bluuebunny/crossref_metadata_2025_split huggingface dataset:
The behavior of pharyngeal outer epithelial cells during regeneration of the planarian Dugesia japonica japonica
Authors: Asai Etsuo 
Published: February 2005

AbstractThe behavior of the nuclei of pharyngeal outer epithelial cells was observed by electron microscopy during regeneration of head fragments of planaria transected at the prepharyngeal region. On the fourth day of regeneration, the surface cells of the pharyngeal rudiment show some evidence of differentiation: septate desmosomes and immature rod‐shaped bodies. These cells then develop many cilia and a few microvilli on their free surfaces, and the electron‐density of their karyoplasm and cytoplasm increases. The basal cytoplasmic processes of the surface cells protrude into the intercellular spaces between underlying cells. Each elongated nucleus goes down into one of these processes. Two types of nuclear descent are observed. The first type occurs when the basal lamina has not yet formed under the epithelial cells. The second type occurs when the basal lamina has already developed under the epithelial cells. Many microtubules are seen running along the long axis of the cells with descending nuclei. Fine fibrous bodies are frequently observed in the descending nuclei of the epithelial cells. Intercellular substances with moderate electron‐density are observed sporadically in the spaces between descending cytoplasmic processes and surrounding cells. Glycogen granules accumulate in large numbers in the basal cytoplasm in the vicinity of the descended nucleus. The mechanism of the descent of the perikarya of the pharyngeal outer epithelial cells is discussed in terms of these results.
Interfiber tension transmission in series‐fibered muscles of the cat hindlimb
Authors: Trotter John A. 
Published: February 2005

AbstractSeveral muscles of the cat hindlimb, including biceps femoris and tenuissimus, are composed of short, in‐series muscle fibers with tapered intrafascicular terminations. Tension generation and transmission within such muscles requires that active fibers should be mechanically coupled in series via myomyous junctions, specialized connective tissue attachments, or the endomysium. This report establishes that the tapered fibers of the cat biceps femoris and tenuissimus muscles have insignificant numbers of either myomyous or specialized connective tissue junctions. Tension appears to be transmitted in a distributed manner across the plasmalemma of the tapered (and probably the non‐tapered) portions of the fibers to the connective tissue of the endomysium, which is therefore an essential series elastic element in these muscles. Subplasmalemmal dense plaques were identified and may play a role in transmembrane force transmission. In addition to the endomysium, passive muscle fibers may also serve to transmit tension between active fibers, and therefore should also be considered to be series elastic elements.
Electron microscopic study of the development of amphioxus, Branchiostoma belcheri tsingtauense: The gastrula
Authors: Hirakow R. , Kajita N. 
Published: February 2005

AbstractThe gastrulae of amphioxus were investigated by means of scanning and transmission electron microscopy (SEM and TEM) during 7 arbitrary stages that were seen about 4 to 10 hr after fertilization. Throughout gastrulation, SEM revealed subtle differences in cells of the blastoporal lip. In fractured specimens at early and middle stages, two opposing zones different in shape, size, and connection of the component cells were found: one which consists of columnar smaller cells in close contact in animal region and the other which is composed of round or polygonal larger cells in looser association in vegetal region. The polar body was found unexpectedly on the concave vegetal surface of the early gastrula in about 25% of cases. This might be the result of migration of the polar body. A short cilium that later elongated was recognized on each cell at mid‐gastrula stage. The cilia on the dorsal surface (the neural ectoderm) of the final‐stage gastrula became shorter than those on the epidermal ectoderm. TEM of thin sections demonstrated that the cytoplasmic components of gastrula cells are essentially the same as those of cleavage cells. But, the homogeneous nucleus seen during cleavage changed into a heterogeneous structure in which a nucleolus and dense particles were seen. Until the late stage, regional characteristics of the gastrulae indicating definitively the anterior‐posterior and dorso‐ventral polarity were not detected in the present SEM and TEM study.
Ultrastructure of the agranular cells in the adenohypophysis of the South American lungfish, Lepidosiren paradoxa
Authors: Chiba Akira , Oka Shunya , Honma Yoshiharu , Ishiyama Mikio 
Published: February 2005

