bluuebunny/crossref_metadata_2025_split huggingface dataset:
The seminal receptacle and sperm storage in Cochlostoma montanum (Issel) (Gastropoda: Prosobranchia)
Authors: Giusti Folco , Selmi Maria Gloria 
Published: February 2005

AbstractFemales of Cochlostoma montanum (Prosobranchia, Cochlostomatidae) have a seminal receptacle which is not a separate diverticulum of the oviduct. The seminal receptacle derives from a differentiated portion of the renal oviduct which has an inner wall composed of only one layer of cells. These cells are of two different types, both actively involved in secretory activity. One type is represented by goblet cells filled with large vesicles containing an electron‐dense, homogeneous, and partially paracrystalline material. This material is expelled into the lumen through macro‐apocrine or holocrine types of secretion. The other type is represented by ciliated cells rich in small vesicles containing granular material. Probably neither kind of secretion has a nutritive function; rather they serve as matrix for spermatozoa that immobilize them and prevent their expulsion from the receptacular portion of the oviduct. Spermatozoa are inserted in invaginations of the apex of both these epithelial cells. The sperm plasma membrane covering the acrosome forms long digitations which expand toward the corresponding invaginations of the receptaculum cells. This type of adhesion is a novelty for Mollusca and resembles that in seminal receptacles of some Annelida.
Histochemical and biochemical studies of the hepatopancreas peroxidase of the freshwater crayfish, Cambarus robustus
Authors: Merrill D. P. , Reife R. A. , Tiersch T. R. , Austin R. S. 
Published: February 2005

AbstractCrayfish are among the few invertebrate species reported to possess endogenous peroxidase activity. The enzyme is found within the hepatopancreas, the principal digestive and absorptive organ of the crustacean body. Cambarus robustus, a species found in abundance in the streams of western New York, was used in this study. Homogenates of 18 hepatopancreases were assayed for peroxidase activity using guaiacol as the substrate. Although present in all organs, peroxidase activity displayed a greater than 50‐fold difference between the two extremes (0.05–;2.72 units/mg protein). Histochemical examination using diaminobenzidine revealed peroxidase activity within a line of cells extending along the distal two‐thirds of the lengths of all hepatopancreatic tubules. The cells function to synthesize the enzyme, sequester it within vacuoles of increasing size, and eventually secrete it into the tubule lumen. Since the tubule is constantly renewed by distal mitotic activity and concomitant proximal exfoliation, this histochemical technique permits not only the examination of the ontogeny of this peroxidase‐positive cell line, but also offers additional insight into the mechanism of hepatopancreatic tubule renewal.
Ameloblastic secretion and calcification of the enamel layer in shark teeth
Authors: Kemp Norman E. 
Published: February 2005

AbstractTooth primordia at early stages of mineralization in the sharks Negaprion brevirostris and Triaenodon obesus were examined electron microscopically for evidence of ameloblastic secretion and its relation to calcification of the enamel (enameloid) layer. Ameloblasts are polarized with most of the mitochondria and all of the Golgi dictyosomes localized in the infranuclear end of the cell toward the squamous outer cells of the enamel organ. Endoplasmic reticular membranes and ribosomes are also abundant in this region. Ameloblastic vesicles bud from the Golgi membranes and evidently move through perinuclear and supranuclear zones to accumulate at the apical end of the cell. The vesicles secrete their contents through the apical cell membrane in merocrine fashion and appear to contribute precursor material both for the basal lamina and the enameline matrix. The enamel layer consists of four zones: a juxta‐laminar zone containing newly polymerized mineralizing fibrils (tubules); a pre‐enamel zone of assembly of matrix constituents; palisadal zones of mineralizing fibrils (tubules); and interpalisadal zones containing granular amorphous matrix, fine unit fibrils, and giant cross‐banded fibers with a periodicity of 17.9 nm. It seems probable that amorphous, non‐mineralizing fibrillar and mineralizing fibrillar constituents of the matrix are all products of ameloblastic secretion. Odontoblastic processes are tightly embedded in the matrix of the palisadal zones and do not appear to be secretory at the stages investigated. The shark tooth enamel layer is considered homologous with that of other vertebrates with respect to origin of its mineralizing fibrils from the inner dental epithelium. The term enameloid is appropriate to connote the histological distinction that the enamel layer contains odontoblastic processes but should not signify that shark tooth enamel is a modified type of dentine. How amelogenins and/or enamelins secreted by ameloblasts in the shark and other vertebrates are related to nucleation and growth of enamel crystallites is still not known.
The trophotaenial placenta of a viviparous goodeid fish. II. Ultrastructure of trophotaeniae, the embryonic component
Authors: Lombardi Julian , Wourms John P. 
Published: February 2005

