidence of its being homologous with the nucleus anterior thalami of primitive teleosts. The nucleus diffusus is also very large in all except Gaidropsarus. In Coris and Syngnathus the saccus vasculosus exhibits a peduncle, and in Pleuronectes it invades the hypophysis. The descriptive analysis is complemented by measuring the relative size and cell density of the cell groups studied.A comparison among the five species studied shows that nuclei probably related to the olfactory system are more developed in Gaidropsarus and Pleuronectes, whereas the supposed visual nuclei are prominent in Coris, Gasterosteus, and Syngnathus but poorly developed in Gaidropsarus. In general, the findings of the present study, together with published results concerning Lizza (Gómez‐Segade and Anadón, Trab. Inst. Cajal Invest. Biol. 72:187–214, 1981), show that Coris has the most complex diencephalon among these species. Moreover, Gaidropsarus presents an organization very different from that of the other five species and probably represents a parallel evolutionary lineage.
Dense granule‐containing cells in arterial chemoreceptor areas of the tortoise (Testudo hermanni)
Authors: Kusakabe T. , Ishii K. , Ishii K. 
Published: February 2005

AbstractLight‐ and electron‐microscopic observations of the chemosensory areas of the arteries of the tortoise (Testudo hermanni) reveal that clusters of nonmuscular cells are found in the adventitial layer of restricted regions of the carotid artery, aortic arch, and pulmonary artery. In these clusters, three types of cells are complexly interwoven: the G‐cell closely resembles the glomus cell, which has been found in the arterial chemoreceptor area of several animal species; the LG‐cell has very large electron‐dense granules; the third type is a G‐ and LG‐cell supporting cell. Membrane specializations are often observed at apposing membranes between G‐cells. Two kinds of nerve endings synapse with G‐cells, one with numerous clear synaptic vesicles, the other without vesicles. Some G‐cells are in membrane‐to‐membrane contact with smooth‐muscle cells (g‐s connection), and here a membrane thickening is visible. Nerve terminals with numerous synaptic vesicles synapse with the LG‐cells. The G‐cell in the carotid artery, the aorta, and the pulmonary artery is a chemoreceptor element ultrastructurally the same as the glomus cell in the arterial chemoreceptor area of various vertebrate species.
Embryonic growth and trophotaenial development in goodeid fishes (Teleostei: Atheriniformes)
Authors: Lombardi Julian , Wourms John P. 
Published: February 2005

AbstractEmbryonic growth and trophotaenial development are examined in two species of goodeid fish, Ameca splendens and Goodea atripinnis. During gestation of A. splendens, embryonic dry mass may increase from 0.21 mg at the onset of development to 31.70 mg at term. In G. atripinnis, embryonic dry mass ranges from 0.25 mg at the onset of development to 3.15 mg at term. Increase in mass is primarily due to the uptake of maternally derived nutrients by trophotaeniae, externalized embryonic gut derivatives. Trophotaenial development in both species is divisible into five phases. During the first phase, the anus is formed. The second phase involves dilation of the anus, enlargement of the perianal lips, differentiation of the hindgut absorptive epithelium, and formation of the trophotaenial peduncle. The third phase is characterized by a further marked hypertrophy and lateral expansion of the perianal lips that results in the formation of short trophotaenial processes. During the fourth phase, there is continued outward expansion of the inner mucosal surface of the trophotaenial peduncle that results in its eversion and lobulation. Placental function is established by this phase. Axial elongation and dichotomous branching of trophotaenial processes occurs during the fifth phase. Development of rosette and ribbon trophotaeniae differ in the degree of axial elongation during the fifth and final phase.
The labral glands in Centropages typicus (Copepoda, Calanoida). II. Sites of secretory release
Authors: Arnaud Jean , Brunet Michel , Mazza Jacques 
Published: February 2005

