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  • Articles  (2,042)
  • Articles: DFG German National Licenses  (2,042)
  • Life and Medical Sciences  (2,042)
  • 1985-1989  (1,345)
  • 1980-1984  (697)
  • 1925-1929
  • 1988  (1,345)
  • 1983  (697)
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  • Articles  (2,042)
Source
  • Articles: DFG German National Licenses  (2,042)
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Years
  • 1985-1989  (1,345)
  • 1980-1984  (697)
  • 1925-1929
Year
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 175 (1983), S. 1-16 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Six types of hemocytes were identified in fifth instars of the Indian meal moth, Plodia interpunctella. The morphology of these cells was characterized by phase contrast and electron microscopy, with Sudan black B, Giemsa, Janus green B, and periodic acid-Schiff staining. Reaction of the hemocytes with seven fluorescing lectin conjugates revealed distinctive binding patterns by their plasma and nuclear membranes and cytoplasmic inclusions. A direct line of descent from prohemocytes to plasmatocytes to granulocytes is suggested from these morphological observations.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 175 (1983), S. 33-56 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: New fossils of the rare Oligocene mammals Xenocranium and Epoicotherium add information on their skulls and provide the first information on their postcranial skeletons. These epoicotheres, the latest surviving palaeanodonts, have numerous fossorial adaptations and must have been predominantly subterranean. Their skeletal specializations are similar to, and equal or surpass in degree of development, those of most living fossorial mammals.Principal modifications of the skull are the expanded, domed occiput with broad lambdoid crests, hypertrophy of the malleus-incus and related changes in other ear components, reduced eyes, and (in Xenocranium) a flaring, upturned, spatulate snout. The neck was strengthened by synostosis of the 2nd through 5th cervical vertebrae. The forelimb elements have exaggerated crests, processes, and fossae for muscles used in digging or in stabilizing certain joints. The scapula has a high, stout spine with bifid acromion, a “secondary spine,” and an expanded postscapular fossa for attachment of the teres major muscle. The humerus has an elongate pectoral crest, large lesser tuberosity, long entepicondyle, and large hooklike supinator crest. The enormous incurved olecranon process of the ulna provided insertion for the massive triceps and origin for the carpal and digital flexors, and the latter gained mechanical advantage by incorporating in its tendon a large carpal sesamoid. In the greatly shortened hand, digit three is largest, with its metacarpal and proximal phalanx fused and its claw-bearing ungual-phalanx very large.These traits indicate that Xenocranium and Epoicotherium were among the most specialized “rapid-scratch” diggers ever to evolve. Their remarkable convergence to chrysochlorids reflects a similar mode of digging, with extensive use of the snout for loosening and lifting soil when making shallow foraging burrows. For deeper burrowing, the forelimbs probably loosened the soil while the rear limbs moved it behind. Like many extant subterranean mammals, Xenocranium and Epoicotherium were essentially sightless, but they were specialized for low frequency sound reception. Their extinction may have been due to a combination of environmental change and competition with other fossorial animals, such as proscalopine insectivores and rhineurid amphisbaenians.
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  • 3
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 175 (1983), S. 119-130 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the sprawling gait of Varanus exanthematicus, the bicondylar distal humerus requires both the radius and ulna to rotate in the same direction. The joints between the radius and radiale and between the ulna and ulnare and pisiform accomodate these specific rotations. A ligament system between radius, ulna, radiale, and ulnare causes the radius and ulna to approximate one another during external rotation of the forearm. This approximation is conveyed distally resulting in a narrowing of the hand during external rotation of radius and ulna or during pronation of the free hand. The significance of these and related linkages is discussed.
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  • 4
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 175 (1983), S. 57-64 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The overall anatomy of Neodasys as well as data for hemoglobin-containing cells are described. Hemoglobin-containing cells are shown to be mesodermal specializations constituting approximately 14% of the animal's total body volume (4.87 ± 104 μl). These globular cells (10-14 μm) are situated in two longitudinal rows, each dorsolateral to the straight gut. Branches from the cells enwrap perikarya of muscle and nerve cells whose mitochondria are found just below their respective plasmalemmata in intimate association with the hemoglobin-containing cells. The ground substance of the cytoplasm and nucleoplasm of these nearly organelle-free cells is extremely electron-dense and is presumed to represent the hemoglobin molecules. Locomotion analyses indicate that the cells can undergo a threefold change in linear dimension in 0.25 seconds, raising the possibility of convective mixing in these cells. Structural and ultrastructural comparisons with similar cells in adults of other species of Gastrotricha indicate that the hemoglobin-containing cells of Neodasys may be homologous to the socalled Y cells of other species, some of which contain myofilaments. A muscle-cell origin is considered for the evolution of hemoglobin-containing cells of Neodasys.
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  • 5
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 175 (1983), S. 91-100 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The digestive tract of the freshwater amphipod Hyalella azteca is a straight but differentiated tube consisting of foregut, midgut, and hindgut divisions. The foregut is subdivided into a tubular esophagus, a cardiac stomach, and a pyloric stomach. The cuticular lining of the cardiac stomach is elaborated into a set of food-crushing plates and ossicles, the gastric mill, while the pyloric cuticle forms a complex straining and pressing mechanism. Nine caeca arise from the midgut, seven anteriorly and two posteriorly. Four of the anterior caeca, the hepatopancreatic caeca, are believed to be the primary sites of digestion and absorption. The remaining caeca may be absorptive, secretory, or both. The much-folded hindgut wall is capable of great distention by extrinsic muscle action for water intake to aid in flushing fecal material out of the anus; such action also may stimulate antiperistalsis by intrinsic rectal muscles.
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  • 6
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 175 (1983), S. 131-142 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The proximal, intermediate, and distal convoluted tubules of the neprhon of Podarcis (= Lacerta) taurica were examined by electron microscopy. Proximal tubule cells have large, apical cytoplasmic protrusions and microvilli interpreted to function in urate secretion. Adjacent cells are bound apically by tight junctions and desmosomes but interdigitate in their basal region. This situation is repeated in the other tubules with significant differences in intercellular space width. The basal surfaces bear numerous cytoplasmic processes. The intermediate tubule has proximal and distal segments each with dark, ciliated, and light cells, the cuboidal dark cells with dense cytoplasm constituting the main bulk of the wall. As the cells of the proximal and distal segments resemble those of the proximal and distal convoluted tubules, respectively, the intermediate tubule is considered as a transition region. The ciliated cell body has two broad processes extending from the lumen, one to the basement membrane and one to a foot process of a light cell. The light cell is surrounded by dark and ciliated cells. It does not reach the lumen, but contacts the basement membrane through a process running below a ciliated cell to form a mushroom-shaped structure in tubule cross-section, the light cell process forming the stalk and a ciliated cell the cap. The cilia probably propel the glomerular filtrate towards the distal convoluted tubule. This latter tubule has initial, middle, and terminal zones, all nonciliated but with different lumen widths and cell shapes.
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  • 7
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 175 (1983), S. 153-169 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ultrastructure of the stylets produced by nine species of nemerteans has been examined by scanning electron microscopy (S.E.M.) and polarized light microscopy. Stylets are solid, nail-shaped structures that typically reach lengths of 50-200 μm. Each stylet is composed of a centrally located organic matrix surrounded by an inorganic cortex that contains calcium and phosphorus. When viewed at high magnifications, fine granules can be seen throughout the organic matrix, and the cortex appears to be composed of densely packed homo-geneous material. Fractured specimens and whole matrices isolated from decalcified stylets reveal a close correspondence between the shape of the organic matrix and that of the surrounding cortex. This similarity in morphology suggests that the organic matrix serves as a template during calcification of the stylet. The fact that abundant material can be seen in the core of incinerated stylets, and in the central region of stylets that had been soaked for several hours in sodium hypochlorite, supports the hypothesis that the organic matrix is also highly calcified. Polarization microscopy of nemertean stylets indicates that they are composed of a crystalline, rather than amorphous, form of calcium phosphate. The probable organization of the calcium phosphate crystals is discussed.
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  • 8
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 175 (1983), S. 293-306 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The present study traces corneal morphogenesis in a reptile, the lizard Calotes versicolor, from the lens placode stage (stage 24) until hatching (stage 42), and in the adult. The corneal epithelium separates from the lens placode as a double layer of peridermal and basal cells and remains bilayered throughout development and in the adult. Between stages 32- and 33+, the corneal epithelium is apposed to the lens, and limbic mesodermal cells migrate between the basement membrane of the epithelium and the lens capsule to form a monolayered corneal endothelium. Soon thereafter a matrix of amorphous ground substance and fine collagen fibrils, the presumptive stroma, is seen between the epithelium and the endothelium. Just before stage 34 a new set of limbic mesodermal cells, the keratocytes, migrate into the presumptive stroma. Migrating limbic mesodermal cells, both endothelial cells and keratocytes, use the basement membrane of the epithelium as substratum. Keratocytes may form up to six cell layers at stage 37, but in the adult stroma they form only one or two cell layers. The keratocytes sysnthesize collagen, which aggregates as fibrils and fibers organized in lamellae. The lamellae become condensed as dense collagen layers subepithelially or become compactly organized into a feltwork structure in the rest of the stroma. The basement membrane of the endothelium is always thin. Thickness of the entire cornea increases up to stage 38 and decreases thereafter until stage 41. In the adult the cornea is again nearly as thick as at stage 38.
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  • 9
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 176 (1983), S. 181-196 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Measurements have been made of those changes which lead to increases in the surface area of the intestine during the metamorphosis of three species of lampreys. Although the intestine of the Southern Hemisphere lamprey, Geotria australis, increases in length by 1.13 times and in diameter by 1.12 times, the main factor influencing the 5.71 times increase in surface area is the development of longitudinal folds. The contribution of the typhlosole to the internal perimeter of the intestine is less in most life cycle stages of G. australis than in Lampetra spp. The changes in the various intestinal measurements of the nonparasitic species L. planeri parallel those of the presumed ancestral parasitic species, L. fluviatilis, during the first six stages of metamorphosis. However, the longitudinal folds, but not the typhlosole, subsequently start regressing in L. planeri just after the time when the rate of gonadal development increases markedly. An account is also given of the pattern of fold formation and the development of the typhlosolar vein in G. australis.
