bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fine structure of the triturating devices in the food pump of Notonecta (Heteroptera: Notonectidae)
Authors: Parsons Margaret C. 
Published: February 2005

AbstractThe cibarial food pump of heteropteran insects conveys fluid food from the piercing stylets to the pharynx. In aquatic Heteroptera the pump also grinds and filters particulate matter in the food stream. The pump's sclerotized triturating devices differ from one family to the next and are often quite elaborate: because of their small size they are best studied by means of the scanning electron microscope. In Notonecta the main triturating devices occur on the transverse plates of the epipharyngeal roof of the pump. They consist of a complex anterior zone with raised nodes and bifurcating longitudinal ridges, and a simpler posterior zone with small nodules. Additional triturating surfaces occur on the hypopharyngeal floor of the pump. The oblique folds of the epipharynx, which lie anterior to the transverse plates, play only an accessory role. The fine structure of the grinding surfaces on the transverse plates of Gelastocoris (Gelastocoridae), Ambrysus (Naucoridae), and Aphelocheirus (Aphelocheiridae) is here briefly described and compared with that of Notonecta.
An ultrastructural analysis of mitosis and cytokinesis in the zygote of the sea urchin, Arbacia punctulata
Authors: Longo Frank J. 
Published: February 2005

AbstractPost‐fertilization events leading to the cleavage of the zygote of the sea‐urchin, Arbacia punctulata were examined with the light and electron microscopes. Prior to prophase of the first cleavage division, endoplasmic reticulum and annulate lamellae become organized around the zygotic nucleus to produce a crescent‐shaped structure which is defined as the streak (Harvey, '56). With the advent of prophase the streak undergoes morphogenic events which lead to the formation of the mitotic asters. During this transition there is a loss of annulate lamellae and a concomitant increase in endoplasmic reticulum. Annulate lamellae are not found as a part of the mitotic apparatus and are not again observed within the embryo until the two cell stage. During telophase, karyomeres are formed which consist of chromosomes delimited by a porous bilaminar envelope. Blastomere nuclei are produced following the fusion of the outer laminae, and subsequently by the fusion of the inner laminae of the envelopes encompassing the karyomeres.
An electron microscopic study of the tympanal organ and associated structures in the foreleg tibia of the cricket, Gryllus assimilis
Authors: Friedman Morton H. 
Published: February 2005

AbstractEarly descriptions of insect sensory organs included three presumed mechanotransducers in the tibia of Orthoptera, namely the subgenual organ, the intermediate organ, and the tympanal organ. The following study examines the fine structure of the tympanal organ in the foreleg tibia of the cricket, Gryllus assimilis. This investigation provides the first fine structure analysis of this structure and shows that the tibial tympanal organ is not a scolopophorus organ. It consists of highly modified epithelium, associated with the anterior tympanic membrane, and receives innervation from the anterior ganglion.
The fine structure of a cephalic sensory receptor in the copepod Doropygus seclusus Illg (Crustacea: Copepoda: Notodelphyidae)
Authors: Dudley Patricia L. 
Published: February 2005

AbstractA cephalic organ of presumed sensory function is described in nauplii and copepodids of the ascidicolous copepod Doropygus seclusus Illg. The receptor, located bilaterally in the anterodorsal head region, is composed of dendrites of extra optic protocerebral origin which have ciliary protrusions with basal bodies, no rootlets, and a basal infrastructure of the 9 + 0 type. The cilia do not branch and their distal terminations contain only one to four microtubules. In nauplii and free‐living copepodids, a large epidermal supporting cell encapsulates the end of one dendrite and its cilia in a sac. Other dendrites and their cilia pass through the supporting cell and, terminally, the cilia escape to form a whorled fascicle which contacts the anterolateral cephalic cuticle. The latter end organ reaches its greatest development in the second copepodid stage — the stage which infects the ascidian. All of the symbiotic stages of the copepod have only a proportionately smaller end organ of the saccular type and apparently lack the end organ consisting of whorls of ciliary ends. The function of the receptor is unknown, but it is suggested that the end organ which disappears in the symbiotic stages functions in second copepodids in host recognition.
Distribution of monoamine‐containing neurons in the brain stem of the frog, Rana temporaria
Authors: Parent A. 
Published: February 2005