AbstractEmbryos of the viviparous goodeid fish Ameca spendens develop within the ovarian lumen, where they establish a placental association with the maternal organism and undergo a 15,000% increase in embryonic dry weight. The placenta consists of an embryonic component, the trophotaeniae, and a maternal component, the internal ovarian epithelium. Examination with light microscopy and with transmission and scanning electron microscopy reveals that trophotaeniae of A. splendens are extraembryonic membranes consisting of five ribbon‐like processes originating from a tube‐like mass of tissue that extends outward from the perianal region of developing embryos. There are two sets of lateral processes and a longer single median process. Trophotaeniae possess an outer epithelium that surrounds a highly vascularized core of loose connective tissue. Epithelial cells possess apical microvilli and a pronounced endocytotic apparatus. Cells of the trophotaenial epithelium are either tightly apposed along their lateral margins or separated by enlarged intercellular spaces. Regions of the trophotaenial epithelium possessing enlarged intercellular spaces are distributed in patches. The trophotaenial epithelium is continuous with the embryonic hindgut epithelium and is considered to be derived from it. Comparison of trophotaenial morphology in A. splendens with that reported in Xenotoca eiseni reveals differences in histological organization. The former possess unsheathed trophotaeniae, whereas the latter are sheathed. We postulate that the apposition of trophotaenial epithelium to the internal ovarian epithelium constitutes a placental association equivalent to a noninvasive, epithelioform of an inverted yolk sac placenta. Structural relationships of embryonic and maternal tissues of the trophotaenial placenta are discussed in relation to maternal‐embryonic nutrient transfer processes.
Functional organization of battery cell complexes in tentacles of Hydra attenuata
Authors: Hufnagel L. A. , Kass‐Simon G. , Lyon M. K. 
Published: February 2005

AbstractUltrastructural and light microscopic observations on the organization of thick and thin regions of hydra's tentacles, made on serial sections and on whole fixed, plastic‐embedded tentacles, reveal the existence of two levels of anatomical order in the tentacle ectoderm: (1) The battery‐cell complex (BCC), composed of a single epitheliomuscular cell (EMC) and its content of enclosed nematocytes and neurons; and (2) the battery cell complex ring (BCC ring), an arrangement of 4 or more BCCs into larger units organized as rings around the circumference of the tentacle. All EMCs of the distal tentacle appear to contain batteries of nematocytes, and are, therefore, called “battery cells.” Apart from battery cell complexes and migrating nematocytes, there are no other cell types in the tentacle ectoderm. Battery cells are composed of three distinct regions: the cell body, peripheral attenuated extensions and myonemes. Thick tentacle bands are composed of cell bodies, whereas thin bands are made up of attenuated extensions. Myonemes contribute to both thick and thin regions. It was confirmed that each battery cell has several myonemes, which appear to interdigitate with myonemes of other more proximal and distal battery cells, but not with battery cells of the same BCC ring. Nematocytes have several basal processes. Some processes insert between myonemes and contact the mesoglea; other processes insert into cuplike extensions of myonemes, and are connected to myonemal cups by desmosomal junctions. These observations are discussed in relation to mechanical and electrical aspects of tentacular contraction and bending.
Mineral content of the organ of Bellonci in the marine amphipod Gammarus setosus
Authors: Steele V. J. , Oshel P. E. 
Published: February 2005

