bluuebunny/crossref_metadata_2025 huggingface dataset:
Body mass and natural diet as determinants of the number and volume of adipocytes in eutherian mammals
Authors: Pond Caroline M. , Mattacks Christine A.
Published: February 2005

Total dissection of a randomly collected sample of 202 adult and subadult eutherian mammals, combined with site‐specific adipocyte volume determination, shows that the number of adipocytes in the body is proportional to (Body Mass)0.74 for predominantly carnivorous species and to (Body Mass)0.78 for mainly herbivorous, nonruminant mammals. Adipocyte expansion or shrinkage, not proliferation or depletion of adipocyte number, is the principal mechanism of adipose tissue enlargement and reduction. Therefore, the adipocytes of large mammals are larger than those of smaller specimens of similar dietary habits and fatness. We suggest that the presence of more numerous, smaller adipocytes in smaller mammals is related to their higher mass‐specific metabolic rate. The adipose tissue of mammals with a predominantly carnivorous diet contains 4.6 times as many adipocytes as that of herbivorous nonruminants of similar body mass; but nonruminant herbivores are not necessarily fatter because the adipocytes of carnivorous mammals are proportionately smaller than those of nonruminant herbivores. We suggest that a carbohydrate‐based energy metabolism is associated with fewer, relatively larger adipocytes and that when lipids and proteins form the major dietary energy source, adipose tissue consists of a greater number of smaller adipocytes.
Ultrastructure of the spermatozoon and spermiogenesis in the interstitial annelid Potamodrilus fluviatilis
Authors: Bunke Dieter
Published: February 2005

The ultrastructure of spermatozoa and its genesis (spermiogenesis) have been investigated in the interstitial annelid Potamodrilus fluviatilis. The mature spermatozoa are threadlike cells which are bent at the base of the flagellum, giving the cell a hairpinlike appearance. The acrosome consists of an unusual, long, flasklike vesicle with a granum in its basal part. The cylindrical nuclear region is characterized by a monolayer of vesicles enwrapping the posterior half of the nucleus. This region is endowed with a number of altered rodlike mitochondria. No middlepiece is present. The basal body of the flagellum is obliquely arranged with respect to the long axis, giving rise to a curved flagellum, which, along most of its length, exhibits a thick layer of vacuolized cytoplasm around the axoneme. During spermiogenesis, which occurs in the body fluid, spermatids develop at the surface of syncytial masses which have been formed during meiotic divisions. The acrosome protrudes in the distal part of the cell, while the basal body of the flagellum is shifted toward the proximal region, which connects the cell with the cytophore. These are unusual features in annelid spermiogenesis. As indicated in Discussion, the phylogenetic implications of these findings include the assumption that Potamodrilus is not related to any oligochaete or even any other clitellate group or species and, hence, has to be excluded from these taxa.
The musculature of squid arms and tentacles: Ultrastructural evidence for functional differences
Authors: Kier William M.
Published: February 2005

The transverse muscle mass of the arm and the transverse and circular muscle masses of the tentacle of squid (Loligo pealei and Illex illecebrosus) were examined by transmission electron microscopy. Previous work had indicated that although similar in gross arrangement, the transverse muscle mass of the tentacle creates rapid elongation during prey capture while the transverse muscle mass of the arm is involved in creating bending movements. The difference in function between the transverse muscle masses of the arms and tentacles is reflected in differences in ultrastructure. The transverse muscle mass of the arm is made up of regular, obliquely striated muscle fibers 1–6 μm in diameter. The transverse and associated circular muscle masses of the tentacle are made up of cross‐striated muscle fibers 1–3 μm in diameter. The cross‐striated muscle fibers have A bands approximately 0.5 μm (I. illecebrosus) and 0.9 μm (L. pealei) in length and a resting sarcomere length of 0.9 μm (I. illecebrosus) and 1.6 μm (L. pealei), suggesting a relatively high shortening speed for this muscle type. The cross‐striated cells are not divided up into myofibrils, and the sarcoplasmic reticulum is located beneath the sarcolemma. Vernier displacements of the sarcomeres were observed. The myofilaments of the obliquely striated muscle fibers of the arm surround a central core containing mitochondria and the cell nucleus. The sarcoplasmic reticulum of the obliquely striated cells is located beneath the sarcolemma, in the plane of the Z elements, and surrounding the mitochondrial core.
Gross and fine structure of the antennal circulatory organ in cockroaches (Blattodea, Insecta)
Authors: Pass Günther
Published: February 2005

The antennal circulatory organ ofPeriplaneta americanaandBlaberus craniiferwas investigated by light and electron microscopy. This organ consists of two pulsatile ampullae located near the antennal base which are interconnected by a large transverse muscle and associated blood vessels which run into the antennae. Diastole is caused simultaneously in both ampullae by the transverse muscle. Systole is produced passively by the elasticity of the wall of the ampullae and minute accessory tendons. Both elastic structures contain fine unbanded extracellular filaments.