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  • 10
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 176 (1983), S. 247-247 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: No Abstracts.
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  • 11
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 176 (1983) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 12
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The formation of the alimentary canal, nervous system, and of other ectodermal derivatives in the embryo of the primitive moth, Neomicropteryx nipponensis Issiki, is described. The stomodaeum is formed from an invagination in the medioposterior portion of the protocephalon. The proctodaeum arises as an extension of the amnioproctodaeal cavity. The midgut epithelium orginates from anterior and posterior rudiments in blind ends of the stomodaeum and proctodaeum. The decondary dorsal organ is formed in developing midgut. The development of the brain is typical of insects. The ventral nerve cord originates in large part from neuroblasts arising in 3 gnathal, 3 thoracic, and 11 abdominal segments. Intrasegmental median cord cells probably differentiate into both ganglion cells and glial elements of the ventral nerve cord; intersegmental cells appear not to participate in the formation of the nervous system. The stomatogastric nervous system develops from three evaginations in the dorsal wall of the stomodaeum, and consists of the frontal, hypocerebral, and ventricular ganglia, the recurrent nerve, and corpora cardiaca. Five stemmata arise from the epidermis on each side of the head. Five pairs of ectodermal invaginations are formed in the cephalognathal region to produce the tentorium, mandibular apodemes, corpora allata, and silk glands. Prothoracic glands orginate in the prothorax. Mesothoracic spiracles shift anteriorly to the prothorax during development. Oenocytes arise in the first seven abdominal segments. Invaginated pleuropodia are formed in the first abdominal segment.
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  • 13
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 178 (1983), S. 23-35 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ultrastructural observations and glyoxilic acid-induced fluorescence of catecholamines indicate that tracts of axons lie at the base of the ciliary bands and run throughout their length in bipinnaria and brachiolaria larvae of Pisaster ochraceus. Two types of nerve cells occur at regular intervals within the ciliary bands. Type I nerve cells are associated with the axonal tracts, and type II nerve cells, which are ciliated, occur along the edge of the ciliary bands. Two prominent ganglia, which appear as accumulations of nerve cells and neuropile, occur on the lower lip of the larval mouth. Smaller ganglia occur irregularly throughout the ciliary band. Synapses were never clearly identified and were assumed to be unspecialized. Nervous tissues were also found associated with the esophageal muscles, the attachment organ, and the larval arms. Organization of the nervous system and its association with effectors suggest it controls swimming and feeding. Several similarities exist between the nervous systems of larval asteroids, larval echinoids, and adult echinoderms.
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  • 14
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 178 (1983), S. 1-21 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The gross morphology and electrical activity of the muscles of the pharyngeal apparatus of centrarchid sunfishes (Lepomis) are analyzed within a monophyletic clade containing species specialized for snail-eating. Outgroup comparisons of both structure and activity patterns of muscles permit examination of the relationship between specialized diet and function of the trophic apparatus. In most sunfish species, electrical activity in the pharyngocleithralis internus muscle significantly overlaps that in the retractor dorsalis muscle during pharyngeal transport, indicating that the upper and lower pharyngeal jaws retract together. Activity in the pharyngohyoideus, levatores externi, and levator posterior also significantly overlaps activity of the retractor dorsalis.Snail-eating is associated with derived morphological, behavioral, and functional features. The shell is crushed before pharyngeal transport, correlated with extensive overlap in activity periods of muscles. One species, Lepomis microlophus, possesses a highly stereotyped neuromuscular repertoire that does not vary with prey type. All prey, even fish and worms, are subjected to crushing. Lepomis gibbosus exhibits the crushing pattern of muscle activity only when feeding on snails. L. microlophus has a hypertrophied levator posterior muscle, but the lines of action of the pharyngeal muscles are similar to the primitive condition. Pharyngeal transport in this species is unique in that activity of the pharyngocleithralis internus alternates with that of the retractor dorsalis.In sunfishes, alterations in the central control of peripheral structures have produced major changes in the sequence in which homologous components of the structural network are activated.
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  • 15
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 178 (1983), S. 77-87 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The scent apparatus of male Eldana saccharina is a glandular complex on the costal area of the forewing. It consists of two parts; glandular complex 1 is composed of five kinds of cells (epidermal cells, scale cells, glandular cells, supporting cells, duct cells); glandular complex 2 also shows five types of cells (epidermal cells, scale cells, glandular cells, duct cells, trichogen cells). The secretory products of the two parts are discharged into separate ducts which converge before opening onto the lower side of the wing. The male also has two prominent hair-pencils borne on the coremata and large secretory trichogen cells on the genital valves. Each of these exocrine gland components plays an important part in formation of the chemically complex pheromones utilized in the precopulatory behavior of the male.
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  • 16
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    Journal of Morphology 195 (1988), S. 45-58 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distribution of neutral red staining peripheral cell bodies along the nerve trunks of the thoracic median nervous system of the locust, Schistocerca gregaria, is described. Backfilling of the cells with cobalt chloride solution reveals that they are neurones with characteristic axonal processes that terminate in the neurohaemal areas of the median nerve. The neurones react with the dye acridine orange, indicating their neurosecretory nature. This is confirmed by their ultrastructural appearance at the electron microscope level. The distribution and staining properties of the cells are compared with those of peripheral neurones from other insects and the nature of their neurosecretory product is discussed.
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  • 17
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    New York, NY : Wiley-Blackwell
    Journal of Morphology 195 (1988), S. 83-93 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Numerous functional ergatoid replacement reproductives were found in one colony of Nasutitermes columbicus in Panama. Their morphology was mainly workerlike, although several imaginal characters such as the compound eyes and variable wing buds were more or less developed. The sex organs were fully mature and the fat body of the females, not of the males, was of the “royal” type. The development of the eyes was not accompanied by the differentiation of the optic lobes of the brain, nor was the presence of wing buds correlated with a development of the wing muscles.
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  • 18
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    Journal of Morphology 195 (1988), S. 123-140 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The surface morphology of the anterior-to-posterior sequence of segment formation in embryos of a viviparous neotropical onychophoran and aspects of post-placental development seen using scanning electron microscopy are described. When all the segments have formed and the walking legs have completed their elongation, the body surface becomes covered with an embryonic cuticle that does not exhibit the hydrofuge properties seen in the adult cuticle. As soon as the walking legs have reached their full length, barbed projections are formed at their distal extremities. These projections are extensions of single cells and are covered by the embryonic cuticle. Transmission electron microscopy reveals that the cells at the distal ends of the legs and their projections have many pinocytotic vesicles at their surfaces. The cytoplasm of these cells and their projections is rich in mitochondria, rough endoplasmic reticulum, glycogen, and granules of storage material. There are minor differences in the surface morphology of the projections found at the ends of the walking legs in embryos of Peripatus acacioi and those of Peripatus biolleyi. The projections and the embryonic cuticle persist thoughout postplacental development. The role of the projections in the uptake of material by the embryo from the uterus is discussed and the possible phylogenetic significance of these projections is suggested.
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  • 19
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    Journal of Morphology 195 (1988) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 20
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    Journal of Morphology 195 (1988), S. 257-303 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The vertebral centra of Hiodon, Elops, and Albula are direct perichordal ossifications (autocentra) which enclose the arcocentra as in Amia. An inner ring of ovoid cells forms in late ontogeny from the intervertebral space inside the autocentrum. The chordacentrum is reduced or completely absent in centra of adult Elops, whereas it forms an important portion of the centra in adult Hiodon. The posterior portion of the compound ural centrum 3+4+5 is partially (Hiodon) or fully formed by the chordacentrum (Elops, Albula). The haemal arches and hypurals are fused medially by cartilage or bone trabecles of the arcocentrum with the centra, even though they appear autogenous in lateral view in Elops and Albula. The composition of the caudal skeleton of fossil teleosts and the ontogeny of that of Hiodon, Elops, and Albula corroborate a one-to-one relationship of ural centra with these dorsal and ventral elements. The first epural (epural 1) of Elops relates to ural centrum 1, whereas the first epural (epural 2) of Hiodon and Albula relates to ural centrum 2. In Albula, the first ural centrum is formed by ural centrum 2 only. With 4 uroneurals Hiodon has the highest number within recent teleosts. Juvenile specimens of Hiodon have eight, the highest number of hypurals within recent teleosts; this is the primitive condition by comparison with other teleosts and pholidophorids. Reduction of elements in the caudal skeleton is an advanced feature as seen within elopomorphs from Elops to Albula. Such reductions and fusions occur in osteoglossomorphs also, but the lack of epurals and uroneurals separates most osteoglossomorphs (except Hiodon) from all other teleosts.
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  • 21
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    Journal of Morphology 195 (1988), S. 327-344 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fertilized egg and the two-cell stage and four-cell stage of the marsupial Antechinus stuartii were studied by transmission electron microscopy. The features that make the fertilized egg of Antechinus stuartii different from those of any eutherian mammal are (1) the presence of a shell and (2) the relatively large quantity and polarized distribution of cytoplasmic inclusions, including lipid, protein yolk bodies, and protein fibers. Mitochondria and vesicles of smooth endoplasmic reticulum are also polarized in distribution. Early cleavage differs from that of eutherians in several ways: (1) it occurs in the uterus; (2) there is extrusion of a large, single, membrane-bound yolk mass at first cleavage; and (3) blastomeres become separated after the second cleavage division and thus do not adhere by cell-to-cell contacts. Prior to the second division, blastomeres are connected to each other by remnants of the midbody and to the yolk mass by remnants of a cytoplasmic bridge. The yolk mass after extrusion is surrounded by plasma membrane and contains inclusions of lipid, protein yolk bodies, and fibers, as well as mitochondria and smooth endoplasmic reticulum. The blastomeres of the two-cell and four-cell stages also show intracellular polarization in the distribution of retained inclusions and organelles. Vesicles developing at the periphery of blastomeres and discharging their contents extracellularly increase in size and number from the fertilized egg to the four-cell stage. The discharged contents may be implicated in early development of the blastula cavity.