AbstractLight and electron microscopic examination demonstrated two types of non‐endocrine agranular cells, cavity boundary cells and stellate cells, in the adenohypophysis of the South American lungfish, Lepidosiren paradoxa. The cavity boundary cells line the hypophyseal cleft and diverticulum and display few microvilli, occasional cilia, prominent junctional complexes, and many cytoplasmic microfilaments. The stellate cells are scattered in the glandular parenchyma and are devoid of microvilli and cilia. When adjacent, they are connected to one another by desmosomes. Pinocytotic vesicles or caveolae are frequently seen along the plasma membrane of the agranular cells adjoining the endocrine cells or abutting on the basement membrane. Possible roles of the agranular cells, physically and metabolically supportive functions, are discussed on the basis of their ultrastractural features.
Orbital gland structure and secretions in the Atlantic bottlenose dolphin (Tursiops truncatus)
Authors: Tarpley Raymond J. , Ridgway Sam H. 
Published: February 2005

AbstractOrbital gland structure of the Atlantic bottlenose dolphin, Tursiops truncatus, was examined at the macroscopic, light microscopic, and electron microscopic levels. The gland completely encircles the ocular globe in a belt‐like fashion near the conjunctival fornix but is considerably more developed medially. Duct openings are scattered throughout the fornix and over the surface of the palpebral conjunctiva. Microscopically, the gland has a tubuloalveolar arrangement; alveolar cells contain numerous secretory vesicles which can be interpreted as two structural types by light and electron microscopy. Histochemical staining demonstrates that both types contain glycosaminoglycans. Lipid analysis of the glandular secretion (dolphin tears) shows them to be non‐oily and to contain only negligible amounts of cholesterol, triglycerides, phospholipids, and free fatty acids. The secretion is clear, slippery, and viscoelastic and well‐adapted to protecting the eye and to reducing frictional forces between the eye surface and surrounding seawater.
Fine structure of the spermatophores and their ejaculated forms, sperm reservoirs, of the Japanese common squid, Todarodes pacificus
Authors: Takahama Hideki , Kinoshita Tsutomu , Sato Michio , Sasaki Fumie 
Published: February 2005

AbstractSpermatophores in a squid, Todarodes pacificus, were observed by light and electron microscopy and were further analyzed by X‐ray microanalysis (XMA) of frozen thin sections. Each spermatophore consists of a sperm mass, a cement body, an ejaculatory apparatus, and some fluid materials, all of which are covered by an outer tunic. The outer tunic consists of about 20 membranous layers, each containing straight, parallel microgrooves. Each layer's microgroove pattern is roughly in an orthogonal arrangement with respect to the next layer's pattern. The sperm mass, which is the only cellular component, consists of a sperm rope which is coiled more than 500 times. Most of the spermatozoa in the rope are arranged regularly and are enveloped in materials which are well‐stained by Alcian blue. The cement body is located between the sperm mass and ejaculatory apparatus and has a hard outer shell with an arrowhead‐like structure, presumably for penetration into the tissue of the female. Calcium and phosphorus are present in the shell of the cement body, which also has an affinity for alizarin red. The ejaculatory apparatus consists of two tubes, designated as the inner tunic and the inner membrane.After the spermatophoric reaction, a sperm reservoir is formed at the anterior end of the extruded and inverted ejaculatory apparatus. The sperm reservoir, which encases the sperm mass, is composed of the cement body at the anterior end and the inner tunic of the ejaculatory apparatus at the posterior end.
Comparative anatomy and phylogeny of the cloacae of salamanders (Amphibia: Caudata). II. Cryptobranchidae, Hynobiidae, and Sirenidae
Authors: Sever David M. 
Published: February 2005