AbstractCalcium is demonstrated by energy and wavelength dispersive X‐ray microanalysis to be the major component of the granules that fill the fuselli of the organ of Bellonci in Gammarus setosus. The presence of calcium was confirmed by chelation with EDTA and by other cytochemical techniques. X‐ray microanalysis indicated the simultaneous presence of iron in the region of the fuselli occupied by the calcium granules, but this could not be confirmed by cytochemical means in resin‐embedded tissue by light or transmission electron microscopy.
Muscle system organization in the echinoderms: III. Fine structure of the contractile apparatus of the arm flexor muscles of the comatulids (Antedon mediterranea)
Authors: Carnevali M. Daniela Candia , Saita Abele 
Published: February 2005

AbstractThe crinoid arm muscles consist of obliquely striated fibers with striking differences in function and in ultrastructural features. These fibers can be distinguished mainly on the basis of different myofilament arrangements (A‐ and B‐type patterns) and are variously combined at different levels (proximal, intermediate, and distal portions) of the arm. Some rare smooth fibers (C‐type) are irregularly distributed in the periphery and in the core of the bundle. The characteristic features of the A‐ and B‐type obliquely striated fibers are (1) a continuous and homogeneous structure of the Z line and (2) a very heterogeneous arrangement of myosin filaments which vary widely in size, number, and distribution from section to section. The significance of such an atypical, obliquely striated muscle may be related to the double skeletal system combination (endoskeleton and hydroskeleton) of the crinoid arms.
Secretory cells in the clitellar epithelium of Eisenia foetida (Annelida, Oligochaeta): A histochemical and ultrastructural study
Authors: Morris G. M. 
Published: February 2005

AbstractEight secretory cell types are identified in the clitellar epithelium of Eisenia foetida, of which five have been described in detail previously (i.e., the large granular, fine granular, metachromatic, orthochromatic, and small granular proteinacecus cells).The remaining three secretory cell types are mucus‐producing cells specific to the clitellar epithelium (type 3), cells associated with the chaetal follicles (type 4), and cells that occur exclusively in the tubercula pubertatis (type 5). Type 3 cells secrete a mucus containing neutral and acid mucosubstances. Ultrastructurally, type 3 cells are characterized by membrane‐bound globules 0.4 to 3.7 μm in diameter. The contents of the globules have a finely reticulate appearance. The secretion of type 4 cells contains a collagenlike protein and neutral and sulfated acid mucosubstances. Type 4 cell secretory granules are membrane bound and range in diameter from 0.8 to 1.6 μm. They contain large, electron‐dense, spheroid cores which are surrounded by parallel orientated microfibrils 14 nm in diameter. Type 5 cells give variable responses to the histochemical techniques used in the present study. An elastinlike protein is detected in about half of the type 5 cells and acid and neutral mucosubstances in the remainder. At the ultrastructural level the secretory granules vary in shape from spheroid to polygonal. Their finely, electron‐dense contents exhibit progressive swelling which results in the eventual rupture of the limiting membranes of the granules. The necks of types 3, 4, and 5 cells contain a peripheral ring of microtubles (20 ± 1 nm in diameter).
Placentation in the lizard Gerrhonotus coeruleus with a comparison to the extraembryonic membranes of the oviparous Gerrhonotus multicarinatus (Sauria, Anguidae)
Authors: Stewart James R. 
Published: February 2005