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  • 22
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    Journal of Morphology 196 (1988), S. 15-22 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Morphology of branchial chloride cells in the freshwater teleosts Plecoglossus altivelis, Cyprinus carpio, and Oreochromis mossambicus was studied by light and transmission electron microscopy. The chloride cell has an apical membrane directly in contact with the outer medium. Generally, two or more neighboring chloride cells share an apical pit, forming a multicellular complex. The chloride cells form a multicellular complex in which cells differ in cytoplasmic electron density, development of tubular system, and in cell size. Chloride cells are linked by junctions which are shallower than the tight junctions that occur between neighboring pavement cells or between pavement and chloride cells. Multicellular complexes of chloride cells create additional paracellular pathways marked apically by the shallower junctions. Since junctional structure affects transepithelial permeability, development of multicellular complexes of chloride cells in freshwater fishes may be related to the transport of some substances as in the gills of marine fishes.
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  • 23
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    Journal of Morphology 196 (1988), S. 23-31 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The nerve pathways in the praesoma are described for the first time for a member of the genus Octospinifer. Eleven nerves, five paired, and one single, are traced from the cerebral ganglion to their associations with the musculature of the body wall, neck sense organs, and the musculature of the proboscis wall and the invertor muscles of the proboscis. The structure and location of the Stützzelle (support cell) and its association with the neck sense organs are described. A comparison with the nervous system in the praesoma of Noechinorhynchus and Paulisentis is discussed.
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    Journal of Morphology 196 (1988) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 25
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    Journal of Morphology 196 (1988), S. 157-171 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology of the tongue of agamid lizards is reviewed and discussed in the context of its functional and phylogenetic significance. It is shown that in several features, including the development of the central musculature of the tongue into a ring muscle and the presence of a genioglossus internus muscle in adults, the tongue in most agamids is derived relative to that in other squamates. In some features, such as the vertical connective tissue septa, agamids share primitive features with Sphenodon. Some conditions found in agamids are also found in anoline iguanids. Two genera, Uromastyx and Leiolepis, differ significantly from other agamids in intrinsic tongue musculature.The functional significance of the unique tongue morphology is that agamids utilize a different mechanism of tongue protrusion from that of other lizards. This mechanism involves the production of force against the lingual process, leading to an anterior slide of the tongue, and is detailed in this paper. Finally, I discuss the mechanical basis for the transformation series of tongue protrusion mechanisms from agamids to chamaeleonids. It is suggested that the mechanism of tongue protrusion in chamaeleonids is not unique, but is a highly derived state of the condition found in agamids.
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    Journal of Morphology 196 (1988), S. 187-193 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fine structure of the Malpighian tubules (Mts) and rectal sac (rs) is described in the larval tick Ornithodoros (Pavlovskyella) erraticus before and after feeding up to molting. Mts consist of structurally different pyramidal and cuboidal cells along the entire length of the tubule. In unfed ticks, the two types of cell are characterized by apical microvilli and a few basal membrane infoldings. The abundant pyramidal cells contain glycogen particles, lipid droplets, lysosomelike structures, and rickettsialike microorganisms. After feeding but before molting, pyramidal cells loose glycogen particles and become very dense and dramatically reduced in size. These cells are possibly involved in the formation of guanine crystalloids as an excretory product. In contrast, cuboidal cells, filled with glycogen particles, free ribosomes, and mitochondria in unfed larvae, grow steadily after feeding; their cytoplasm becomes rich in lipid droplets in addition to showing an increase in glycogen particles. Lipid and glycogen could be the source of energy required for water and ion reabsoprtion in which cuboidal cells are probably involved.The paired-lobe rs consists of one type of cuboidal cells with basal membrane infoldings and a brush-border microvilli covered by a fuzzy coat of glycocalyx. These cells grow rapidly after feeding; they have functional features indicating extensive, selective reabsorption of essential components from excretory products.
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  • 27
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    Journal of Morphology 196 (1988), S. 253-282 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The peritrophic membrane of Drosophila melanogaster consists of four layers, each associated with a specific region of the folded epithelial lining of the cardia. The epithelium is adapted to produce this multilaminar peritrophic membrane by bringing together several regions of foregut and midgut, each characterized by a distinctively differentiated cell type. The very thin, electron-dense inner layer of the peritrophic membrane originates adjacent to the cuticular surface of the stomadeal valve and so appears to require some contribution by the underlying foregut cells. These foregut cells are characterized by dense concentrations of glycogen, extensive arrays of smooth endoplasmic reticulum, and pleated apical plasma membranes. The second and thickest layer of the peritrophic membrane coalesces from amorphous, periodic acid-Schiff-positive material between the microvilli of midgut cells in the neck of the valve. The third layer of the peritrophic membrane is composed of fine electron-dense granules associated with the tall midgut cells of the outer cardia wall. These columnar cells are characterized by cytoplasm filled with extensive rough endoplasmic reticulum and numerous Golgi bodies and by an apical projection filled with secretory vesicles and covered by microvilli. The fourth, outer layer of the peritrophic membrane originates over the brush border of the cuboidal midgut cells, which connect the cardia with the ventriculus.
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    Journal of Morphology 196 (1988), S. 333-343 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The seminal receptacle of Paragonimus ohirai contains not only mature spermatozoa, but also atypical and degenerate ones, suggesting that abnormal spermatozoa are retained in this organ. The spermatozoon is of a parallel biflagellar type with cortical microtubules, consisting of the anterior region, first mitochondrial region, intermediate (amitochondrial) region, second mitochondrial region, posterior nuclear region (PNR) and tail region (TR). The first third of the spermatozoon exhibits typical undulatory movement, while the middle part shows vibratory movement. At the area between head and midsections (H-M area) the peripheral doublets of axonemes are interrupted, and the external ornamentation is distributed widely around this portion. Throughout the immotile PNR and TR, the axonemes lack the dynein arms of their peripheral doublets. H-M, PNR, and TR ultrastructural characteristics are specific in P. ohirai spermatozoon and seem to be closely related to its pattern of movement.
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    Journal of Morphology 196 (1988), S. 119-126 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In uloborid spiders, eye loss is accompanied by increased visual angles, optical material investment, and potential visual acuity of the retained eyes. Relative to carapace volume, the six-eyed Hyptiotes cavatus and two four-eyed Miagrammopes species have greater retinal hemisphere areas and lens volumes than do the eight-eyed uloborids Waitkera waitkerensis, Uloborus glomosus, and Octonoba sinensis. In Waitkera, in which the eyes have little visual overlap, and in Miagrammopes, in which eye loss simplifies the spiders' patterns of visual overlap, increased retinal cell density enhances potential visual acuity. However, this occurs at the expense of potential retinal cell sensitivity.
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    Journal of Morphology 196 (1988), S. 173-185 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Intercellular bridges joining cells contained in cysts of Chortophaga viridifasciata testes were studied with light and electron microscopy. Preparations consisted of expressed whole cells (living, or fixed and stained) as well as sections. The secondary spermatogonia of each cyst are joined centrally by persisting fused interzonal bodies (fusomes) of incompletely cleaved cells. Shifts in cell orientation during anaphase are apparently responsible for central as opposed to chain linkage of cells. In the primary spermatocytes, the central fusome is replaced by a chain linkage, apparently resulting from the breakdown of the fusome into its original interzonal body components. Intercellular bridges are also present in spermatids, but there is no evidence to indicate the time of their formation (in the immediately preceding meiotic divisions or in the secondary spermatogonial divisions). The function of the compact centrally situated fusome in the secondary spermatogonial cyst is discussed as it relates to synchrony, number of cell divisions, spermatodesm formation, and fertility.
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    Journal of Morphology 196 (1988), S. 205-216 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Using laboratory-grown colonies of Plumatella emarginata, the formation of the floatoblast and the sessoblast was studied. Both types of statoblast develop in the funiculus. Toward the termination of development, the floatoblast secretes a gas and the float chambers are filled with the gas in about 20-30 minutes. The floatoblast thus complete is separated from the funiculus. Until early epidermal-disc-stage, distinction between a floatoblast and a sessoblast is impossible at least morphologically. Toward the late epidermal-disc stage, a future sessoblast becomes larger than a future floatoblast and attaches by its cystigenic side to the cystid. Very often it initially attaches to a lateral wall, then migrates to the basal wall of the cystid. Both the attachment to and the migration along the cystid wall are attained by peritoneal cells covering the sessoblast, specifically by those in the marginal zone of the cystigenic side. The sessoblast is separated from the funiculus precociously, shortly after attachment to the cystid. Then, it produces the capsule, followed by the formation of both the lamella, a homologue of the float in the floatoblast, and the attaching apparatus.Almost all polypides produce floatoblasts (up to 17 in number), but only a small portion of them produce both floatoblasts and sessoblasts. The number of sessoblasts produced by a single polypide is usually not more than 3 but occasionally reaches up to 6. When multiple sessoblasts are formed by a polypide, they are as a rule derived from primordia located adjacently on the funiculus, accordingly successively in a short period, but their arrangement on the basal wall of the cystid does not always correspond to that on the funiculus. Sessoblast formation is never associated with the death of the mother polypide. Ancestrulae derived from statoblasts never produce mature statoblasts, though may undergo gametogenesis. Several mosaic statoblasts consisting of floatoblast- and sessoblast-portions were found in some species of the Plumatellidae. A primordium of the statoblast seems to have a dual ability of differentiating into either a floatoblast or a sessoblast; but little has been known about the mechanism or factors controlling the formation of these two types of statoblasts.
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    Journal of Morphology 196 (1988), S. 321-332 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The giant anterior salivary gland cells from the large mammalian blood-sucking, glossiphoniid leech, Haementeria ghilianii, can be subdivided into three morphologically and functionally distinct regions: (1) a soma, responsible for the synthesis and storage of secretory products; (2) a long cell process, responsible for the storage and intracellular transport of the secretory vesicles; and (3) the site of exocytosis at the process terminal. The giant somata are densely packed with secretory vesicles. Deep plasmalemmal invaginations invade the soma and form an extensive system of extracellular lacunae. The rough endoplasmic reticulum (ER) and the Golgi apparatus are organized in the cell periphery, near the highly branched nucleus, and along the lacunae. The somata taper into long processes extending over several centimeters to the proboscis tip. These contain secretory vesicles through their whole length. In the process periphery, the vesicles are completely ensheathed by a concentric subplasmalemmal smooth ER cisterna. This originates deeply within the soma and extends through the whole cell process to its terminal. The ER provides support for up to several hundred longitudinally oriented microtubules. Secretion occurs at the very tip of the cell processes, each of which terminates at the proboscis tip at the base of a cuticular pore.We found synapses close to the sites of exocytosis, providing morphological evidence for neuronal control of secretion.