The antennal vessels possess two distinct regions: a proximal convoluted region lying within the hemocoel of the head and a narrower distal region running through the antenna and opening near the antennal apex. The length of the proximal portion increases markedly during ontogeny in correlation with the growing antenna. Its wall consists of a high‐prismatic epithelium ensheathed by a thick layer of collagen fibrils. The structure of the wall cells is comparable to that found in some salt transporting epithelia: it shows a polar organization with basal infoldings, a large number of mitochondria, and typical arrangement of the junctions or mitochondrial‐scalariform junctional complexes. The possible physiological function of this epithelium in ionic or osmoregulation of the hemolymph entering the antenna is discussed. The wall of the distal vessel region consists of a flat single‐layered epithelium and seems to be specialized only for delivery of hemolymph to antennae. The structure and function of the antennal heart in cockroaches is compared to that found in other insects.
Autolysis and heterolysis of the epidermal cells in anuran tadpole tail regression
Authors: Kinoshita Tsutomu , Sasaki Fumie , Watanabe Kyozo
Published: February 2005

Autolysis and heterolysis of the degenerating epidermis of the tail fin of Rana japonica tadpoles during spontaneous metamorphosis were observed by transmission and scanning electron microscopy. In the early climactic stages of metamorphosis (st. 19–20), the outermost epidermal cells developed vacuoles that were acid phosphatase positive and showed apparent breakdown of the cell membrane. The cells shrunk, perhaps due to the rupture of the cell membrane, and sloughed off without typical cornification. As tail resorption proceeded, autolysis of the epidermal cells spread towards the inner layers, in which some epidermal cells lost desmosomal junctions. They also displayed atrophic figures with condensed cytoplasm, breakdown of the cell membrane, and pycnotic nuclei. Lymphocytes, neutrophils and macrophages were already present in the basal layers of the premetamorphic epidermis (st. 10). Based on ultrastructural observation, blood cells could be distinguished from autolysing epidermal cells. Only a few blood cells were found in the early climactic stages of metamorphosis (st. 19–20), but the number of the blood cells, especially macrophages, greatly increased during the final stages of metamorphosis (st. 23–24). During the final stages, many macrophages were observed to phagocytose the autolysing epidermal cells by projecting slender pseudopodia into the inner epidermis. Macrophages also were observed to pass through the degraded basal lamella. These results suggest that not only autophagy but also heterophagy of the epidermal cells by the macrophages is a major process in the regression of the tail fin epidermis.
Salivary gland ultrastructure of the unfed adult and feeding female ofHaemaphysalis (Rhipistoma) leachi(Ixodoidea: Ixodidae)
Authors: El Shoura Samir M.
Published: February 2005

The paired salivary glands of unfed adultHaemaphysalis (Rhipistoma) leachicontain one type of agranular and three types of granular alveoli connected to a salivary duct system. Type I agranular alveoli consist of one large, central cell surrounded by peripheral cells with numerous basal membrane infoldings indicative of epithelia involved in fluid transport. Glycogen particles, lipid‐like droplets, and the parallel pattern of infolded membranes disappeared from the peripheral cells during feeding. Types II, III, and IV granular alveoli contain some agranular interstitial epithelial cells, cap cells, and fundus cells, but are predominantly composed of structurally different granular cell types a, b, c, d, e, and f. Agranular cells develop during the early stages of feeding. Granular a, c, e, and f cells release their granules directly after attachment to the host and possibly are involved in cement secretion required for firm attachment to it. The b cell granules are replaced by b1filamentous granules during feeding. Golgi bodies and rough endoplasmic reticulum (RER) participate in the formation of most types of granules. The d cells contain lamella‐like structures and condensing vacuoles, probably responsible for lysosome formation. The main salivary duct and all types of alveoli are innervated by neurosecretory axons.
Ultrastructure of salivary glands ofOrnithodoros (Ornithodoros) moubata(Ixodoidea: Argasidae)
Authors: El Shoura Samir M.
Published: February 2005

The paired salivary glands of unfed adultOrnithodoros (Ornithodoros) moubataare composed of type I (agranular) and type II (granular) alveoli. Type I alveoli consis of one large central cell surrounded by peripheral cells having the morphology of fluid‐transporting epithelia. Type II alveoli contain granular and agranular cells; the former are comprised of morphologically distinct types of cells (a, b, and c) containing granules of different structures and chemical composition with respect to polysaccharide and protein. The agranular cells are the interstitial and cap cells. Golgi bodies and rough endoplasmic reticulum (RER) are found in all granular cells and apparently are involved in granule formation. No appreciable structural changes were observed in type I alveoli during or after feeding. Type c cell granules are released before granules from types a and b cells and may contain anticoagulant substances that promote the blood flow of the host during the tick feeding. Although the cap cells are not structurally affected by feeding, interstitial cells are developed into transporting epithelia.
Developmental events of the pectoral muscle in rainbow trout larvae (Salmo gairdneri)
Authors: Henderson Vernon
Published: February 2005

Skeletal muscles of developing pectoral fins in rainbow trout larvae (Salmo gairdneri) were analyzed by electron microscopy. Large, branched mitochondria were dominant structures in developing myotubes. Mitochondria were associated with the tubular system (T and SR). New mitochondria arose from old ones when the latter extruded whorls of paired membranes surrounding a nonmembranous core. The core was comprised in part of a dense material, presumably, DNA. The developing muscles were characterized by two sets of caveolae which provided the major contributions to the tubular system. Large caveolae gave rise to elements traditionally designated as SR tubules but which later lost their exterior connections. Small caveolae gave rise to small diameter tubules that appear to be analogous to T tubules, which maintained connections with the exterior. Both tubular elements abutted mitochondria. The two elements ran parallel to each other and intersected with each other to form junctions. Each set of elements possessed intratubular junctions.
Architecture of a lamellicorn flagellum (Phyllopertha horticola, scarabaeidae, coleoptera, insecta)
Authors: Ågren Lennart
Published: February 2005