AbstractParaffin sections of an ontogenetic series of embryos of the viviparous lizard Gerrhonotus coeruleus and the oviparous congener G. multicarinatus reveal that although general features of the development of the chorioallantoic and yolk sac membranes are similar, differences are evident in the distribution of the chorioallantoic membrane in late stage embryos. An acellular shell membrane surrounds the egg throughout gestation in both species although the thickness of this structure is much reduced in G. coeruleus over that of G. multicarinatus. The initial vascular membrane to contact the shell membrane in both species is a trilaminar omphalopleure (choriovitelline membrane) composed of ectoderm, mesoderm of the area vasculosa, and endoderm. This transitory membrane is replaced by the vascularized chorioallantois as the allantois expands to contact the inner surface of the chorion. Prior to the establishment of the chorioallantois at the embryonic pole, a membrane begins to form within the yolk ventral to the sinus terminalis. This membrane, which becomes vascularized, extends across the entire width of the abembryonic region and isolates a mass of yolk ventral to the yolk mass proper. The outer membrane of the yolk pole is a nonvascular bilaminar omphalopleure (chorionic ectoderm and yolk endoderm). In G. multicarinatus the bilaminar omphalopleure is supported internally by the vascularized allantoic membrane, whereas in G. coeruleus the allantois does not extend beyond the margin of the isolated yolk mass and the bilaminar omphalopleure is supported by the vascularized intravitelline membrane. Both the chorioallantoic placenta (uterine epithelium, chorionic ectoderm and mesoderm, and allantoic mesoderm and endoderm) and the yolk sac placenta at the abembryonic pole (uterine epithelium, chorionic ectoderm, and yolk sac endoderm) persist to the end of gestation in G. coeruleus.
Cellular structure of adipose tissue in birds
Authors: Pond Caroline M. , Mattacks Christine A. 
Published: February 2005

AbstractIn a randomly collected sample of 91 wild and captive birds, in which there is no significant correlation between fatness and body mass, the total number of adipocytes is proportional to (Body Mass)0.68. The adipose tissue of larger birds consists of proportionately fewer adipocytes; therefore, the adipocytes of larger birds are larger, in relation to the fatness of the specimens, than those of the smaller species. The cellularity of the adipose tissue of predominantly carnivorous birds does not differ from that of mainly herbivorous species. The adipocytes in the abdominal cavity and around the thigh are on average 29% larger than those in the superficial and clavicular depots; however, these site‐specific differences were variable and were statistically insignificant in many of the specimens. The size of the adipocyte complement is highly variable even among specimens of a single species and similar body mass, suggesting that in birds the number as well as the volume of adipocytes might increase or decrease as the adipose tissue expands or shrinks.
Scanning electron microscopic study of the male genital tract during its highest and lowest activities in the seasonal reproductive cycle of the soft‐shelled turtle
Authors: Kumar De Tapas , Maiti B. R. 
Published: February 2005

AbstractThe objective of the present investigation was to study by scanning electron microscopy the epithelial surface structures of different segments of the male genital tract (ductuli efferentes, proximal and distal epididymes, and vas deferens) during highest (July) and lowest (January) activity in the annual reproductive cycle of the soft‐shelled turtle. The study has revealed that there are distinct regional differences in the male genital tract. The ductuli efferentes have three types of cells, long‐ciliated, short‐ciliated, and microvilli‐bordered cells. The proximal epididymis has two types of cells, microvilli‐bordered cells and smooth‐surfaced cells; the distal epididymis has only tall, smooth‐surfaced cells. The vas deferens contains both smooth‐surfaced and microvilli‐bordered cells. Cells of the genital tract in July show several differences from comparable cells in January: Ciliated cells of the ductuli efferentes have longer cilia, cells of the proximal epididymis have microvilli distended by secretory materials, and cell apices in the distal epididymis are surmounted by an abundance of huge secretory blebs. There is no discernible change in the vas deferens. The findings suggest that all segments of the male genital tract, except the vas deferens, become active in July and have regressed by January in the annual sexual cycle.
Fine structure and classification of shrimp hemocytes
Authors: Martin Gary G. , Graves Brenda L. 
Published: February 2005