AbstractTwo groups of external excretory pores associated with glandular units (AU and LPU) were observed on the labrum, one pair laterally and three pairs posteriorly. Each external pore leads to an underlying conical, flask‐shaped epidermal chamber. The wide base of this chamber is perforated by an internal pore that delivers secretions from the excretory duct of a glandular unit. The chambers serve to protect the internal pores from turbulence in the outside environment. Expulsion of secretions from the chambers is probably brought about by contraction of labral striated muscles, which synchronizes opening of the AU and LPU pores. A complex funnel‐shaped structure forms the internal end of the excretory duct between each chamber and the corresponding pole of accumulation for the secretory product of a glandular unit. This structure, composed of an epidermal syncytium lined by a sleeve of several aligned auxiliary cells, probably ensures a tight connection between the epidermal chamber and the syncytium. The dorsalmost glandular units (LDU) have no pores in the vicinity of their poles of accumulation. Instead they secrete through cuticular ducts delimited by aligned auxiliary cells. External pores for these canals have not yet been located. The secretions of lateral pores may be mucopolysaccharides that play an essential role in agglutination of food particles soon after capture, while the secretions of posterior pores may contain glycoproteins that mix with food only after ingestion into the buccal cavity and probably start the process of digestion.
Development of the Malpighian tubules in Cloeon dipterum (Ephemeroptera)
Authors: Nüesch Hans 
Published: February 2005

AbstractThe development of the Malpighian tubules is studied in Cloeon dipterum through all stages from the youngest larva to the adult. The Malpighian tubules are found to be outgrowths of the posterior part of the endodermal midgut and not of the ectodermal hindgut. In the adult the part of the intestine with the tubule openings becomes separated by an ingrowing fold of the epithelium from the anterior main part of the midgut that forms a large thin‐walled and air‐filled bladder. The characteristics of the developmental stages, which served to determine the age of the animals, are given.
Ultrastructure of the “pigment knob” ofPleuromammaspp. (Copepoda: Calanoida)
Authors: Blades‐Eckelbarger Pamela I. , Youngbluth Marsh J. 
Published: February 2005

AbstractThe calanoid copepod genusPleuromammais easily distinguished from all other copepods by the presence of a rounded, dark‐red cuticular structure ( = pigment knob) that protrudes from the left or right side of the second thoracic segment in both sexes. The present study of the pigment knob reveals a complex ultrastructure consisting of various cell types within three distinct areas that are bathed by hemolymph from the lateral sinus. The knob is covered by a greatly expanded cuticle through which a pore passes. The pore appears to connect with a centrally positioned pigment cell containing a large mass of darkly staining granules. This suggests that the knob may have a secretory function. Observations of live animals and dissected pigment knobs, however, indicates that the knob does not secrete a luminescent material nor does it luminesce internally.
Stages of oocyte development in the pipefish, Syngnathus scovelli
Authors: Begovac Paul C. , Wallace Robin A. 
Published: February 2005

AbstractOocyte development occurs in a temporal and spatial pattern in the ovary of the pipefish, Syngnathus scovelli. Cytological observations combined with [3H]thymidine uptake and cell culture were used as criteria to identify six stages of oocyte development in this species. Stage I—Oogonia, found within the germinal ridge. Stage II—Oocytes in primary growth, subdivided into (1) chromatin‐nucleolus oocytes in early prophase I of meiosis, also found within the germinal ridge, and (2) perinucleolar oocytes, which possess multiple nucleoli and are within definitive follicles (the Balbiani vitelline body is the main cytoplasmic component in these latter oocytes). Stage III—Oocytes distinguished by the appearance of cortical alveoli, the vitelline envelope, and lipid. Stage IV—Vitellogenic oocytes, which accumulate yolk proteins and possess primary, transitional, and mature yolk spheres. Stage V—Maturational oocytes, which are competent to undergo final meiotic maturation in vivo and in response to the steroid 17 α‐hydroxy‐20β‐dihydroprogesterone in vitro. Stage VI—Ovulated mature eggs, which are present in the ovary lumen and are capable of being fertilized. These studies provide a staging series for oogenesis and oocyte development in the pipefish and relate these stages to the unusual ovary in this animal.
Spermiogenesis in the bluegill (Lepomis macrochirus): A study of cytoplasmic events including cell volume changes and cytoplasmic elimination
Authors: Sprando R. L. , Russell L. D. 
Published: February 2005