The distal three of the seven flagellar segments of the scarabaeid beetle Phyllopertha horticola are lamelliform, gathered into a club, and possess five sensillar fields that are packed with sensilla placodea. The most proximal surface of the club bears only hair‐shaped sensilla. On the inner four sensillar fields a narrow central elongated zone houses pit organs and cavities with sunken sensilla placodea and other sensilla. The most distal, fifth sensillar field is smooth. The sensilla placodea seem to be of several types. The only distinct difference between the sexes is the shorter and more rounded lamellae of the female. The total count of sensilla placodea in males outnumbers that of the females by about 60%.
The fine structure of the spermatozoa of Siphonaria algesirae (Gastropoda, Pulmonata)
Authors: Azevedo Carlos , Corral Laura
Published: February 2005

The sperm of Siphonaria algesirae (Gastropoda, Pulmonata), a species with internal fertilization, was studied by light and electron microscopy. The spermatozoon is a very long, uniflagellate cell composed of a conical head with an apical acrosome, a midpiece with a helically coiled external sheath containing a complex mitochondrial derivative with a wavelength of ∼ 5.5 μm, and an endpiece. There are no axonemal microtubules. Instead, nine homogeneous coarse fibers with transverse striations in the apical zone project toward the anterior section of the midpiece. In the posterior zone of the midpiece the coarse fibers are differentiated in a common microtubular axoneme. The complex mitochondrial derivative of the midpiece shows an organized group of 100 Å diameter spherical particles. Externally the midpiece is surrounded along its length by a cylinder formed by two membranes. A complex structure separates the transitional zone between the midpiece and the endpiece.
Ovarian cycle in the frog Rana cyanophlyctis: A quantitative study of follicular kinetics in relation to body mass, oviduct, and fat body cycles
Authors: Pancharatna M. , Saidapur S. K.
Published: February 2005

In Rana cyanophlyctis, all stages of oocyte development are present throughout the year owing to continuous and asynchronous gametogenetic activity, but quantitative differences occur in the frequency distribution of the first growth phase (FGP) and second growth phase (SGP) oocytes. The number of SGP oocytes influences ovarian weight; therefore, seasonal changes in the number of SGP oocytes and ovarian mass are correlated. Mean ovarian weight and gonadosomatic index follow comparable changes during the annual cycle. The body mass of the frog undergoes only minor seasonal variations. Also, the body mass does not influence the number of oocytes in the frog.

Small FGP oocytes always formed the dominant type in the ovary. Only 20–0% of FGP oocytes were recruited to SGP stage during the prebreeding months (March–April). The breeding season extends over 2– months (July–September) and an adult R. cyanophlyctis spawns 3,000–,500 eggs of 1,300–1,350 μm diameter in size. The breeding is not followed by any resting period, and therefore oogonial proliferation and recruitment of FGP oocytes start soon after the breeding months (October‐December). Atretic oocytes are present in all months but their number is greatest during prebreeding and breeding months. The frequency distribution of oocytes in the right and the left ovaries is identical. The oviducts undergo seasonal changes that are correlated with ovarian weight, whereas the fat body cycle is inversely related to ovarian weight.
Fine structure of the statocyst sensilla of the mysid shrimp Neomysis integer (Leach, 1814) (Crustacea, Mysidacea)
Authors: Espeel Marc
Published: February 2005

The fine structure of the statocyst sensilla of Neomysis integer was investigated. The statocyst contains about 35 sensilla, which are composed of two bipolar sensory cells, nine enveloping cells, and a seta.

The sensory cells consist of an axon, a perikaryon, and a dendrite. The dendrite contains a proximal segment with a ciliary rootlet and at least one basal body, and a distal segment with a ciliary axoneme (9 × 2 + 0) at its base. The distal segment extends along the peripheral wall of the seta and is in close contact with the wall of the hair shaft.

The enveloping cells surround the proximal and distal segments of the dendrite. The innermost enveloping cell contains a scolopale rod. It surrounds the receptor lymph cavity and secretes flocculent material into this cavity. From the tip of the cell a dendritic sheath, which encloses the distal segment of the dendrite, emerges. A peculiar feature of the second enveloping cell is the presence of a scolopale‐like rod, which is more slender and less pronounced than in the first enveloping cell.

The seta consists of three parts: a socket, a tubular midpart, and a gutter‐like apical part, the tip of which penetrates into the statolith. The seta shows over its full length a bilaterally symmetrical axis that is coplanar with the plane in which the seta is bent toward the statolith.