AbstractCloacae were examined from salamanders representing the three families in which fertilization of eggs is known or inferred to occur externally. The cloacae of male and female sirenids are aglandular and lack cilia. Sexual dimorphism in sirenid cloacae occurs only in the extent of epithelial stratification in the cloacal chamber in females (entire chamber) versus males (posterior angle of the vent). Both male and female Cryptobranchus alleganiensis possess ventral glands that secrete an acid mucopolysaccharide and have ciliated cloacal linings. The ventral glands are more numerous and hypertrophied in breeding male than female C. alleganiensis, but in males, ventral glands secrete only onto the surface of the cloacal lips along the anterior three‐fifths of the cloacal orifice, whereas in females, the glands secrete onto the border of the entire cloacal orifice. Except for male Onychodactylus japonicus, male and female hynobiids also possess only ventral glands and have ciliated cloacal linings. Hynobiid ventral glands secrete a glycoprotein. Much variation occurs, however, among these hynobiids in cloacal conformation, extent of epidermis into the cloaca, and anatomy of the ventral gland. Male O. japonicus possess an unciliated cloaca in which three types of cloacal glands occur, each giving unique reactions to tests for carbohydrates and proteins. The glands in male O. japonicus do not seem to be homologous to those found in spermatophore producing salamanders in the Salamandroidea, but this does not negate the possibility that O. japonicus makes spermatophores. Examination of cloacal characters in additional species of hynobiids may be useful in resolving intrafamilial phylogenetic relationships.
Collagen type conservation during metamorphic repatterning of the dermal fibers in salamanders
Authors: Frolich Larry M. , Schmid Thomas M. 
Published: February 2005

AbstractThe orientation of the fibers in the dermis of the tiger salamander, Ambystoma tigrinum, undergoes a dramatic repatterning at metamorphosis. The pre‐metamorphic, larval dermis is a tight layer composed of crossed fibers that wind helically around the trunk. This condition is retained by neotenic adults which do not undergo metamorphosis. In contrast, the metamorphosed adult dermis consists of a superficial, loose network of fibers invested with large multicellular glands—‐the stratum spongiosum—and a deeper tight layer of fibers—the stratum densum. However, unlike the crossed fibers of the pre‐metamorphic dermis, there is no preferred orientation to the fibers in either layer of the post‐metamorphic dermis.In order to evaluate whether these two distinctly different fiber patterns are constructed from biochemically similar fibers, the collagen types present in the pre‐ and post‐metamorphic dermis were determined using SDS‐polyacrylamide gel electrophoresis. Type I collagen is the predominant collagen of the dermis and the same major collagen types are present for all individuals, whether preor post‐metamorphic. Thus, the major types of collagen that compose the dermal fibers do not change during metamorphic repatterning of the dermis.
Three‐dimensional architecture of identified cerebral neurosecretory cells in an insect
Authors: Westbrook Anne L. , Haire Mary E. , Kier William M. , Bollenbacher Walter E. 
Published: February 2005

AbstractThe organization of identified neurosecretory cell groups in the larval brain of the tobacco hornworm, Manduca sexta, was investigated immunocytologically. Computer‐assisted three‐dimensional reconstruction was used to examine the architecture of the neurosecretory cell groups. The group III lateral neurosecretory cells (L‐NSC III) which produce the prothoracicotropic hormone are located dorsolaterally in the protocerebrum and extend axons medially that decussate to the contralateral lobe prior to exiting the brain through the nervi corporis cardiaci I + II. The group IIa2 medial neurosecretory cells (M‐NSC IIa2) are located anteriorly in the medial dorsal protocerebrum. The axons of these cells also exit the brain via the contralateral nervi corporis cardiaci I + II. However, their axons traverse a different pathway through the brain from that of the L‐NSC III axons. Each of the cell groups possesses elaborate dendrites with terminal varicosities. The dendrites can be classified into specific fields based upon their location and projection pattern within the brain. The dendrites for these two neurosecretory cell groups overlap in specific regions of the protocerebral neuropil. After the axons of these neurosecretory cells exit the brain through the retrocerebral nerve, they innervate the corpus allatum where they arborize to form neurohemal terminals in strikingly different patterns. The L‐NSC III penetrate throughout the glandular structure and the M‐NSC IIa2 terminals are restricted to the external sheath. A third group of cerebral neurosecretory cells, the ventromedial neurons (VM) which stain with the monoclonal antibody to prothoracicotropic hormone in Manduca, are located anteriorly in the medial region of the brain. The axons of these cells do not exit the brain to the retrocerebral complex, but rather pass through the circumesophageal connectives and ventral nerve cord. These neurons appear to be the same VM neurons that produce eclosion hormone. One dendritic field of the L‐NSC III terminates in close apposition to the VM neurons. The distinct morphologies of these neurosecretory cell groups in relation to other cell groups and the distribution of neuropeptides within the neurons suggest that insect neurosecretory cells, like their vertebrate counterparts, may have multiple regulatory roles.
Variation in venous drainage of the pectoral fins of batoids (subclass elasmobranchii: Superorder batoidea)
Authors: Alexander R. L. 
Published: February 2005