AbstractThe process involved in the reduction of both nuclear and cytoplasmic volume was investigated in the bluegill (Lepomis macrochirus), a teleost fish. Young spermatids contained centrally positioned nuclei which, with time, moved toward the cell surface to become eccentrically positioned. Chromatin condensation was initiated from a region near the implantation fossa, whereas at the opposite pole of the nucleus an area sparse in heterochromatin (clear area) was noted. The nuclear membrane lying adjacent to the clear area dissolved and subsequently reformed, yielding a nucleus with a reduced volume. During this process, packets of cytoplasm surrounded by a double membrane were formed along the future midpiece. The packets of cytoplasm migrated toward the cell surface, protruded from the surface, and were extruded into the spermatocyst lumen. These structures, termed residual bodies, were subsequently endocytosed, accumulated into large phagocytic vocuoles, and eventually degraded by the nearby Sertoli cell. When the spermatocyst ruptured, spermatozoa containing sparse cytoplasm were released into the excurrent duct system. During spermiogenesis, both the nuclear and cytoplasmic volumes decreased substantially (80%, 92% respectively) leading to an overall 87% reduction in total cell volume.
Spermatogenesis in the salps Thalia democratica and Cyclosalpa affinis (Tunicata: Thaliacea): An electron microscopic study
Authors: Holland Linda Z. 
Published: February 2005

AbstractThe fine structure of the male germinal cells in testes of two salps, Thalia democratica and Cyclosalpa affinis, is identical. The earliest germ cells seen were spermatocytes, located at the periphery of the testis and sometimes connected by cytoplasmic bridges. They are spherical with an anucleolate nucleus, a pair of centrioles, aboundant free ribosomes, sparse rough endoplasmic reticulum, and about five mitochondria. No Golgi complex was seen. The earliest spermatids, though similar to the spermatocytes, are smaller and have only one centriole. Spermatids develop (1) singly, (2) joined by cytoplasmic bridges, or (3) in syncytia. The next stage has a flagellum, a single large mitochondrion with dense material in some intracristal spaces, and a patch of highly condensed chromatin in the nucleus adjacent to the centriole. Subsequently the nucleus and the spermatid elongate. During elongation (1) the mitochondrion remains lateral to the nucleus and the amount of intracristal material enlarges, (2) the central core of condensed chromatin increases, and (3) the remainder of the chromatin becomes organized into dense strands. When elongation is 75% complete, the dense strands of chromatin appear to coalesce, to become homogeneous and denser than the core of chromatin, and the mitochondrion transforms into dense tubules. Finally, the mitochondrion wraps around the nucleus and extends its entire length, ultimately becoming a single tubule spiraled about 45 times around the nucleus. The mature sperm head is 18 μm long, tapering from 0.8 μm posteriorly to a tip about 0.14 μm wide. There is no acrosome. The single (distal) centriole of the sperm gives rise to a 9+2 flagellum with a fuzzy coat and dense material peripheral to each of the nine doublets. Spermiogenesis in T. democratica and C. affinis is similar to that in ascidians, and the sperm share many features with sperm of colonial ascidians in the suborder Didemnidae. The results, therefore, suggest that salps are closely related to ascidians and support the view that colonial ascidians gave rise to salps.
Fine structure of oocyte maturation in a crinoid echinoderm, Oxycomanthus japonicus: A time‐lapse study by serial biopsy
Authors: Holland Nicholas D. 
Published: February 2005