The structure of the seta and the position of the distal segments provide morphological evidence for directional sensitivity of the sensilla and for the magnitude of shear on the setal wall being an adequate stimulus.
The role of a sertoli cell actin‐myosin system in sperm bundle formation in the ratfish, Hydrolagus colliei (Chondrichthyes, Holocephali)
Authors: Stanley Hugh P. , Lambert Charles C.
Published: February 2005

Sertoli cells in the ratfish entirely surround a clone of spermatids to form a spermatocyst. As spermiogenesis proceeds within the cyst cavity, the acrosome areas become apposed to the Sertoli cell plasma membrane lining the spermatocyst. The spermatids elongate and are gathered into an increasingly compact bundle oriented with acrosomal tips directed toward the Sertoli cell base. As all acrosome areas move closer together, Sertoli cell microfilaments oriented parallel to the long spermatid axis appear and increase in concentration. Actin and myosin were demonstrated in the microfilament area with fluorescent antibodies and NBD‐Phallacidin. Simultaneously, endocytosis of Sertoli cell membrane between spermatid attachment sites removes the intervening membrane and allows the latter sites to approach each other. Sertoli cell endocytosis is spatially and temporally related to a unique projection at the basal rim of each acrosome. During midspermiogenesis, structured intercellular material appears between the Sertoli cell and the acrosomal region of each spermatid. Its periodicity is closely related to periodic arrangement of Sertoli cell actin and material within the spermatids. These attachment sites move together upon endocytosis, gathering a clone of spermatids into a closely packed bundle.
An ultrastructural study of larval settlement in the sea anemone Urticina crassicornis (Cnidaria, Actiniaria)
Authors: Stricker Stephen A.
Published: February 2005

Laboratory‐reared larvae of the sea anemone Urticina (= Tealia) crassicornis have been examined by electron microscopy prior to and following settlement on algal substrata. At 18 days postfertilization, the free‐swimming planula larva measures about 600 μm long. A stomodaeal invagination occurs at the narrow end of the larva and connects with a solid mass of endoderm in the core region. The endoderm possesses septa with well‐developed myonemes and is situated subjacent to a thin sheet of mesoglea. The uniformly ciliated ectoderm that constitutes the outer layer of the larva contains: (1) spirocysts, (2) nematocysts, (3) mucus, (4) three types of membrane‐bound granules, (5) a basiepithelial nerve plexus, and (6) a few nongranular cells that may represent sensory neurons. Within several minutes after the introduction of the algal substratum, the planula characteristically directs its broadened aboral end toward the alga and secretes a refractile sheet of material. As the aboral end attaches to the substratum, the larva becomes noticeably shorter along its oral‐aboral axis, presumably owing to the contractions of myonemes that are located within the endodermal septa. All three types of granules and the ectodermal mucoid substances are exocytosed during settlement, but spirocysts and nematocysts characteristically remain undischarged. Ovoid, PAS+ granules are believed to be at least partly responsible for adhesion, since these granules are concentrated at the aboral end prior to settlement and are somewhat similar in ultrastructure to putative viscid granules produced by other species. Contrary to a previous report based on light microscopy, no discrete sensory organ is evident in serial sections of the aboral ectoderm. The ability of planulae to detect suitable substrata appears to depend instead on sparsely distributed sensory cells that occur throughout the larval ectoderm.
The hemocytes of Heliothis armigera: Ultrastructure, functions, and evolution in the course of larval development
Authors: Essawy M. , Maleville A. , Brehélin M.
Published: February 2005

Five types of hemocytes, prohemocytes, typical plasmatocytes, coagulocytes, spherule cells, and oenocytoides, have been defined in the last larval instar of Heliothis armigera on the basis of ultrastructural microscopy, smears, and optical phase‐contrast microscopy. Modifications in typical plasmatocytes and coagulocytes have been evidenced in the course of development in this instar, which suggests that these hemocytes are involved in physiological processes of development. Only coagulocytes exhibit endocytotic capacities. Phenoloxidase activity was observed in oenocytoides.
Fat distribution in the skin of bottlenose dolphins (Tursiops truncatus and Tursiops gilli)
Authors: Stromberg Melvin W.
Published: February 2005

Frozen sections stained with Oil‐red‐O and semithin (0.5 μm) plastic sections stained with toluidine blue revealed an abundance of fat globules of various sizes in all strata of the epidermis of bottlenose dolphins (Tursiops truncatus and T. gilli). The fat was rather evenly distributed but sometimes appeared as circumscribed areas of heavier concentration involving hundreds of cells (as seen in a single plane). Occasionally, there were smaller groups of epidermal cells heavily loaded with lipid. The dermis presented a unique phenomenon in the presence of abundant extracellular fat distributed among the collagen bundles as droplets of various sizes or as larger, irregularly shaped lipid particles that seemed to conform to the spaces between collagen bundles. These lipid particles were sometimes seen to be closely applied to the dermal surface of the stratum basale. Equally unusual was the presence of lipid particles of various sizes and shapes in the lumen of some of the vessels of the dermal papillae. Granular cells resembling mast cells were commonly seen in the papillary dermis and some were closely associated with lipid particles. Blood vessels of the reticular dermis tended to have collections of lipid droplets in the loose connective tissue often found adjacent to the tunica adventitia. It is postulated that the extracellular dermal lipids (probably mainly triglycerides) are broken down to free fatty acids that diffuse into the basal layer of the epidermis and are there resynthesized into triglycerides. Possible uses for the epidermal lipids are discussed.
The unique fibrillar matrix of the marine sponge Stelletta grubii
Authors: Simpson Tracy L. , Langenbruch Paul‐Friedrich , Scalera‐Liaci Lidia
Published: February 2005