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    Journal of Morphology 196 (1988), S. 353-362 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two fast-twitch fiber types are histochemically identified in the primary flight muscles of Artibeus jamaicensis. These are classified as type IIa and IIb according to an acid-preincubation staining protocol for myosin ATPase. All fibers in the bat flight muscles exhibit relatively intense staining properties for NADH-TR, suggesting a high oxidative capacity. The glycolytic potential of all fibers is rather low, as assessed by stains for alpha-GPD. This two-type histochemical profile appears to parallel biphasic electromyographic patterns observed in these muscles and leads us to propose that flight muscle histochemistry and activation are mediated by a “two-gear” neuromuscular control system. In contrast, earlier studies on Tadarida brasiliensis demonstrate the existence of a “one-gear” neuromuscular control system, exemplified by the presence of one fiber type. These observations are discussed with respect to the natural history and flight styles of several species.
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    Journal of Morphology 197 (1988), S. 33-52 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distribution and histology of zymogen cells and the activity of digestive enzymes have been examined in the alimentary canal of larval, metamorphosing (stages 1-7), and adult Geotria australis (Geotriidae). Comparisons of the arrangement of the larval and adult zymogen cells are made with those observed in Mordacia mordax, a representative of the other Southern Hemisphere lamprey family (Mordaciidae), and with those reported elsewhere for holarctic lampreys (Petromyzontidae). In larval G. australis, epithelial zymogen cells are mainly restricted to the prominent pair of tubular diverticula which project forward from the oesophageal/intestinal junction. By contrast, zymogen cells of adults are present in the epithelium of both the anterior intestine and the intestinal caecum, a structure located at the new and more anterior oesophageal/intestinal junction which forms during metamorphosis. Amylolytic activity was greater in the larval divrticula than in the adult caecum, whereas the reverse was true for tryptic activity. This feature presumably reflects the high dietary contribution made by detritus and algae during the filter-feeding larval phase and by host muscle tissue during the predatory adult phase. The high tryptic activity in the caecum must promote the early breakdown of host tissue and thereby facilitate the digestion of lipids in the anterior intestine where lipolytic activity is high. At the commencement of metamorphosis, digestive activity and the number of zymogen cells declines markedly. By stage 4 the intestine has rotated anticlockwise almost 360°; the two larval diverticula have disappeared; and the new exocrine caecum of the adult has started to develop from a forward proliferation of intestinal mucosal cells. While the exocrine pancreatic tissue of larval M. mordax is unique amongst lampreys in its location within a single, large diverticulum containing an extensive network of mucosal folds, that of the adult is found in the same position as in G. australis and holarctic lampreys.
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    Journal of Morphology 197 (1988), S. 71-103 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cytoarchitectonic studies of the pretectum and diencephalon of five teleosts (Gaidropsarus mediterraneus, Syngnathus acus, Gasterosteus aculeatus, Pleuronectes platessa, and Coris julis) have shown the hypothalamus to be the most highly developed region in all five. The nucleus praeopticus magnocellularis is well developed in Coris and the euryhalines Gasterosteus and Pleuronectes; in Coris and Pleuronectes the nucleus lateralis tuberis is also prominent. Except in Gaidropsarus, however, the most striking area in the hypothalamus is the glomerulosus complex, with its voluminous nucleus glomerulosus. In Coris and Pleuronectes a glomerular offshoot of this nucleus in the dorsal thalamus is evidence of its being homologous with the nucleus anterior thalami of primitive teleosts. The nucleus diffusus is also very large in all except Gaidropsarus. In Coris and Syngnathus the saccus vasculosus exhibits a peduncle, and in Pleuronectes it invades the hypophysis. The descriptive analysis is complemented by measuring the relative size and cell density of the cell groups studied.A comparison among the five species studied shows that nuclei probably related to the olfactory system are more developed in Gaidropsarus and Pleuronectes, whereas the supposed visual nuclei are prominent in Coris, Gasterosteus, and Syngnathus but poorly developed in Gaidropsarus. In general, the findings of the present study, together with published results concerning Lizza (Gómez-Segade and Anadón, Trab. Inst. Cajal Invest. Biol. 72:187-214, 1981), show that Coris has the most complex diencephalon among these species. Moreover, Gaidropsarus presents an organization very different from that of the other five species and probably represents a parallel evolutionary lineage.
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    Notes: Electromyography and cinematography were used to determine the activity of epaxial muscles of colubrid snakes during terrestrial and aquatic lateral undulatory locomotion. In both types of lateral undulation, at a given longitudinal position, segments of three muscles (Mm. semispinalis-spinalis, longissimus dorsi, and iliocostalis) usually show synchronous activity. Muscle activity propagates posteriorly and generally is unilateral. With each muscle, large numbers of adjacent segments (30 to 100) show simultaneous activity. Terrestrial and aquatic undulation differ in two major respects. (1) During terrestrial undulation, muscle activity in a particular region begins when that portion of the body has reached maximal convex flexion and ends when it is maximally concave; this phase relation is uniform along the entire snake. During swimming, however, muscle activity passes posteriorly faster than the wave of vertebral flexion, causing the relation of muscle activity to flexion to change along the length of the snake. (2) In the terrestrial mode, the block of active muscle segments remains approximately constant in size as it passes down the snake, whereas during swimming the number of adjacent active muscle segments increases posteriorly. Despite the fact that Elaphe obsoleta has nearly twice as many body vertebrate as Nerodia fasciata (240 vs. 125), the only difference observed in the swimming of these two species is that a larger number of adjacent muscle segments is simultaneously active in comparable regions of Elaphe obsoleta than in Nerodia fasciata.
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    Journal of Morphology 197 (1988), S. 209-219 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two groups of external excretory pores associated with glandular units (AU and LPU) were observed on the labrum, one pair laterally and three pairs posteriorly. Each external pore leads to an underlying conical, flask-shaped epidermal chamber. The wide base of this chamber is perforated by an internal pore that delivers secretions from the excretory duct of a glandular unit. The chambers serve to protect the internal pores from turbulence in the outside environment. Expulsion of secretions from the chambers is probably brought about by contraction of labral striated muscles, which synchronizes opening of the AU and LPU pores. A complex funnel-shaped structure forms the internal end of the excretory duct between each chamber and the corresponding pole of accumulation for the secretory product of a glandular unit. This structure, composed of an epidermal syncytium lined by a sleeve of several aligned auxiliary cells, probably ensures a tight connection between the epidermal chamber and the syncytium. The dorsalmost glandular units (LDU) have no pores in the vicinity of their poles of accumulation. Instead they secrete through cuticular ducts delimited by aligned auxiliary cells. External pores for these canals have not yet been located. The secretions of lateral pores may be mucopolysaccharides that play an essential role in agglutination of food particles soon after capture, while the secretions of posterior pores may contain glycoproteins that mix with food only after ingestion into the buccal cavity and probably start the process of digestion.
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    Journal of Morphology 197 (1988), S. 249-268 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The process of metamorphosis in tiger salamanders, Ambystoma tigrinum, is used to investigate motor pattern conservatism in vertebrates. Specifically, we examined cranial muscle activity to determine if changes in the motor pattern are correlated with the morphological or environmental changes that occur at metamorphosis.Twenty-three variables were measured from electromyographic recordings from six cranial muscles in 13 tiger salamanders. These variables described the configuration of the motor pattern: the peak amplitude of activity, duration, relative onset, and time to peak amplitude were measured for each of the six muscles. Univariate and multivariate statistical analyses showed that there was no change in the mean motor pattern associated with the morphological transformation at metamorphosis: larval and metamorphosed individuals feeding in the water have very similar motor patterns. This was true despite significant morphological changes in the design of the feeding mechanism at metamorphosis and despite a significant decrease in aquatic feeding performance following metamorphosis.There was a change in the mean motor pattern to jaw muscles when metamorphosed individuals fed in water and on land: metamorphosed terrestrial feedings tend to have longer bursts of muscle activity then do aquatic feedings. The environmental changes in the motor pattern cannot be attributed to effects of differing fluid density or viscosity between water and air and are instead related to the shift to feeding by tongue projection on land.The decrease in aquatic feeding performance that occurs after metamorphosis is not correlated with changes in the motor pattern. Instead, the results suggest that changes in behavioral performance during ontogeny are associated with the transformation of hydrodynamic design of the feeding mechanism from uni- to bidirectional, and that motor patterns driving complex rapid behaviors may be conserved when behavior is altered by changes in peripheral morphology.
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    Journal of Morphology 198 (1988) 
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    Journal of Morphology 198 (1988), S. 15-23 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Silver impregnations, immunofluorescence microscopy, and electron microscopy of the nervous system of Velella confirm previous reports that there are two nerve nets, one composed of small and the other of “giant” neurites. Only one of these systems, the small-fibered open one, shows FMRFamide-like immunoreactivity. It appears to be primarily a sensory network. Despite presence of a neuropeptide in these neurons, they did not contain dense-cored vesicles. The “giant” nerve net (closed system) shows many connections that appear syncytial in the silver preparations. While it is confirmed that gap junctions are present between some neurites in the closed system, it is likely that fusion of neurites also occurs and that the system is a partial syncytium. Membrane complexes with gap junctions are abundant in the cytoplasm. It is suggested that fusion occurs by the engulfment of small neurons by large, resulting in an excess of cell membrane, which is internalized with gap junctions still intact. These internalized membranes appear to break up into vesicles eventually. A similar process may occur in the “giant” swimming motor neuron net of the medusa Polyorchis.