AbstractThe distribution of monoamine (catecholamine and 5‐hydroxytryptamine)‐containing nerve cell bodies in the brain stem and hypothalmus of the frog (Rana temporaria) was investigated with the help of the histofluorescence technique of Falck and Hillarp ('62). At the level of the hypothalmus of this amphibian brain, catecholamine‐containing nerve cell bodies are found mainly within three areas of the periventricular gray substance, namely the peroptic recess organ, the paraventricular organ and the lateral recess region. On the other hand, most of the 5‐hydroxytryptamine (serotonin)‐containing nerve cell bodies of the brain stem of Rana temporaria appear to be concentrated within the midbrain tegmentum. This huge mesencephalic nerve cell collection can be subdivided into medial and lateral groups. More caudally, at the level of the isthmic tegmentum, another group of 5‐hydroxytryptamine‐containing perikarya located close to the midline, within the so‐called raphae region, is clearly outlined. The latter group of neurons extends caudally as far as the level of the medulla oblongata. In addition, a small group of catecholamine‐containing nerve cell bodies is also found in the ventromedial portion of the rostral midbrain tegmentum, whereas a few other catecholamine type neurons are scattered throughout the lower brain stem of the frog and more especially near the ependymal wall of the fourth ventricle. As a whole, the 5‐hydroxytryptamine‐containing neuronal systems of the brain stem of Rana temporaria are much more elaborated than the catecholamine neuronal systems of the same structure.
Electron microscopy of the esophageal ganglion complex of the gastropod pulmonate Triodopsis divesta. I. Ultrastructure of the epineurium
Authors: Dyer Robert F. , Cowden Ronald R. 
Published: February 2005

AbstractThe epineurium of the esophageal complex of the gastropod pulmonate Triodopsis divesta was examined by electron microscopy. The epineurium consists of two main regions: an inner dense fibrous region adjacent to the avascular neural tissue of the ganglion and an outer cellular region comprised of a variety of cell types embedded in a connective tissue matrix. The dense fibrous region contains smooth muscle cells and associated nerve processes and is invested on the neural side by thin processes of glial cells. The outer highly cellular region contains smooth muscle cells, nerve processes, wandering cells (amebocytes), globular cells, and myoepithelial cells comprising the walls of the vascular system. In addition, a cell type not previously identified in other gastropod epineuria is present. These cells resemble neurosecretory cells. The morphology and structural interrelationships of these various constituents are presented and the possible functions of individual cell types and the epineurium in general are discussed in relation to information available on other molluscs.
Sense organs on the antennal flagellum of two species of embioptera (Insecta)
Authors: Slifer Eleanor H. , Sekhon Sant S. 
Published: February 2005

AbstractFive different kinds of sense organs have been identified on the antennal flagellum of males of Ptilocerembia sp: (1) tactile hairs, (2) thick‐walled chemoreceptors, (3) chemoreceptors with thick walls and many pores, (4) thin‐walled chemoreceptors and (5) campaniform sense organs. The third type has not been reported previously for other species of insects and combines the characteristics of typical thick‐walled and thin‐walled chemoreceptors. The campaniform sense organs are situated in sets of three, 120° apart, on the periphery of the distal end of nearly every subsegment. They lie at the transition zone where the thicker cuticle of the subsegment changes to the thin membrane between subsegments.
Histogenesis of atretic ovarian follicles in a seasonally breeding bird
Authors: Erpino Michael J. 
Published: February 2005

AbstractHistologic examination of ovaries from a non‐migratory population of scrub jays (Aphelocoma coerulescens) disclosed a marked annual cycle in the incidence of atresia. Atretic follicles became more common as the nesting season progressed and were most abundant immediately after the cessation of breeding. Atresia involved a dissociation of granulosa cells and movement of these cells into the follicle. Subsequently, granulosa cells showed steatogenesis and ultimately disappeared simultaneously with the invasion of the follicle by ex‐thecal gland cells. The data suggest that the diverse histology of avian atretic follicles reflects different stages in the process of atresia rather than multiple origins. Ovarian stromal glands apparently arise both from ex‐thecal gland cells of atretic follicles and stromal connective tissue. A possible secretory role of atretic follicles is considered.
Heart Development in the Mexican Salamander, Ambystoma mexicanum. I. Gross anatomy, histology and histochemistry
Authors: Lemanski Larry F. 
Published: February 2005