In this astrophorid sponge, both intercellular fibrils and spongin microfibrils are elaborated with the former forming exceptionally dense arrangements throughout much of the matrix. Fibrils are very dense below the surface where they surround the small silica asters and throughout the cortex in the form of bundles that can form pseudo‐plywood arangements. In the endosome, fibril bundles are isolated and fewer in number. The surfaces of the large silica spicules are uniquely encased by intercellular fibrils or compacted intercellular fibrils that form a type of “fibrillar spongin” or spongin microfibrils intermixed with fibrils. Well developed microfibrillar spongin, intermixed with some fibrils, encases larger spicules below the sponge surface within the tissue and extends above the tissue surrounding spicules that emerge from the sponge thus placing this fibrillar matrix in direct contact with the sea water. The results of other studies suggest that the fibrils and microfibrils of this species are collagenous. The elaboration of these special matrices indicates that the differentiation of spongocytes (which secrete microfibrils) is weak and that the activity of lophocytes (which secrete fibril bundles) is highly labile. The variability of the fibrillar arrangements in this species supports the view that astrophorid sponges are possibly important for understanding the phylogeny of the organic skeletal matrix of sponges.
The fine structure of the lateral‐line organs of larval Ichthyophis (Amphibia: Gymnophiona)
Authors: Wahnschaffe Ulrich , Fritzsch Bernd , Himstedt Werner
Published: February 2005

Light and electron microscopic observations of the lateral‐line organs of larval Ichthyophis kohtaoensis confirmed earlier reports of the occurrence of two different types of lateral‐line organs. One type, the ampullary organ, possesses 15–26 egg‐shaped sensory cells. Each sensory cell extends a single kinocilium surrounded by a few microvilli into the ampullary lumen. This is in contrast to the ampullary organs of urodele amphibians that contain only microvilli. The second type of organ, the ordinary neuromast, has 15–24 pear‐shaped sensory cells arranged in two to three rows. Each sensory cell shows a kinocilium that is asymmetrically placed with respect to both a basal plate and approximately 60 stereovilli. The sensory cells of ampullary organs are always separated by supporting cells; those of neuromasts are occasionally in contact with one another. Numerous (neuromasts) or few (ampullary organs) mantle cells separate the organs from the epidermal cells. Only afferent synapses are found in the ampullary organs whereas vesicle‐filled fibers together with afferent nerve terminals are found in neuromasts. Both organs contain similarly sized presynaptic spheres adjacent to the afferent fibers. It is suggested that the neuromasts have a mechanoreceptive function, whereas the ampullary organs have an electroreceptive one.
Variations of the cephalic muscles in the colubrid snake genera Entechinus, Opheodrys, and Symphimus
Authors: Cundall David
Published: February 2005

The cephalic muscles in three species of Entechinus, two species of Opheodrys, and Symphimus mayae display patterns of interspecific variation that are largely congruent with patterns of variation previously described for the skulls of these species. This congruence does not stem from direct correlation between the shapes of associated bones and muscles. In these colubrid snakes, most interspecific variations in muscle form involve changes in the shape or relative position of attachment points that appear unrelated to changes in the gross form of the bony surfaces forming the attachment points and produce no major changes in the architectural array of fibers in the muscle. Data presented here, combined with information from previous comparative studies of colubroid cephalic muscles, support the hypothesis that these muscles are limited in their potential variability by factors favoring parallel arrangements of fibers.
Ultrastructural aspects of the surface coatings of eggs and larvae of the starfish, Pisaster ochraceus, revealed by alcian blue
Authors: Crawford B. , Abed M.
Published: February 2005

Eggs of the asteroid Pisaster ochraceus demonstrate cortical granules, a thick vitelline membrane, and a poorly stained jelly coat similar to that seen on the eggs of other echinoderms. When fixed in the presence of alcian blue the jelly coat is seen to be made up of three regions, an inner layer consisting of a meshwork of fibres, a middle layer of thicker fibres, and a dense outer layer. At fertilization the cortical granules release their contents into the potential space between the vitelline layers and a low fertilization membrane consisting of the vitelline layer and a dense component of the corticle granule is formed. Initially the remaining contents of the corticle granules form an amorphous hyaline layer that fills the space between the plasma membrane and the fertilization membrane. At hatching a distinct hyaline layer is present. It persists at least to the bipinnaria stage and consists of four distinct layers. A similar layer is also located over much of the early embryonic endoderm but is lost from the regions involved in the formation of the mesenchyme cells, coelom, and mouth just before these events take place. Numerous large clear vesicles are located in the apex of all cells associated with a hyaline layer. Where the hyaline layer is lacking, only scattered vesicles are present suggesting that the vesicles may be involved in maintenance of the layer. Attempts to identify elements of the hyaline layer by immunofluorescence demonstrated that it appears to bind both antisera and control sera in a nonspecific manner.
An ultrastructural analysis of coelomogenesis in the hoplonemertine Prosorhochmus americanus and the polychaete Magelona sp.
Authors: Turbeville J. McClintock
Published: February 2005