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    Journal of Morphology 198 (1988), S. 43-48 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Electron microscopy discloses nerve endings in contact with gland cells situated in the labrum of Daphnia. Swellings of nerve fibers are in close contact with gland cell membranes, either on the cell surface or inserted into infoldings of plasma membrane. The axonal processes are single or double and lack glial wrappings. Inside the nerve fibers are vesicles of different sizes and electron density. These include granular vesicles, which often are dense-cored, and also clearer vesicles.Some presynaptic differentiations lie along the contact line of the axonal process with the gland cell membrane. The significance of the vesicles is discussed in terms of their possible content of biogenic amines, as described in other invertebrates.
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    Journal of Morphology 198 (1988), S. 331-339 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Jenynsia lineata retains its embryos within the ovarian cavity for a prolonged gestation. In the absence of egg envelopes, maternal - embryonic transfer occurs through ovarian fluid across apposed epithelia, relatively lining the ovarian lumen and the surface of the embryos. There are no hypertrophied extraembryonic structures that could provide expanded exchange surfaces for the passage of nutrients beyond the 8-mm stage, but structural specializations of the ovary then form, and these may sustain embryogenesis. Outgrowths of the inner lining of the ovary, villi ovariales, enter the pharyngeal cavity of the embryos via an opercular cleft remaining from early stages of development, after depletion of yolk reserves, until shortly before term. The ovary and its villi are lined by a monolayer of squamous cells showing evidence of vesicular transport of macromolecular substances both on the apical surface and at the basolateral pole. It serves for transcellular passage of maternally derived substances rather than as a source of secretory products. Most adjacent cells interdigitate, and the epithelium is continuous except for few gaps at the villous tips, which allow paracellular passage of particulate matter. These epithelial cells contain abundant filaments, electron-dense granules within the cytoplasm and the nucleus, sparse elements of the rough endoplasmic reticulum, a Golgi apparatus, and different sorts of vacuoles. The capillaries in the intraovarian lining are spaced most densely at the ovarian wall, less so toward the tips of the villi. The villi ovariales contain a network of connective tissue that forms endotheliumlike septa, which divide the interior into numerous different-sized loculi.
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    Journal of Morphology 198 (1988), S. 189-204 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fine structure of the male germinal cells in testes of two salps, Thalia democratica and Cyclosalpa affinis, is identical. The earliest germ cells seen were spermatocytes, located at the periphery of the testis and sometimes connected by cytoplasmic bridges. They are spherical with an anucleolate nucleus, a pair of centrioles, aboundant free ribosomes, sparse rough endoplasmic reticulum, and about five mitochondria. No Golgi complex was seen. The earliest spermatids, though similar to the spermatocytes, are smaller and have only one centriole. Spermatids develop (1) singly, (2) joined by cytoplasmic bridges, or (3) in syncytia. The next stage has a flagellum, a single large mitochondrion with dense material in some intracristal spaces, and a patch of highly condensed chromatin in the nucleus adjacent to the centriole. Subsequently the nucleus and the spermatid elongate. During elongation (1) the mitochondrion remains lateral to the nucleus and the amount of intracristal material enlarges, (2) the central core of condensed chromatin increases, and (3) the remainder of the chromatin becomes organized into dense strands. When elongation is 75% complete, the dense strands of chromatin appear to coalesce, to become homogeneous and denser than the core of chromatin, and the mitochondrion transforms into dense tubules. Finally, the mitochondrion wraps around the nucleus and extends its entire length, ultimately becoming a single tubule spiraled about 45 times around the nucleus. The mature sperm head is 18 μm long, tapering from 0.8 μm posteriorly to a tip about 0.14 μm wide. There is no acrosome. The single (distal) centriole of the sperm gives rise to a 9+2 flagellum with a fuzzy coat and dense material peripheral to each of the nine doublets. Spermiogenesis in T. democratica and C. affinis is similar to that in ascidians, and the sperm share many features with sperm of colonial ascidians in the suborder Didemnidae. The results, therefore, suggest that salps are closely related to ascidians and support the view that colonial ascidians gave rise to salps.
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  • 44
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    Journal of Morphology 198 (1988), S. 231-241 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The penis of the silkmoth, Bombyx mori, consists of two parts covered with cuticle, the corpus penis and crus penis, and a third part, the radix penis, without a cuticle but surrounded by a thick sphincter. The radix penis is divisible into anterior and posterior parts. The ductus (d.) ejaculatorius passing through the penis has no secretory cells. In the anterior radix penis, the wall of the d. ejaculatorius is thin and without folds; in the posterior section, it is thick, with folds in its lumen. The glandula (g.) prostatica is divisible into anterior and posterior parts according to differences in the histological and morphological characteristics of the cells and their secretions, which contain many heterogeneous substances. In the anterior g. prostatica, secretions accumulate separately in the anterior and posterior sections before ejaculation. Unlike the posterior region, the anterior region displays a large mass(es) at the periphery of the lumen along the secretory cell layer. Judging from staining properties, the pearly body and the first layer of the spermatophore wall, which, after copulation, form in the female bursa copulatrix, seem to be derived from the secretions of the anterior and posterior regions of the g. prostatica, respectively. The secretion of the posterior g. prostatica contains initiatorin, which acts as a sperm-activating factor in the inner and outer matrices of the spermatophore. An ejaculatory valve is found between the radix penis and the g. prostatica. The opening of this valve is regulated by the surrounding sphincter, thus impeding the back-flow of secretions and seminal fluid in the radix penis and resulting in their transport outwards during ejaculation. The musculature of the d. ejaculatorius and the corpus penis promotes further transport of these secretions into the female bursa copulatrix.
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  • 45
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    Journal of Morphology 195 (1988), S. 71-81 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fully developed oral disc of the tadpole of Bufo bufo consists of dorsal and ventral labia bearing, respectively, two and three ridges bearing numerous horny denticles, a horny beak provided with jaw sheath serrations, and large lateral papillae that are borne by two cutaneous plicae. As development progresses toward metamorphosis, these structures gradually regress until they disappear. Each cusped clavate labial denticle adheres, by means of a thin peduncle, to a similar labial denticle fixed in the lip and formed by a group of three or four cells that keratinize gradually and thus present remarkable differences in their morphology. Once all the cells of a group have been converted into horny tissue, the denticle sheds and is replaced by the underlying one. The beak serrations also are horny structures; each consists of a columnar band of cells which undergoes a gradual keratinization. The horny cells that detach themselves at intervals, being replaced by those of the underlying anlagen. The labial denticles and the beak serrations keratinize in two distinct ways. In the former, the desmosomal filaments appear to play an important role whereas, in the latter, the keratin seems to be synthesized “ex novo” by the ribosomes.
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  • 46
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    Journal of Morphology 195 (1988), S. 177-188 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Spermatogenesis of the sea urchin Paracentrotus lividus has been studied at the ultrastructural level after conventional staining of thin sections and after en bloc silver staining. Cytoplasmic dense bodies are present in all steps of spermatogenesis except in late spermatids and spermatozoa. These bodies are closely associated with the development of centrioles and of the acrosomal vesicle during spermiogenesis. After it first appears, acrosomal vesicle is linked to the nuclear envelope by electron-dense material and subsequently acquires a dense core. Later the acrosomal vesicle moves to the apical pole of the cell while maintaining its connection to the nucleus. Although chromatin was highly condensed in the head of spermatozoa, one or more nuclear vacuoles within the nucleus were found to contain uncondensed chromatin fibers. Silver nitrate stains several nuclear and cytoplasmic structures. In the nucleus it stains the nucleolus, specific regions at the periphery of the chromatin, the synaptonemal complexes, the nuclear basal fossa, and the nuclear vacuoles of spermatozoa. In the cytoplasm, silver stains the cytoplasmic dense bodies, the material that connects the acrosomal vesicle to the spermatid nucleus, the spermatozoan subacrosomal and periacrosomal materials, the intercellular bridges of spermatids, and the centrioles. Silver staining is abolished by pretreatment with pronase E, suggesting that silver staining is due to protein.
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  • 47
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    Notes: The ultrastructure of the sensilla, and other structures, within the precibaria of eight species from three subfamilies of leafhoppers (Homoptera: Cicadellidae) were examined with scanning electron microscopy. The types and grouping of the 20 precibarial sensilla in seven of these species were similar to those observed previously in Macrosteles fascifrons Stål. Oncometopia nigricans (Walker) also displayed similar sensilla groups; however, it had 30 sensilla. The species examined differed chiefly in the exact location and arrangement of the sensilla. The possible significance of the differences relative to leafhopper feeding is discussed. The precibarial chemosensilla may provide chemosensory evaluation of fluid in the food canal and precibarium prior to ingestion or egestion.
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  • 48
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    Journal of Morphology 176 (1983) 
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  • 49
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    Journal of Morphology 176 (1983), S. 131-139 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: During the sahelian dry season (November to June) the lizard Varanus exanthematicus fasts, and during these 8 months its pancreatic acinar cells lack zymogen granules and show an inactive Golgi body and damaged mitochondria. The main peculiarity can be observed in the granular endoplasmic reticulum (GER): Each acinar cell posesses a great number of GER vesicles (mean diameter 0.15 μm) and a large spheroid GER resulting from either the nesting of some cisternae or the rolling up of a single cisternae on itself. Attention is focused on the possible relationship between this ultrastructure and alteration of protein metabolism.
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  • 50
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    Notes: The structure and secretory activity of the accessory salivary gland in two species of Conus were examined using routine and histochemical techniques of light, scanning and transmission electron microscopy.The composite layers of the accessory salivary gland of Conus are a luminal epithelium, fibromuscular layer, submuscular layer, and a capsule. In C. flavidus and C. vexillum, the luminal epithelium is formed by epitheliocytes and cytoplasmic processes extending from the secretory cells, whose perikarya form the submuscular layer. The processes carry secretory cell products (chiefly Golgi-derived glycoprotein) across the fibromuscular layer and terminate between epitheliocytes (at the bases of the secretory canaliculi) or beyond the surface of the epithelial cells. Conus vexillum is distinguished from C. flavidus by its high content of lipofuscin. Epitheliocytes are the only microvillated cells in the accessory salivary gland of Conus. In C. flavidus, epitheliocytes extrude secretory granules, various types of cytoplasmic blebs and clear vesicles by apocrine “pinching off”. Clear vesicles are shed from the tips of microvilli. The luminal epithelial cells of C. vexillum similarly egest clear vesicles, but normally undergo additional holocrine secretion to release lipofuscin.The secretions of epitheliocytes appear to be major products of the accessory salivary gland: consideration of secretory activities by both epitheliocytes and secretory cells will therefore be necessary when directly investigating accessory salivary gland function in Conus.