AbstractNatural maturation of the oocytes of Oxycomanthus japonicus can be predicte in advance, and the multiple ovaries permit unintrusive serial biopsies. Ovaries were fixed for transmission electron micrscopy at 15‐min intervals before, during, and after oocyte maturation. The start of maturation of each oocyte is signaled by the breakdown of the germinal vesicle and the disruption of a macula adhaerens associating the oocyte with nongerminal cells of the ovary. This disruption is followed by an ovulation of the oocyte into the ovarian lumen. Ovulation takes about 1 hr, and a continuous vitelline coat is produced around the oocyte during this interval. Within the oocyte cytoplasm, patches of nuage and the annulate lamellae disappear at 30 and 45 min after the start of oocyte maturation, respectively. Micropapillae become transiently abundant at the oocyte surface both at the time of germinal vesicle breakdown and around the time when the first and second polar bodies are produced. Oocyte maturation takes about 2 hr from start to finish, and the emission of the second polar body marks the beginning of the stage of the ovum. Within the cytoplasm of the ovum, the haploid chromosomes develop into chromosome‐containing vesicles, which later fuse into a single female pronucleus. Pronuclear ova are retained in the ovarian lumen for about 1 hr and are then spawned into the surrounding seawater, where fertilization takes place.
Morphology and ultrastructure of the sensory spine, a presumed mechanoreceptor of Sphaeroma hookeri (Crustacea, Isopoda), and remarks on similar spines in other peracarids
Authors: Brandt Angelika 
Published: February 2005

AbstractThe isopod Sphaeroma hookeri and many other isopods and peracarids have a sensory spine with laterally inserting sensory hair, positioned in the apical region of the propodal palm of pereopod 1. This spine is innervated by five to eight sensory cells (each giving rise to one cilium) the dendrites of which can be divided into an inner and outer dendritic segment. The cilia are surrounded by an extracellular, electron‐dense dendritic sheath. Thirteen enveloping cells are present. The outer dendritic segment (structure beyond the basal bodies) contains two receptor lymph cavities; the inner one lying within the dendritic sheath is homologous with the inner receptor lymph cavity of insects.Scolopales, or tubular bodies, are lacking; their function is probably accomplished by the dendritic sheath. Apically the sensory hair does not have a pore, and the spine is heavily sclerotized. The inner dendritic segment begins with a basal body from which rootlets of different length and thickness extend into the dendrite. In the latter is an accumulation of vesicles. The dendrites keep close contact with other dendrites and the enveloping cells by desmosomal membrane structures. The possible importance of the sensory spine for phylogenetic studies is discussed.
Spermiogenesis in the bullfrog (Rana catesbeiana): A study of cytoplasmic events including cell volume changes and cytoplasmic elimination
Authors: Sprando R. L. , Russell L. D. 
Published: February 2005

AbstractThe process by which spermatid cytoplasmic volume is reduced and cytoplasm eliminated during spermiogenesis was investigated in the bullfrog Rana catesbeiana. At early phases of spermiogenesis, newly formed, rounded spermatids were found within spermatocysts. As acrosomal development, nuclear elongation, and chromatin condensation occurred, spermatid nuclei became eccentric within the cell. A cytoplasmic lobe formed from the caudal spermatid head and flagellum and extended toward the seminiferous tubule lumen. The cytoplasmic lobe underwent progressive condensation whereby most of its cytoplasm became extremely electron dense and contrasted sharply with numerous electron‐translucent vesicles contained therein. At the completion of spermiogenesis, many spermatids with their highly condensed cytoplasm still attached were released from their Sertoli cell into the lumen of the seminiferous tubule. There was no evidence of the phagocytosis of residual bodies by Sertoli cells. Because spermatozoa are normally retained in the testis in winter and are not released until the following breeding season, sperm were induced to traverse the duct system with a single injection of hCG. Some spermatids remained attached to their cytoplasm during the sojourn through the testicular and kidney ducts; however, by the time the sperm reached the Wolffian duct, separation had occurred. The discarded cytoplasmic lobe (residual body) appeared to be degraded within the epithelium of the Wolffian duct. It was determined that the volume of the spermatid was reduced by 87% during spermiogenesis through a nuclear volume decrease of 76% and cytoplasmic volume decrease of 95.3%.