Formation of lateral vessels in the esophageal region of Prosorhochmus americanus embryos and coelomogenesis in the pygidial region of larval Magelona sp. are examined and compared. Earliest vessel rudiments of P. americanus are composed of a compact band of mesodermal cells (mesodermal band), lying on a layer of extracellular matrix (ECM) and lacking intercellular junctions. Rudiments are surrounded by presumptive muscle cells. Rudiments at later stages of differentiation possess lumina of differing sizes formed by a separation of apposing cell apices (schizocoely). Aohagrens junctions are apparent between lining cels of vessels following cavitation, and overlying muscle cells exhibit many myofilaments. Mesodermal bands of the recognized coelomate, Magelona sp. consist of glycogen‐rich, mesodermal cells resting on ECM and joined by adhaerens junctions. Some of the cells possess a rudimentary cilium. Coelom formation occurs as a splitting of the cell band as is the case for P. americanus. Recognition of an accepted mode of coelomogenesis in P. americanus, correlated with morphological details of adult nemertine vessels, affirms the view that nemertine vessels are coelomic homologues.
Morphology and function of the feeding apparatus of the lungfish, Lepidosiren paradoxa (Dipnoi)
Authors: Bemis W. E. , Lauder George V.
Published: February 2005

The feeding mechanism of the South American lungfish, Lepidosiren paradoxa retains many primitive teleostome characteristics. In particular, the process of initial prey capture shares four salient functional features with other primitive vertebrates: (1) prey capture by suction feeding, (2) cranial elevation at the cranio‐vertebral joint during the mouth opening phase of the strike, (3) the hyoid apparatus plays a major role in mediating expansion of the oral cavity and is one biomechanical pathway involved in depressing the mandible, and (4) peak hyoid excursion occurs after maximum gape is achieved.

Lepidosiren also possesses four key morphological and functional specializations of the feeding mechanism: (1) tooth plates, (2) an enlarged cranial rib serving as a site for the origin of muscles depressing the hyoid apparatus, (3) a depressor mandibulae muscle, apparently not homologous to that of amphibians, and (4) a complex sequence of manipulation and chewing of prey in the oral cavity prior to swallowing. The depressor madibulae is always active during mouth opening, in contrast to some previous suggestions.

Chewing cycles include alternating adduction and transport phases. Between each adduction, food may be transported in or out of the buccal cavity to position it between the tooth plates. The depressor mandibulae muscle is active in a double‐burst pattern during chewing, with the larger second burst serving to open the mouth during prey transport. Swallowing is characterized by prolonged activity in the hyoid constrictor musculature and the geniothoracicus.

Lepidosiren uses hydraulic transport achieved by movements of the hyoid apparatus to position prey within the oral cavity. This function is analagous to that of the tongue in many tetrapods.
The sphincter of the efferent filament artery in teleost gills: I. Structure and parasympathetic innervation
Authors: Bailly Yannick , Dunel‐Erb Suzanne
Published: February 2005

Previous studies have shown the existence of a sphincter in the efferent filament artery of the teleost gill and its constrictory response to acetylcholine (ACH) and vagal stimulation. This study deals with the muscular organization of this sphincter and the distribution of its innervation as elucidated by degeneration methods and cytochemistry. The sphincter innervation is supplied by the protrematic vagus nerves. Nerve endings filled with cholinergic‐type vesicles are located in close association with the adventitial smooth muscle cells and display a strong acetylcholinesterase (ACHE) activity. Section of the protrematic vagus nerve induces a nearly complete degeneration of the sphincter innervation. ACHE‐positive nerve cell bodies are present both in the sphincter area and in the protrematic vagus nerve. These results suggest that innervation of the sphincter in the efferent filament artery is cholinergic through the activity of postganglionic axons of the parasympathetic system.
The sphincter of the efferent filament artery in teleost gills: II. Sympathetic innervation
Authors: Dunel‐Erb Suzanne , Bailly Yannick
Published: February 2005

In addition to the cholinergic innervation described in the sphincter of the efferent filament arteries (Bailly and Dunel‐Erb, ′86), an aminergic component has been demonstrated by specific techniques. The Falck fluorescence technique reveals a network of nerve fibers displaying a green fluorescence characteristic of catecholamines. At the ultrastructural level two types of fibers are present, one with clear vesicles and another with densecored vesicles. Axo‐axonal synaptic relationships exist between the two types. Results of 5‐ and 6‐OHDA (hydroxydopamine) treatments confirm the presence of an aminergic component.

These observations support the notion of a dual innervation: cholinergic and adrenergic of, respectively, parasympathetic and sympathetic origin. The presence of presynaptic modulation is suggested. The aminergic component could inhibit or reduce the release of acetylcholine from cholinergic nerve endings. These results suggest that the sympathetic innervation modulates the vasoconstriction effect of the parasympathetic component.
Morphology and function of the tongue and hyoid apparatus in Varanus (varanidae, lacertilia)
Authors: Smith Kathleen K.
Published: February 2005