AbstractGross anatomical, histological and histochemical studies of heart development in Mexican salamanders, Ambystoma mexicanum, are reported. Gross observation suggests that heart development in this urodele species is similar to other amphibians. Histological studies in early embryos show the ventromedially migrating sheets of precardiac mesoderm to be composed of two layers of cells. The right and left dorsal layers fuse and give rise to the myocardium, while the ventral layers form the pericardium. The endocardium arises from cells released by the leading edges of the migrating mesoderm mantles. In early myocardial cells, most of the proteins and carbohydrates are contained in yolk platelets; subsequently, these substances become distributed throughout the cytoplasmic matrixes. In early heart cells free lipid droplets are abundant but decline in size and number as development progresses. Concomitantly, there is an increase in bound lipids. Reticular fibers are detected in the endocardial‐myocardial spaces simultaneously with trabeculae formation. Collagen appears somewhat later in development.
Palatogenesis in hamster. II. Ultrastructural observations on the closure of palate
Authors: Chaudhry A. P. , Shah R. M. 
Published: February 2005

AbstractFormation of secondary palate in hamster was studied with electron microscopy. Prior to assuming horizontal position, the palatal shelves were covered by a two to three cell layer thick epithelium which was separated from the underlying mesenchyme by an intact basal lamina. Epithelial cells were attached to each other by desmosomes. Early hemidesmosomes could be identified as thickenings of the cytoplasmic membrane opposing the basal lamina. Epithelial cells, like other embryonic cells, contained only few organelles but were rich in polyribosomes. As the horizontal shelves approached each other towards the midline, lysosomes and tonofilaments appeared in the superficial and basal cells of the epithelia. Superficial cells showed degeneration and eventual lysis. Fusion of the opposing epithelia occurred between the deeper cells by means of newly formed desmosomes. The epithelial seam resulting from fusion of the epithelia was limited on each side by a continuous basal lamina. Its subsequent thining and eventual fragmentation resulted from the loss of cells by autophagy. There was no evidence of mesenchymal invasion of the epithelial seam. Mesenchymal macrophages appeared in the later stage of palatogenesis and were responsible for phagocytosis of cellular debris.Formation of the soft palate was basically similar to that of the secondary hard palate and occurred by fusion of the opposing shelves. Similarly, anterior closure of the palate occurred by fusion of the lower end of the nasal septum to the primary and secondary palates. Hyperplasia of the opposing epithelia, prior to their fusion, was often seen.It is suggested that formation of the palate occurs in predictable and coordinated fashion and that timely appearance of lysosomes causing lysis of intervening epithelia is of great significance in normal palatogenesis.
Scanning electron microscopy of scales from different body regions of three lizard species
Authors: Stewart Glenn R. , Daniel Ronald S. 
Published: February 2005

AbstractThe Oberhautchen of scales from the dorsal, parietal, and ventral regions of Sceloporus occidentalis (Iguanidae), Gerrhonotus multicarinatus (Anguinidae), and Anniella pulchra (Anniellidae) were examined with a scanning electron microscope. At low magnification, all scales of S. occidentalis exhibit well‐defined outlines of cells belonging to the Oberhautchen layer and the previously overlying clear layer. The dorsal and parietal cells of this species exhibit a minutely dentate Oberhautchen that forms tooth‐like spinules 0.2 to 0.5 μ long and arranged in irregular rows. Minute pits 0.1 to 0.3 μ in diameter characterize the Oberhautchen of a ventral scale.Cell outlines are not evident on the scales of G. multicarinatus. The Oberhautchen of dorsal and parietal scales of this species is prominently laminated. Laminae are less prominent on scales of the lateral fold, and no intrinsic surface structure is evident on a ventral scale. In contrast, the fossorial anguinomorph Anniella pulchra exhibits Oberhautchen surfaces with practically no intrinsic microornamentation. However, what appear to be outlines of Oberhautchen cells are visible on the dorsal and ventral scales.These observations suggest that modifications of Oberhautchen microornamentation may have evolved to reduce friction with the substrate or other scales. The lack of pronounced microornamentation of the Oberhautchen on some body scales may indicate that a complex interdigitation between clear layer and Oberhautchen cells is not essential to the sloughing process.
The blood system of the flabelligerid polychaete Flabelliderma commensalis (Moore)
Authors: Spies Robert B. 
Published: February 2005