AbstractA contrast radiographic study of pectoral fin venous drainage in rays shows it to be morphologically conservative across the batoids studied. In all species examined, ventral propterygial and mesopterygial veins drain the anterior and posterior lobes of the fin, respectively. Variation in the central connections of these vessels enables the identification of four major patterns of drainage. A fifth pattern consists of additional veins that drain the central region of the fin between the zones drained by the pro‐ and mesopterygial veins. There is a significant, positive association between the numbers of brachial veins present and the dimensions (in numbers of radial cartilages) of the central, basal region of the fin. There is also an association between the types of patterns present and the dimensions of the propterygial and metapterygial basal cartilages.
Testis and epididymis of the indian wall lizard (Hemidactylus flaviviridis): Effects of flutamide on FSH and testosterone influenced spermatogenesis, Leydig Cell, and Epididymis
Authors: Rai Umesh , Haider Shamim 
Published: February 2005

AbstractTo determine the separate spermatogenic actions of FSH and testosterone, adult male lizards Hemidactylus flaviviridis with recrudescent testes were administered the non‐steroidal antiandrogen flutamide either alone or in combination with FSH or testosterone, and the histology and histochemistry of the testes and ductus epididymides were studied. Flutamide‐treated animals displayed a marked hypertrophy of Leydig cells. A few spermatids were also seen in testis of more than half the animals treated with flutamide. Flutamide also produced a significant increase of primary spermatocytes; no spermatids were observed in controls. A significant inhibition of spermatogenesis was noted in lizards treated either with testosterone alone or in combination with flutamide. Ovine FSH treatment caused a significant stimulation of spermatogenesis, as indicated by the increase of primary and secondary spermatocytes and the transformation of secondary spermatocytes into spermatids or, in a few cases, into spermatozoa. A considerable depletion of sudanophilic lipid and moderate Δ5‐3β‐hydroxysteroid dehydrogenase activity was noted in the Leydig cells of FSH‐treated animals indicating enhanced steroidogenesis. Similar results were obtained when lizards were treated with flutamide + FSH. The effects of simultaneous treatment of flutamide with FSH or testosterone on ductus epididymidis revealed that flutamide markedly inhibited the epithelial cell height and lumen diameter with a loss of luminal content when compared to FSH or testosterone‐treated lizards.
The gill arch of the striped bass (Morone saxatilis). IV. Alterations in the ultrastructure of chloride cell apical crypts and chloride efflux following exposure to seawater
Authors: King Judy A. C. , Hossler Fred E. 
Published: February 2005

AbstractOsmotically induced alterations in the ultrastructure of the apical crypts of chloride cells and changes in chloride efflux were studied in striped bass (Morone saxatilis). Striped bass were divided into three groups: fish adapted to freshwater, fish transferred directly from freshwater to 100% seawater (3% salt, w/v) for 24 hr or less, and fish adapted to 100% seawater for 7 days or more. Transmission electron microscopy studies revealed multicellular complexes of cells in both freshwater‐ and seawater‐adapted fish. Cytoplasmic indigitations between cells in the complex were more numerous in seawateradapted bass. Scanning electron microscopy studies showed that the apical extensions in freshwater fish were uniform in size. Changes in ultrastructure and chloride efflux were observed within 3 hr after transfer to seawater. Initially the apical extensions of chloride cells become longer, more prominent, and branched. After 7 days in seawater some of the apical crypts develop into a deeper “pit” structure, while others remain like those of freshwater fish. An increase in the number of apical crypts is measured by 14 days after transfer. Chloride efflux increases to five times freshwater values after 24 hr and 17 times freshwater values after 7 days in seawater. Mitochondrial density is not significantly different between freshwater and seawater fish (7 or more days). The response of chloride cell apical crypts is not an all‐or‐none phenomenon as observed in other species. Striped bass are able to increase chloride efflux when osmotically stressed with little ultrastructural alteration.
Structure of the adult female reproductive system and oogenetic mode in the sea spider, Endeis nodosa (Pycnogonida; Endeidae)
Authors: Miyazaki Katsumi , Makioka Toshiki 
Published: February 2005