The morphology and function of the tongue and hyoid apparatus in Varanus were examined by anatomical and experimental techniques. Morphological features unique to Varanus include a highly protrusible tongue that has lost a roughened dorsal surface, an exceptionally strong and mobile hyobranchial apparatus, a well‐defined joint between the ceratohyal and anterior process, and a series of distinct muscles inserting at the anterior hyobranchial region. Varanus is also unusual among lizards in a number of feeding behaviors; it ingests prey entirely by inertial feeding, as the tongue does not participate in food transport. Further specializations include an increased reliance on hyobranchial movements in drinking and pharyngeal packing and compression. The long, narrow tongue is most likely related to the mechanics of tongue protrusion; the increased amount, strength, and complexity of hyobranchial movement is related to the fact that the hyobranchium in Varanus replaces the tongue in many functions. Previous hypotheses for the origin of these adaptations are discussed, and the difficulties of attributing these specializations to any specific scenario of adaptation or constraint are emphasized.
An atlas of the brain of the horseshoe crab Limulus polyphemus
Authors: Chamberlain Steven C. , Wyse Gordon A.
Published: February 2005

An atlas of the brain of the horseshoe crab Limulus polyphemus is developed. All of the neuronal groups are identified and named, and regions of neuropil are segregated and named where possible. The nomenclature incorporates functionally neutral earlier names and assigns geographical names to newly distinguished structures. The atlas provides a basis for correlating the results of neuroanatomical, neurophysiological, and neurochemical studies, which yield information about individual neurons or groups of neurons in this species
The fate and role of openings formed in the mesentery of bullfrog tadpoles, with reference to the contour of mesothelial cells
Authors: Sugimoto Keiji , Fujii Sachiko , Ichikawa Yasuaki , Nakamura Itsuo
Published: February 2005

Using morphological techniques, histological changes of the mesentery were observed during the development of the bullfrog, Rana catesbeiana. The tadpoles of this species had many openings all over the mesentery from the duodenum through the large intestine. Most of the openings were elliptical and less than 3 × 2 mm in size. The openings became remarkably decreased in size and number with rapid narrowing of the mesentery occurring during the period of metamorphic climax, and had almost completely disappeared by the end of metamorphosis. Appearance and disappearance of the openings were closely correlated with the changes in the dimensions of the mesentery. Furthermore, in parallel with these changes in the openings, a noticeable alteration occurred in the shape of the mesothelial cells of the mesentery. In tadpoles having no mesenteric openings, the mesothelial cells had a polygonal contour, which became transformed once the openings were formed in the mesentery. The shapes of the transformed cells were classified into two types, one having many radiating cell processes and the other a very slender and spindle‐shaped contour. Both types of cells eventually became transformed into a definitive type of cell exhibiting a roundish polygonal contour by the end of metamorphosis. From these findings it was concluded that the growing mesentery might, of necessity, give rise to the openings and transformation of the mesothelial cells to enable rapid lengthening and shortining of the intestinal tract to occur during the postembryonic development of anuran amphibians.
Morphology of the tongue in the tuatara, Sphenodon punctatus (Reptilia: Lepidosauria), with comments on function and phylogeny
Authors: Schwenk Kurt
Published: February 2005

The morphology and histology of the tongue in Sphenodon punctatus are described and used to infer function and to determine character state polarities in lepidosaurs. The tongue lacks an anterior notch and is covered with filamentous papillae, including specialized gustatory papillae containing taste buds. Lingual glands are restricted to mucocytes covering the papillae. Three intrinsic tongue muscles are identified and shown to be discrete fiber systems and not merely elaborations of the M. hyoglossus. These muscles interact with a connective tissue skeleton, particularly three septal planes, to cause changes in tongue shape. Tongue protrusion is probably caused by hyoid protraction and contraction of posterior genioglossus fibers; retraction by hyoid retraction, hyoglossus contraction, and contraction of anterior genioglossus fibers.

It is argued that taste is important in prey discrimination and possibly in courtship. Vomeronasal function is probably mediated by inhalation and not tongue movement.

Insertion of genioglossus fibers into the buccal floor is a derived feature of lepidosaur tongues. Derived features of squamate tongues include an anterior bifurcation, a divided genioglossus comprising medial and lateral portions, ventral transverse and circular muscle fiber systems around the hyoglossus, and the presence of a median septum. The tongue of the squamate family Iguanidae shares many plesiomorphic features with Sphenodon.
Ultrastructure of the ileum of Locusta migratoria
Authors: Peacock A. J.
Published: February 2005

The epithelium of the ileum of Locusta migratoria is composed of a single layer of columnar cells surrounded on the luminal side by cuticle and on the haemocoel side by a circular muscle layer. Where the circular muscles contact the epithelium, longitudinal muscles are present and the epithelium is slightly reduced. Elsewhere, a subepithelial sinus separates the epithelium from the circular muscle layer. The epithelial cells are characterised by extensive infoldings of the apical and basal cell membranes, which in the latter case, produce a maze of interconnecting channels and spaces. Mitochondria are closely associated with both apical and basal infoldings, although the bulk of these organelles is located in the cytoplasm underlying the infoldings of the apical plasma membrane. Vesicles of assorted sizes occur throughout the cytoplasm. They are particularly abundant in the apical region, where they appear to be produced by pinocytosis. Larger vesicles, containing either material of varying electron density or smaller vesicles, occur in the medial and basal regions of the cells. The contents of some of these vesicles have, in section, a lamellar appearance, composed of concentric layers of material. Similar vesicles are present in the basement membrane as well as the cells and connective tissue of the subepithelial sinus. Microtubules and groups of ribosomes commonly occur throughout the cytoplasm, and lipid‐like droplets are also present in some of the cells. Ultrastructural features of the epithelial cells are discussed in relation to current knowledge of the function of the ileum.
Ultrastructure of embryonic anal processes in Girardinichthys viviparus (Cyprinodontiformes, Osteichthyes)
Authors: Schindler Joachim F. , De Vries Uwe
Published: February 2005