AbstractThe blood system of the flabelligerid polychaete, Flabelliderma commensalis has been explored by dissection, light and electron microscopy and absorption spectrophotometry. The main longitudinal vessels are the dorsal, ventral, perineural, sub‐oesophageal, supra‐oesophageal and heart. Each segment has a segmental vessel which communicates with the dorsal vessel in thoracic setigers and the gut sinus in abdominal setigers. Branches of the segmental vessels in setigers 2–9 supply the gonads. A blood sinus envelopes most of the gut. Circulation is maintained by the pumping of the heart which immediately supplies blood to the supra‐oesophageal ganglion, the branchiae and the palps. These are paralleled by a system of collecting vessels. The sinus of the supra‐oesophageal ganglion receives a number of different axonal endings, some of which may be neurosecretory. The retroperitoneal vessels in their most developed form are composed of an intima, longitudinal and circular muscles and a peritoneum. The heart vessel contains a cardiac body whose cells appear to contain vacuoles of blood pigment. The blood pigment exhibits the absorption characteristics of a chlorocruorin with maxima at 438, 558 and 606 nm.
Microtubules and muscle attachment in the integument of the balanidae
Authors: Koulish Sasha 
Published: February 2005

AbstractAttachment of muscle of the integument was studied in two species of Balanidae, Balanus balanoides and B. improvisus with electron microscopy. Specilalized epithelial cells (tendon cells) intervene between the muscle and overlying cuticle. An extensive desmosome‐like junction exists between these two tissues. The tendon cell contains huge amounts of microtubules aligned parallel to the long axis of the inserting muscle. Tension exerted by contracting muscles is conveyed to the chitinous exoskeleton via the specially organized tendon cells and the extensive myo‐tendinal cell junctions.
Preliminary investigation of variations in tooth replacement in adult Necturus maculosus
Authors: Miller William A. , Rowe Dorothy J. 
Published: February 2005

AbstractAlthough there are a number of studies on tooth replacement patterns in lower vertebrates, most do not indicate whether this process is continuous throughout the year or is affected by either breeding or seasonal cycles. We have surveyed the replacement patterns found in living and specifically killed Necturus maculosus (Amphibia: Proteidae) to determine the nature of their variation throughout the year prior to investigating possible controlling mechanisms of the formation and eruption of amphibian teeth. Some animals (34), kept in a large outside tank, were killed at monthly intervals and their tooth‐bearing bones radiographed using a modification of the technique previously described (Miller and Radnor, '70). Other animals (9), kept at 4°C, were anesthetized with tricaine methanesulphonate (M.S. 222), and wax impressions taken with beading (carding) wax of the functioning teeth at regular intervals. Animals examined in the late spring and summer (25) showed no signs of active tooth replacement. Small replacement teeth visible beneath each functioning tooth enlarged only slightly throughout the summer. In early and late fall some functioning teeth were lost and replacement teeth grew and erupted to replace them. Replacement patterns were very irregular and classical alternate form rarely seen. In a number of animals the replacement series was formed from every third tooth. Animals kept constantly at 4°C showed no replacement phenomena. Patterns varied between the different bones of the jaws and did not support the Zahnreihe concept of Edmund ('60).
Structure and function of the olfactory apparatus in the fresh‐water carp, Labeo rohita ham. buch.
Authors: Ojha P. P. , Kapoor A. S. 
Published: February 2005

AbstractThe oval olfactory rosette of the carp Labeo rohita belongs to Burne's ('09) rosette column one or to Bateson's (1889) rosette type three. The total olfactory area of the fish is greater than its total retinal area; however, it has been classified with Teichmann's ('54) group of eye‐nose fishes. Each olfactory chamber communicates with an anterior, ventral accessory sac; in spite of Burne's ('09) observation that accessory sacs are absent in carps. Movements of the jaw bones dilate and compress the accessory sac. Water is drawn in through the posterior opening (and not through the anterior as suggested by Liermann, '33, and Johnson and Brown, '62) and also expelled through it when the mouth opens and closes for normal respiratory function. Hence, the accessory sac does not draw water across the olfactory rosette through the anterior opening. At intervals, the fish opens its mouth full and wide and draws water into the chamber through the anterior opening as well.
Stereotaxic map of the muscle fibers in the indirect flight muscles of Drosophila melanogaster
Authors: Levine Jon D. , Hughes Malcolm 
Published: February 2005