AbstractAs in other pycnogonids, the adult female reproductive system of Endeis nodosa is limited to the trunk and walking legs of the cephalothorax. The U‐shaped trunk ovary extends eight blind branches separately into the corresponding walking legs up to each femoral segment. In both the trunk and pedal region, the ovary lies dorsally above the gut, sandwiched between the dorsal and the ventral layer of the horizontal septum. Oogonia and very young oocytes occur throughout the ovary. They fill the trunk ovary and, in the tubular pedal ovary, are aggregated into several cord‐shaped longitudinally arranged germ zones. More advanced oocytes occur only in the pedal ovary. None lie in the germ zones. but instead they protrude individually from the wall of the pedal ovary into the hemocoel on cellular stalks. Vitellogenesis occurs in the larger stalked oocytes. An oval genital pore with a cuticular lid lies on the ventral surface of the second coxa of each walking leg. The pedal ovarian lumen is directly connected to the genital pore by a short oviduct in the second coxa. The ovarian structure and oogenetic modes in this pycnogonid species show some common characteristics with those of most chelicerates.
Cytology and function of the madreporite systems of the starfish Henricia Sanguinolenta and Asterias Vulgaris
Authors: Ferguson John C. , Walker Charles W. 
Published: February 2005

AbstractThe madreporite regions of two species of starfish were examined by high‐resolution light microscopy and transmission electron microscopy. In both, the madreporite gutter epithelium is predominantly composed of ciliated cells, each bearing a single elongate cilium and numerous microvilli that support and are embedded in cuticle. Fine, contractile pores (10–12 μm) open from the gutters into canals that descend mainly to the underlying ampulla and stone canal. Cells at the pore openings lack cuticle, have rounded, sometimes protruding apices, and bear intermeshing cilia that extend outward through the pores. Below them, the pore canal is lined with irregular, granule‐containing ciliated cells possessing retractable apical head pieces and secretory cells containing clusters of unstainable vesicles. Above the basal lamina here and elsewhere is a well‐developed nerve plexus. Where the pore canals open into the ampulla and connecting axial sinus, the ciliated cells are more cuboidal, vesiculated secretory cells are absent, and free coelomocytes are numerous. The stone canal is lined with tall, densely packed ciliated cells with numerous microvilli and long iuminal extensions. Cells on its central ridge tend to form choanocyte‐like collars. The stone canal appears to be a strong ciliary pump that draws fluid from the axial sinus and madreporite pores. It is likely that the complex form of the madreporite gutters and pore canals provides multiple levels of coordinated defense against the entry of undesirable materials, and probably satisfaction of much of the nutritional needs of the parts from incoming and recirculated fluid.
Ultrastructure of the nephron of the young camel Camelus dromedarius
Authors: Safer A. M. , Abo‐Salem K. S. 
Published: February 2005

AbstractThe present study was undertaken to compare the ultrastructure of the kidney of young camels (Camelus dromedarius) with that of adult kidneys, described previously (Safer et al., '88). Young kidneys are known to produce a urine that is only about half as concentrated as that of adult kidneys (Maloiy, '72; Abo‐Salem, '88). While possessing most of the ultrastructural features of adult kidneys, and of mammalian kidneys in general, young kidneys differ from those of adults in several respects. The basal lamina comprising part of the filtration barrier is approximately one‐fourth as thick as that of the adult kidney. Young kidneys also lack thickened, heterogeneous basal laminae associated with the parietal layer of Bowman's capsule, proximal convoluted tubules, and the thin segments of the loops of Henle in adult kidneys. In addition, the proximal convoluted tubules of young kidneys contain mixtures of lightly stained and darkly stained cells, while those of adult kidneys possess only lightly stained cells. These differences between young and adult kidneys might in part be related to a greater degree of water deprivation experienced by adult animals.