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  • 51
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    Journal of Morphology 176 (1983), S. 155-169 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cytological changes following transection of the proximal root of the trigeminal ganglion in adult rats were assessed by light and electron microscopy. Radices were transected about 3-5 mm from the ganglia and animals were killed from 1 to 60 days after the operation. Light microscopically, it was found that all Nissl granules became uniformly stained and evenly distributed throughout the cytoplasm within 3 days. Three types of cell alteration involving Nissl granules occurred within 3 to 12 days after the operation: (1) chromatolysis, (2) dark staining of the cytoplasm accompanied by an increase of Nissl granules, and (3) faint staining of the cytoplasm accompanied by dispersion of Nissl granules. Electron microscopically, the chromatolysis pattern was characterized by peripheral concentration of the granular endoplasmic reticulum (gER) and ribosomes in the cytoplasm. Neurons of the darkstaining type showed an increased number of polysomal complexes throughout the cytoplasm, whereas those of the faint-staining type had diffusely dispersed cisternae of the gER which were shortened and bore reduced numbers of attached ribosomes. Perinuclear localization of profiles of Golgi complexes disappeared temporarily 1-3 days after the operation, but the normal perinuclear pattern appeared to return after 1 week. Enzyme histochemistry of acid phosphatase activity revealed an increase in the number of very fine reaction products in the cytoplasm up to 14 days following the operation. Cells recovered the normal pattern of Nissl staining by 48 days. Myelin figures, which are rarely observed in normal ganglia, were still observed in dense lysosomal bodies after 30 days. Nuclear size in affected neurons steadily increased up to about 2 weeks postoperation but returned to normal by 48 days.
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  • 52
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    Journal of Morphology 177 (1983), S. 69-87 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Profiles of muscle fiber types and pharyngeal jaw dentition vary in accordance with trophic demands and skeletal organization in teleost fishes. Carnivorous, omnivorous, and molluscivorous members of the ecologically analogous Cichlidae and Centrarchidae were compared in terms of their pharyngeal jaw anatomy and branchial muscle histochemistry. The two families differed greatly in patterns of tooth form, wear, and replacement. Four muscle fiber type patterns were discoverd: (1) single fiber, (2) zoned, (3) mosaic, and (4) zoned-mosaic. Multiple fiber type muscles were more prevalent in fishes that masticate tough foods with their pharyngeal jaws. Such muscles were also more prevalent in cichlids than in centrarchids. It appears that muscles with multiple fiber types in lower vertebrates are, as a rule, compartmentalized, whereas in higher vertebrates, multiple fiber type muscles are a musaic matrix. The occurrence of mosaic patterns in some fish branchial muscles, however, suggests that mosaic muscles are initially single fiber type muscles exposed to complex functional demands, such as food preparation. Furthermore, it is plausible that the evolutionary replacement of the lower vertebrate zoning pattern by the higher vertebrate mosaic matrix is directly related to the effects of gravity, a force more influential on terrestrial than on aquatic organisms.
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  • 53
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    Journal of Morphology 177 (1983), S. 109-124 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The bile ducts in the liver of larval sea lamprey, Petromyzon marinus, undergo programmed degeneration during metamorphosis. The degenerative process is most dramatic in the middle metamorphic stages (3-5), and is asynchronous, occurring more rapidly in small peripheral biliary components than in larger, medial ducts. All classes of bile ducts within the biliary tree exhibit similar histological changes during regression.The initial evidence of degeneration in the epithelium is a folding of the basal lamina, and this is accompanied by cell shrinkage and disruption of cell order. “Shedding” of microvilli and cytoplasmic constituents then takes place at the apical surface resulting in the accumulation of periodic acid-Schiff positive membranous debris in the lumen. The apperance of “hyalin bodies” in the lumen coincides with the depletion of intermediate-sized filaments from the cytoplasmic matrix. Numerous, large dense bodies, myelin figures, and autophagic vacuoles are consistently observed in necrotic cells. Following cytolysis, bile duct remnants become ensheathed within regions of fibrosis. Ultimately, these fibrous regions are replaced with cords of hepatocytes. By stage 7, all bile ducts have disappeared.The events of biliary atresia in lampreys are comparable to tissue regression which is associated with normal development and pathological conditions in other vertebrates but are particularly reminiscent of those in human biliary atresia. The unique ability of the adult lamprey to survive without bile ducts enhances the value of this organism as an experimental model for studying human biliary atresia.
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  • 54
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    Journal of Morphology 177 (1983), S. 181-190 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: In Pieris rapae the external structure of meso- and metathoraces includes intersegmental folds as well as 4 transverse shallow grooves on the dorsal side and 2 on the ventral side in addition to several leg segments. The musculature of both segments is very similar, but has some segment-specificity. Sixty-seven muscle are common to both hemi-mesothorax and hemimetathorax. Four are specific for the mesothorax and 3 for the metathorax. Moreover, thickness and number of subdivisions of some common muscles are specific for one segment. Attachments areas of all muscles are clearly indicated on the pattern of cuticular grooves. They have a tendency to pile up or line up to form various sizes of united attachment sites, most of which are located on or near the cuticular groove. On the other hand all grooves have some muscle attachment sites. Thus, attachments of larval muscles may relate to formation of the grooves. Comparison of the musculature with that previously reported for some lepidopteran larvae shows a major common basic plan and minor interspecific variation. Its attachment sites allow the role of each muscle to be inferred for body contraction, bending, and twisting, and for leg direction and flexion.
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  • 55
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    Journal of Morphology 177 (1983), S. 245-254 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Striking ultrastructural and hormonal parameters of premature menopause and aging are reported in female Xyleborus ferrugineus fed cholesterol, rather than 7-dehydrocholesterol, as a sole dietary sterol. The titer of free ecdysteroids in such 63-day-old females remained abnormally elevated through the period of the ovarian cycle. A similar plateauing of such elevated titer also occurred in 147-day-old, irregularly cycling females fed only cholesterol as the dietary sterol. These hormonal changes in menopausing X. ferrugineus females seem especially analogous to the maintenance of an elevated concentration of 17-β-estradiol through the estrous, as well as the proestrous, ovary of aged irregularly cycling rats. The highly abnormal ultrastructure of ovaries of X. ferrugineus females aged 216 days on a diet containing cholesterol as the sole sterol seems quite analogous to that of the nonovulatory follicles in older, irregularly cycling rats. Our new findings involving aging X. ferrugineus females indicate further the usefulness of an insect model to study aging processes.
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  • 56
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    Journal of Morphology 177 (1983), S. 277-299 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology of neurons in the ventral basal complex (VBC) of the adult opossum (Didelphis virginiana) is described from thick coronal brain sections, using Golgi-, horseradish peroxidase (HRP)-, and Nissl-staining methods. Soma cross-sectional area, dendritic field shape, and the number of appendages (spines) in a defined major branch zone (MBZ) are quantified and statistically analyzed. Results indicate that neurons in opossum VBC have relatively large cell bodies, dendrites which branch in a tufted pattern, and numerous dendritic appendages. These neurons are designated as relay cells because of (1) their tufted dendritic branch patterns, considered characteristic of thalamic relay cells (Ramon-Moliner, '62), and (2) the similarity of their soma sizes with HRP-labeled somata after somatosensory cortical injections. Neurons with traditionally described interneuron morphology do not appear to be present in the VBC of this animal, and, in this respect, the neuronal morphology of opossum VBC is similar to that in rat (McAllister and Wells, '81).Based on statistical analysis of the structural features observed, the presumed relay cells in opossum VBC do not show significant differences in morphology, and consequently are not subdivided into classes. Opossum VBC neurons are recognized as forming a single category in which broad and continuous variations in morphology are indicated. Recognition of a singular class of relay cell is consistent with descriptions for rat and cat VBC (Scheibel and Scheibel, '66), but at variance with a previous report for the primate Galago VBC (Pearson and Haines, '80) subdividing thalamic relay cells into Types I, II, and intermediate categories.
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    Journal of Morphology 177 (1983), S. 125-125 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 58
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    Journal of Morphology 177 (1983), S. 145-156 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Flashing fireflies were permitted to breathe osmium tetroxide vapor, after which the lanterns were removed and the sites of absorption of the osmium into the tissues were detected in two ways: (1) by sonication to remove soft tissues, that is, those that had not been fixed by the osmium gas, and (2) by intensification with thiocarbohydrazide and silver nitrate, in a modification of the osmium-thiocarbohydrazide-osmium (OTO) stain technique. The results of both procedures indicate that the gas first enters into the tissues at the level of the tracheoles. These findings may be interpreted as underscoring the importance of the tracheolar cell and the tracheal end organ in the control of oxygen entry into the lantern tissues, and the implications of the results in the oxygen regulation theory of flash control are discussed.
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  • 59
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    Journal of Morphology 177 (1983), S. 191-203 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The external structure of the 1st (AS1) and 4th abdominal segments (AS4) of Pieris rapae is described in terms of pattern of shallow grooves on the cuticle. Both segments have 5 dorsal costae, 3 ventral costae, and an antero-posterior line in addiction to the dorsal and ventral intersegmental folds and a spiracle. AS4 has a pair of prolegs. The musculatures of AS1 and AS4 consist of 44 and 51 muscles, respectively. As in thoracic ones, most attachments of the muscles are located on the cuticular grooves. AS1 and AS4 have similar musculatures. Common to both segments are 89% of AS1 muscles and 84% of AS4 muscles. AS1 has 6 muscles homologous to proleg ones of AS4, including proleg retractors and plantar retractors. Comparison of the musculature of proleg-bearing abdominal segments among different species shows that abdominal musculature of lepidopteran larvae has major homologous and minor specific muscles. From the muscle attachment sites, the role of each muscle is inferred for contraction and bending of the body, lifting up its venter, taking off the crockets from the substrate, and retraction, lateral abduction, and anterior movement of the proleg.