AbstractThe structure of hemocytes from two species of penaeid shrimp was examined by light and electron (TEM) microscopy. Hemocytes from the two species are indistinguishable and are classified as either agranular, small‐granule, or large‐granule hemocytes. Agranular hemocytes are the smallest of the hemocytes, lack granules, compose only 5–10% of the circulating hemocytes, and are nonrefractile when examined by light microscopy. Small‐granule hemocytes are the most abundant type of hemocyte (75% of all hemocytes), appear nonrefractile, and contain a variable number (1–40) of granules (0.4 μm diameter). Large‐granule hemocytes compose 10–20% of the hemocytes. They are filled with granules (0.8 μm in diameter) that are highly refractile when examined by light microscopy and are electron‐dense when examined by TEM. Our classification scheme is based solely on the absence or presence and relative size of granules. Features used by other researchers, such as cell size, shape, and staining properties, were not used because these features are subtle and/or subjective. The proposed classification is compared with schemes developed for other decapods, and its usefulness and limitations are discussed. This scheme will serve as a basis for further studies on the maturation and physiological function(s) or crustacean hemocytes.
Structure of dactyl sensilla in the kelp crab, Pugettia producta
Authors: Hamilton K. A. , Linberg K. A. , Case J. F. 
Published: February 2005

AbstractIn the kelp crab, Pugettia producta, flat plate setae cover all but the ventral surfaces of the walking leg dactyls. Dendrites enter the setal shaft located inside the plate superstructure, and extend to a region of the setal tip that contains a system of minute pores resembling the pore systems found in chemosensory sensilla of insects. Presumably, much of the chemosensitivity of the dactyls in the kelp crab is mediated by the plate setae.In the interior of the dactyl, supporting cells and the neurons innervating plate setae, other types of setae, and other presumptive sensilla form scolopidia. Large scolopidia, containing as many as 12 dendrites, appear to innervate some of the plate setae and also large ventral rodlike setae that might be chemosensory. Two of the dendrites of large scolopidia usually have more densely packed microtubules, longer ciliary axonemes, slightly larger rootlets, and dark A fibers with arms, characteristics indicative of mechanosensory function. Some dactyl setae, therefore, could be both mechanosensory and chemosensory. Small scolopidia containing two or three dendrites that exhibit mechanosensory characteristics appear to innervate small, rodlike setae, which presumably are strictly mechanosensory. The two types of structures located on the epicuticular cap, elliptical structures resembling campaniform sensilla and small cones in pits resembling CAP organs, appear to be dually innervated and presumably are mechanosensory, although other functions are possible.The internal positions of the scolopidia, together with the support afforded by an extracellular dendritic sheath, by the scolopale, and by desmosomelike and septate junctions, may serve to protect internal portions of setal dendrites, some of which appear to remain functional in nonmolting adults that have abraded setae.
Ultrastructure of the colon of Locusta migratoria
Authors: Peacock A. J. 
Published: February 2005

AbstractThe ultrastructure of the colon of Locusta migratoria is described. The colon is lined by a thick cuticle that, for the most part, adheres to the underlying epithelium. The cuboid epithelial cells are characterized by moderate invaginations of the apical and, to a lesser extent, basal plasma membranes; the lateral plasma membranes are relatively flat. The bulk of the mitochondria are located in the apical region of the cell and are not particularly associated with any of the plasma membranes. The basal region of the cells contains much rough endoplasmic reticulum, glycogenlike granules, and a predominance of spherical, electron‐dense bodies of various sizes. Where muscle fibers make contact with the epithelium, the cells are much reduced; the cytoplasm is usually less electron‐dense, and, typically, the nucleus has a thick layer of granular material associated with the inner nuclear membrane. The apical and basal plasma membranes of the reduced epithelial cells contain numerous hemidesmosomes. The apical hemidesmosomes occur in pairs around an extracellular space that contains electron‐opaque material. The latter forms tonofibrillae that extend into the endocuticle. Bundles of microtubules are associated with the hemidesmosomes. The tubules traverse the cell from the apical to the basal region. The possible significance of these findings is discussed.