AbstractIt is possible to monitor the electrical activity of the motor neurons of Drosophila by recording the electrical activity of the muscle fibers. We have found that it is possible to specify the location of the subcuticular terminations and to describe the orientation within the thorax for the individual muscle fibers, because of the large size of the fibers and because the surface anatomy of Drosophila is known in detail. A map has been made to indicate the location of the muscle fibers with respect to superficial landmarks. The importance of the stereotaxic map for physiological studies is discussed.
The role of cell death during morphogenesis of the mammalian eye
Authors: Silver J. , Hughes A. F. W. 
Published: February 2005

AbstractSerial sections of embryonic rat eyes were stained with hematoxylin and eosin, quantified (by counting pycnotic and viable nuclei), reproduced by camera lucida on wax plates, and moulded into reconstructions in order to study the normal progression of cellular death during morphogenesis. At least nine distinct necrotic loci (A through I) can be distinguished. Immediately following contact between the retina and surface ectoderm (day 11) degenerating cells were observed in (A) the ventral extent of the optic vesicle, beginning in the mid‐retinal primordium and continuing ventrally in the optic stalk, (B) in the rostral optic stalk base, and (C) in the surface ectoderm encircling the early lens placode. No degeneration was observed in the dorsal half of the presumptive retina, in the entire pigment epithelium, or in the lens placode proper. During day 11.5 the lens placode thickens and forms a degenerating locus (D) in its ventral portion opposite the underlying pycnotic zone in the retina (A). During day 12 the ventral pycnotic zone (A) divides into two subunits (A1 and A2). Invagination of the lens displaces its marginal and ventral components (C and D) so that they come to occupy the lens pore area and presumptive corneal epithelium. Simultaneous invagination of the retinal rudiment juxtaposes the pigment epithelium which concurrently forms a necrotic area (E) adjacent ventrally to that in the retina (A1). Degeneration appears in the caudal optic stalk (I). The density of viable cells decreases adjacent to pycnotic areas in the retina and pigment epithelium and increases within these death centers. During day 13 the optic fissure forms within the subunits of the ventral pycnotic zone (A1 and A2). Degenerations are seen in the dorsal optic stalk (F) and in the walls of the optic fissure (G and H). Throughout these stages necrosis appears only in those portions of the eye rudiment where invagination is either retarded or completely absent.In part, these observations suggest that cell death serves (1) to retard or inhibit invagination within death centers, (2) to integrate the series of invaginations which mould the dorsal optic cup and optic fissure, (3) to assist formation of the pigment epithelium monolayer, and (4) to orient the lens vesicle within the eye cup. The spatio‐temporal relationship between necrotic loci suggests that pycnotic cells in the retina may influence their production in the lens and pigment epithelium. Preliminary observations on the mouse, pig, and human substantiate those on the rat.
Some structural and cytochemical observations on the axial filament complex of lung‐fluke spermatozoa
Authors: Burton Paul R. 
Published: February 2005

AbstractAs seen in transverse section, doublet elements of the axial unit of spermatozoa of Haematolocchus medioplexus, a frog lung‐fluke, possess walls made up of protofibrillar subunits 50–60 Å in diameter. The partition between A and B members of a doublet element often show extra protofibrils which may partially occlude the “lumen” of the A tubule. Each A tubule possesses outer and inner lateral arms which repeat at longitudinal intervals of about 215 Å and which appear to be structurally dissimilar; the outer arm is expanded at its free end and the inner arm often connects to the B tubule of the adjacent doublet element. Regularly‐spaced radial links connect the central sheath of an inner core complex to the A tubules of the peripheral doublet elements. Tests for magnesium‐activated ATPase activity provide evidence that the enzyme is associated with the surfaces of doublet elements and the surface of the central sheath. Finally, study of an axial unit which developed in an abnormal manner suggests that normal differentiation of an axial unit may depend on the elaboration of a core complex and radial links.