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  • 60
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    Journal of Morphology 177 (1983) 
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  • 61
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    Journal of Morphology 177 (1983), S. 231-243 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The serratus superficailis metapatagialis (SSM) of pigeons is a skeletal muscle with unusual properties. It lies between the ribs and the trailing edge of the wing, where it is attached to the skin by a system of smooth muscles having elastic tendons. Wing movements during flight induce marked changes in this muscle's length. The SSM inserts onto the deep fascia, and at its termination the skeletal muscle contains large numbers of microtubules. Many myofibrils attach to leptomeric organelles, which then attach to the terminal end of the skeletal muscle fiber. The deep fascia next connects to the dermis of the skin by bundles of smooth muscles that have elastic tendons at both ends. This system allows large movements of the muscle while preventing its fibers from overstretching. The movements and presumed forces acting at this muscle make the presence of sensory receptors such as muscle spindles unlikely. Spindles are absent in this muscle.
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  • 62
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    Journal of Morphology 177 (1983), S. 301-317 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The relationship between the hair cell orientation pattern and innervation in the saccule and lagena of the teleost Helostoma temmincki (the kissing gourami) was investigated with scanning electron microscopy and the Winkelmann-Schmitt silver impregnation technique. The hair cell pattern in the saccule consists of four orthogonally oriented groups. The anterior two groups are oriented along the animal's rostrocaudal axis, and the posterior two are oriented along its dorsoventral axis. The pattern of hair cell orientations in the lagena is a typical bidirectional one. Two divisions of the eighth nerve innervate the saccule. The anterior division innervates the horizontally oriented hair cell groups, and the posterior division innervates the dorsoventrally oriented groups. A single nerve innervates the lagena, with the majority of fibers innervating one or the other of the two lagenar hair cell groups. The segregated pattern of innervation according to hair cell orientation groups in the saccule was confirmed in other species. Individual types of axonal terminations appear to innervate hair cells of specific ciliary bundle types.
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  • 63
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    Journal of Morphology 178 (1983), S. 155-177 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Sea anemone gametes arise in the endoderm but migrate into the mesoglea at an early stage. In order to observe this process, large individuals of Actinia fragacea were collected from the same intertidal location at regular intervals over a 2-year period, and their gonads were examined by light and electron microscopy.The cellular origin of the oocytes is unclear, but the smallest recognizable oocytes are rounded cells, 6-8 μm in diameter, with relatively large nuclei which may contain synaptinemalcomplexes. Their cytoplasm contains numerous ribosomes, a flagellar basal-body-rootlet complex, and distinctive dense structures also present in male germ cells but not found in anemone nonger- minal cells. During the endodermal phase of growth, the density of the oocyte nucleus increases, a single nucleolus becomes prominent, and mitochondria and glycogen accumulate in the cytoplasm. Most oocytes, but not all, only begin major vitellogenesis after entry into the mesoglea. Most oocytes enter the mesoglea before they attain a diameter of 25 μm.The oocytes migrate toward and enter the mesoglea by a process resembling amoeboid movement. During entry, the oocytes are constricted into a characteristic “hourglass” shape and become covered by a basal lamina continuous with that of the gonad epithelium. The last part of the oocyte to enter the mesoglea forms an intimate relationship with the surrounding endodermal cells, which is maintained after entry is complete, and is thought to be important in the establishment of the trophonema.
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    Journal of Morphology 178 (1983), S. 267-284 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The surface of a mature, pelagic C-O sole egg is composed of polygonal chambers having four to eight sides, most of which are hexagonally shaped. This honeycomb pattern initially appears on primary oocytes as a thin layer of compact, electron-dense material. Discrete thickenings begin to develop on the envelope of perinuclear stage oocytes. The thickenings lengthen and thin to form the hexagonal walls of the envelope in oocytes undergoing yolk vesicle formation. The walls of each hexagonal chamber occur in an area corresponding to the lateral margins of the adjacent follicle cell, suggesting that the hexagonal walls are produced by the follicle cells. The hexagonal layer is nearly complete at the beginning of vitellogenesis, and as vitellogenesis continues, a striated envelope layer composed of fibrillar lamellae develops between the oocyte and the hexagonal layer. The striated layer appears to be secreted by the oocyte. After vitellogenesis is completed, oocytes are ovulated and double in size during a period of maturation. Concurrently, the striated primary envelope stretches and thins into eight to nine horizontal lamellae. On the mature egg surface, the polygonal chambers are about 24-31 μm in diameter. Within each chamber there is a subpattern of polygonal areas; each polygon is 1.5-2.0 μm in diameter, and circumscribes a pore canal opening. This exceptional envelope may furnish the egg with some degree of protection, resiliency, and buoyancy, but its specific functions are not known.
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  • 65
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    Journal of Morphology 178 (1983), S. 125-138 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Scanning electron microscopy of microcorrosion casts was used to visualize circulatory pathways of the intermediate circulation in nonsinusal spleen of cat. The marginal sinus (MS) around lymphatic nodules is a distinct vascular space which fills preferentially before the filling of the marginal zone (MZ) and surrounding red pulp occurs. The MS, which has a plentiful vascular supply, does not usually enclose the nodule completely. From the MS, flow occurs radially outwards into the MZ. Corrosion casts and histological sections both showed that a diversity of forms of the MZ exists: The thickness of MZ and the arrangement of its reticulum vary among nodules and between different areas of the same nodule, from a complete absence to a region of up to 50 μn width.No direct arteriovenous connections were found (in contrast to dog spleen: Schmidt et al., '83b). Aside from capillary endings in the MS and MZ, all arterial capillaries terminate in the reticular spaces of the red pulp, i.e., the circulation appears to be entirely “open.” From each capillary termination a great variety of flow pathways through the reticular meshwork to the pulp venules is available; some of these routes are quite long but others may involve distances as short as 15-25 μm. Evidence of flow into ellipsoid sheaths was abundant in casts from dilated spleens, but scarce in contracted spleens. In contrast to the extensive system of interconnected venous sinuses in dog spleen, the pulp venules found in cat spleen are nonanastomosing, shorter, and much smaller in caliber, and all receive flow freely from the reticular mesh-work via open ends and fenestrations in their walls.
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  • 66
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    Journal of Morphology 178 (1983), S. 187-206 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The ultrastructure of pike peripheral blood cells, lymphocytes, thrombocytes, granulocytes, and monocytes is described. At present there are no reliable criteria for differentiating between round thrombocytes and small lymphocytes of fish on a routine basis. At the ultrastructural level thrombocytes could be clearly differentiated from lymphocytes by cytoplasmic canals and vesicles, marginal microtubules, and large glycogen deposits. Electron microscopic identification of thrombocytes was confirmed by examining the ultrastructural features of a purified thrombocyte fraction. In addition, a preliminary investigation of the structure of the haemopoietic cells in the thymus, anterior kidney, and spleen was carried out.
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  • 67
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    Journal of Morphology 178 (1983), S. 207-224 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Innervation of the tongue and associated musculature in plethodontid salamanders was studied using Palmgren stained sectioned materials, fresh dissection, and whole mounts of experimental specimens treated with horseradish peroxidase (HRP). Species studied were chosen to represent modes of tongue projection recognized by Lombard and Wake ('77). Special attention was given to species of the genera Plethodon, Batrachoseps, Pseudoeurycea, and Hydromantes, but representatives of other genera were investigated. As expected we found that cranial nerves IX and X and spinal nerve 1 supplied the muscles involved in tongue movement. The peripheral courses of the nerves were traced, and both functionally related and phylogenetically determined routes were found. As relative projection length increases, the nerves supplying the tongue tip also increase in length. When the tongue is at rest the long nerves are stored in coils. The coil of ramus lingualis lies between the ceratobranchials, but that of ramus hypoglossus is more variable, although constant within a species. Ramus hypoglossus bifurcates into separate branches to tongue and anterior musculature of the floor of the mouth. In generalized, presumably primitive, modes the bifurcation and coiling are far anterior. In most of the tongue projection modes bifurcation is relatively posterior, but in one, bifurcation is anterior, but coiling is relatively posterior in position. The most unusual condition is in Hydromantes, in which bifurcation is relatively posterior and a coiled ramus hypoglossus joins a coiled ramus lingualis to form a unique, coiled common ramus to the tongue tip. Hydromantes has the greatest projection distance of any salamander.
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    Journal of Morphology 178 (1983), S. 247-265 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A study of ovarian structure in adult Alligator Lizards (Gerrhonotus coeruleus) was conducted by light microscopy and transmission electron microscopy. Particular attention was directed to characterizing the ultrastructure of germ-line cells, prior to follicle formation. General ovarian structure in this lizard is similar to that of other lizards. The paired organs are hollow, thin-walled sacs containing follicles in roughly 3 to 4 size classes. Ovarian germinal tissue consists of oogonia (diploid cells which divide mitotically) and oocytes (meiotic cells), intermixed with ovarian surface epithelial cells. Germ cells reside in two dorsal patches of epithelium per ovary (germinal beds), as is common in lizards. Oogonia in interphase show a highly dispersed chromatin pattern. Within oogonia cytoplasm, Golgi complexes are scarce, rough endoplasmic reticulum is absent, and lipid droplets are rare. Ribosomes are scattered in small clusters. Small, round vesicles are common in all oogonia; glycogen-like granules are present in some. Mitochondria form a juxtanuclear mass within which groups of several mitochondria surround a dense granule. “Nuage” granules also are found unassociated with mitochondria. Oocytes are present in stages of meiotic prophase up to diplotene. Synaptinemal complexes are seen in several (pachytene) cells. The cytoplasm of oocytes differs from that of oogonia in that mitochondria do not form groups, and nuage and glycogen are absent, whereas small round vesicles and large irregular vesicles are common. The ultrastructural similarities in germ cells of a reptile as compared to those of other vertebrates strengthens the notion that germ-line cells possess (or lack) qualities related to the undifferentiated state of these cells.