Scanning and transmission electron microscopy were used to examine the morphology of the perianal processes (trophotaeniae) of goodeid embryos (Girardinichthys viviparus) at two stages of gestation. The epithelial surface of trophotaeniae is composed of two cell types, one of which shows distinct features associated with absorptive activity. Such cells are characterized by microvilli, abundant mitochondria, and an agranular tubulolamellar network. Micropinocytosis at the apical surface is relatively rare. The brush border membranes contain high levels of alkaline phosphatase. The cells of the second type are the minor component of the trophotaenial epithelium. Their surface is distinct, due to the presence of microridges rather than microvilli. The reticulate arrangement of the cells gives rise to intercellular spaces which occasionally are very large. These interstices are populated with leukocytes. The histological appearance of these sections indicates that this tissue is involved in gas exchange. Embryos at very early stages of development possess similar epithelia which are differentiated to a lesser extent. The connective tissue in some parts of the processes shows structural modifications. It is densely packed with numerous leukocytes occupying the spaces between the cytyoplasmic ramifications of the stroma cells. Possible roles of the trophotaeniae in absorption, respiration, excretion, and the acquisition of immunity are discussed, and it is concluded that the perianal processes of the Goodeidae are more than just trophic embryonic structures.
Ultrastructural aspects of mouth formation in the starfish Pisaster ochraceus
Authors: Abed M. , Crawford B. J.
Published: February 2005

Early events during mouth formation in embryos of the starfish Pisaster ochraceus have been studied with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Embryos examined by TEM were fixed in glutaraldehyde with Alcian blue, a dye which preserves extracellular materials. Initially, mesenchyme cells migrate off the tip of the archenteron, leaving a defect in the cell layer that is covered by the basal lamina. This region of “naked” basal lamina bulges into the blastocoele and forms a hemispherical blister. At the same time that this is occurring, filamentous and conical processes extend from the inner surface of the presumptive stomodeal ectoderm cells which are located directly opposite the bulge of basal lamina. These processes penetrate the ectodermal basal lamina and project “naked” plasmalemma into the blastocoele. Shortly after this, the blister of endodermal basal lamina becomes irregular in shape, and scattered cells are found both within the blister and between it and the presumptive stomodeal ectoderm cells. Processes of endodermal cells appear to make contact with the filamentous processes of the stomodeal ectoderm cells. In other embryos which appear to be at a slightly later stage, the free basal lamina is conical in shape and is associated with at least one conical ectodermal process. In yet other embryos, the free endodermal basal lamina is either in contact with several other large processes forming a circular region of contact, or the free endodermal and ectodermal basal laminae are fused at the edge of the circle. Degeneration of both the ectodermal and endodermal basal laminae located within the circle, and subsequent invagination of the stomodeal ectoderm, appear to complete this process. The pulsations of stomodeal ectodermal cells seen throughout early stages in mouth formation may be involved in these events.
Ontogeny of cranial ossification in the eastern newt, Notophthalmus viridescens (Caudata: Salamandridae), and its relationship to metamorphosis and neoteny
Authors: Reilly Stephen M.
Published: February 2005

The ontogenetic sequence of cranial osteogenesis through adulthood is described in samples of newts from completely metamorphosing and partially neotenic populations. Cranial ossification proceeds in the same sequence in both samples. Seven stages of cranial development are described on the basis of conspicuous events that occur during ontogeny. These include four larval stages, metamorphs, efts, and adults. Neotenic adults have skulls that are metamorphosed completely and indistinguishable from the skulls of non‐neotenic adults. Neoteny in these newts does not involve the skull and is limited to the postmetamorphic retention of some gill structures and, thus, is termed “limited neoteny.” The evolution of limited neoteny in newts as a correlated response to the inhibition of land‐drive behavior is discussed.
The fibromuscular basket (sporta perimedullaris musculosa) in renculi of kidneys from the ringed seal, Phoca hispida (Pinnipedia)
Authors: Newstead J. D. , Munkacsi I. M.
Published: February 2005

The medulla of renculi from kidneys of Ringed seals (Phoca hispida) is completely enclosed by cortex except at the hilum. Within the renculus, the fibromuscular coat of the calyx separates from the transitional epithelium at the level of the corticomedullary junction, where the intrarencular arteries also diverge into the parenchyma. Flat ribbons of this stromal tissue form an arborized framework near the medullary side of the intrarencular arteries and the larger of the arcuate arteries derived from them. The ribbons, which are clearly distinct from periarterial connective tissue, are composed of coarse collagenous fibers, elastic fibers, and smooth muscle cells, all oriented in the direction of the long axes of the ribbons, and myofibroblasts. The proportion of smooth muscle cells decreases and that of myofibroblasts increases with increasing distance from the calyx. At the base of the medullary pyramid, the elements of the framework diminish in width and ultimately blend with the surrounding interstitial tissue. The stromal framework, or basket, is homologous with the Sporta perimedullaris musculosa of cetacean kidneys.