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  • 69
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    Journal of Morphology 178 (1983), S. 285-301 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The cochlear nuclear complex was investigated in snakes of the advanced family Colubridae and the primitive family Boidae. This study was undertaken in an attempt to correlate the elaboration of the cochlear nuclei with behavior and phylogeny and to elucidate the relative effects of these factors on the evolution of the cochlear nuclear complex. Fifty-five brains, of 14 colubrid species and three boid species, were examined to collect data on neuron diameter, neuron population, nuclear volume, and neuronal density of the cochlear nuclear complex and of its component nuclei (nucleus angularis and nucleus magnocellularis). Intraspecific and interspecific comparisons of the data were performed by nested analysis of variance. The species were grouped by cluster analysis and ranked on the basis of the morphometric parameters. Interspecific comparisons indicate that the elaboration of the cochlear nuclei is related, first, to prey preference and, second, to habitat preference. The most elaborate cochlear nuclei occur in species with a preference for vertebrate prey. Burrowing species that prey on vertebrates exhibit the highest degree of elaboration of the cochlear nuclei. In some burrowing species, the nucleus magnocellularis is differentiated into medial and lateral subdivisions. The primitive boid snakes show greater elaboration of the cochlear nuclei than do most of the advanced colubrid snakes. The elaboration of the cochlear nuclear complex in snakes seems to reflect the influence of both behavior and phylogeny. Further investigation of primitive snakes of varied behaviors is needed to establish more clearly the influence of phylogeny on the evolution of the cochlear nuclear complex.
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    Journal of Morphology 175 (1983) 
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    Journal of Morphology 175 (1983), S. 27-32 
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    Notes: Three pairs of specialized axons found in other muscoid flies are absent in the tsetse, Glossina morsitans, which also lacks the tergotrochanteral muscle. Neither light nor electron microscopy could demonstrate any evidence for the cervical giant fiber axon, the peripherally synapsing axon, or the tergotrochanteral motor axon. The specialized characteristics of these axons must have been altered during the evolution of Glossina. This divergence of individual neurons from the more typical muscoid pattern not only demonstrates the evolutionary modification of specific identified cells; it may also provide an opportunity to study the ontogenetic determination of unique neuronal features.
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    Journal of Morphology 175 (1983), S. 65-72 
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    Notes: A light microscopic investigation of the histological development of the terminal airways of 18 Stenella attenuata and two S. longirostris showed the lungs to be in a glandular stage of development until 3 months postimplantation (p.i.) age. By 3.5 months (p.i.) the lung was at the canalicular stage. At 4 months mesenchymal rings and muscular bands were in a sphincterlike arrangement around terminal bronchioles. At 7 months (p.i.) the alveolar stage occured. About 8-9 months cartilaginous rings were present and in association with myoelastic sphincters. Their function remains an enigma, even though many hypotheses as to function have been proposed. We suggest that the presence of well-developed sphincters and cartilage in the neonate may give clues to their function as well as offer potential experiments that would not be as suitable in the adult porpoise.
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    Journal of Morphology 175 (1983), S. 101-113 
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The neurons of the trigeminal ganglia of the rat and chicken were characterized by means of light microscopic, electron microscopic, and histochemical methods. Light microscopy disclosed four types of neurons, based on the characteristics of Nissl granules: (1) large neurons with diffusely distributed and very fine granules, (2) neurons containing coarse and sparsely distributed Nissl granules, (3) neurons containing dense Nissl granules of varying size, and (4) small neurons with granules concentrated peripherally. Electron microscopy allowed further definition of these four types of neurons by the length and arrangement of flattened cisterns of granular endoplasmic reticulum (gER) and the number of neurofilaments. Type 1 cells were largest, with a mean nuclear area of 139.8 ± 28.3 μm2. Type 4 cells were smallest, with a mean nuclear area of 74.6 ± 20.9 μm2. The mean nuclear areas of type 2 and 3 cells were intermediate to those of the type 1 and 4 cells. Type 3 and 4 neurons lacked neurofilaments. Four forms of Golgi apparatus were found: (1) large bent grains forming a network throughout the soma, (2) dispersed fine granular deposits, (3) fine or small granules, and (4) coarse bent deposits arranged confluently in the perinuclear zone. In some rat neurons, the concentration of acid phosphatase reaction products suggested a high enzymatic activity, whereas the chicken ganglion cells showed no such concentration. These findings are discussed and compared with the classifications of previous studies.
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    Journal of Morphology 175 (1983), S. 171-194 
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    Notes: The epidermis of the land planarian Bipalium adventitium was examined by light and electron microscopy. In all regions, the epidermis consists of a simple columnar ciliated epithelium associated with a prominent basement membrane. The epithelial cells, possessing abundant microvilli and poorly developed terminal webs, are conjoined laterally at their apical ends by septate junctions. The epidermis of the creeping sole is distinguished from that of adjoining regions by a “insunken” condition of the epithelial cells, a greater number of cilia per cell, and an absence of glandular secretions other than mucus. The insunken cells of the sole possess large glycogen disposits and attributes of metabolically active cells. Unusual intranuclear inclusions of unknown significance are also found in many of the epidermal cells in all regions. The basement membrane lacks distinct layering and consists of fine fibrils displaying a beaded appearance but no obvious cross-banding. Histochemical tests indicate that the fibrils are collagenous. In addition to mucus, secretory material found in nonsole regions includes lamellated granules and rhabdites, both stained intensely by acidic dyes. Rhabdites and the basement membrane also contain disulfide-enriched proteins. In scanning electron micrographs, the sole appears as a faint, longitudinally oriented band extending along the entire length of the animal. In all regions except the sensory border of the head, the microvilli are generally obscured by the densely arranged cilia. The sensory border consists of a row of toothlike papillae and grooves covered almost exclusively by microvilli, small club-shaped structures, and larger spherical protrusions.
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    Journal of Morphology 175 (1983), S. 279-292 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Investigations of the structure and function of the flexor carpi radialis muscle (FCR) in the cat have led to the hypothesis that the compartmentalized (nonuniform) distribution of fiber types within the muscle relate to the complex motor skills of the cat. To test this hypothesis a study was undertaken to compare the FCR in four mammalian species of similar body size but with different forelimb motor tasks. The species chosen were: dog, opossum, armadillo, and cat. Comparisons were made among species with regard to general muscle morphology, fiber types and sizes, fiber proportions, and fiber distriburtions. The FCR of all species was morphologically similar and contained three muscle fiber types (SO, FOG, and FG). The mean area of muscle fibers was largest in opossum, while the FCR fibers of dogs were smallest. The percentage of SO fibers in the dog FCR was greater than in the other species studied. The opossum FCR also contained a high percentage of SO fibers. The armadillo FCR consisted of a high percentage of FG fibers. In the cat FCR the percentages of all three fiber types were similar. For each species, individual fiber proportions were in agreement with the results for fiber percentages. Compartmentalized distribution of fiber types existed in each species with the dog having the most compartmentalized fiber type distribution and the cat the least compartmentalized distribution. Therefore it seems that the compartmentalized organization of the FCR is not related to any specialized motor task, but may be a generalized pattern associated with motor patterns shared among all species studied.
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    Journal of Morphology 176 (1983), S. 15-29 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Tree shrews have relatively primitive tribosphenic molars that are apparently similar to those of basal eutherians; thus, these animals have been used as a model to describe mastication in early mammals. In this study the gross morphology of the bony skull, joints, dentition, and muscles of mastication are related to potential jaw movements and cuspal relationships. Potential for complex mandibular movements is indicated by a mobile mandibular symphysis, shallow mandibular fossa that is large compared to its resident condyle, and relatively loose temporomandibular joint ligaments. Abrasive tooth wear is noticeable, and is most marked at the first molars and buccal aspects of the upper cheek teeth distal to P2. Muscle morphology is basically similar to that previously described for Tupaia minor and Ptilocercus lowii. However, in T. glis, an intraorbital part of deep temporalis has the potential for inducing lingual translation of its dentary, and the large medial pterygoid has extended its origin anteriorly to the floor of the orbit, which would enhance protrusion. The importance of the tongue and hyoid muscles during mastication is suggested by broadly expanded anterior bellies of digastrics, which may assist mylohyoids in tensing the floor of the mouth during forceful tongue actions, and by preliminary electromyography, which suggests that masticatory muscles alone cannot fully account for jaw movements in this species.
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    Journal of Morphology 176 (1983), S. 61-87 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Notes: Subungulate hyraces are similar to the condition assumed to have characterized primitive ungulates and subungulates by virtue of their small body size, relatively unspecialized cranial and postcranial anatomy, and primitive type of lophodont dentition. The muscles of mastication of Procavia habessinica and Heterohyrax brucei are here compared with those of other mammals, both with ungulates, as an example of more specialized mammals, and with opossums, as an example of more generalized mammals, to determine aspects of hyrax myology that represent the retention of a condition primitive for herbivorous mammals.The masticatory muscles of hyraces retain the primitive ungulate/subungulate condition in the large, complexly subdivided temporalis, and in the enlarged, pinnated, bilayered medial pterygoid. The medial pterygoid originates from the pterygoid hamulus, a condition that may also be primitive for this assemblage. The large complex superficial masseter is derived compared with the condition in ruminant artiodactyls, but may represent the condition primitive for perissodactyls. The architectural modifications of this muscle in hyraces may represent adaptations to allow a wide gape threat display.Hyraces possess a posterior belly of the digastric alone, paralleling the condition in some perissodactyls. They possess a large and complexly subdivided styloglossus, which may be a shared derived character of subungulates. Hyraces are unique among ungulates and subungulates in the extreme reduction of the anterior hyoid cornua, and may be unique among mammals in the development of paired lingual processes from the ceratohyal ossifications.
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    Journal of Morphology 176 (1983), S. 121-129 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The inner ears of a few fishes in the teleost superorder Ostariophysi are structurally unlike those of most other teleosts. Scanning electron microscopy was used to determine if other ostariophysans share these unusual features. Examined were the families Cyprinidae, Characidae, and Gymnotidae (all of the series Otophysi), and Chanidae (of the sister series Anotophysi), representing the four major ostariophysan lineages, the auditory organs of which have not yet been well described. Among the Otophysi, the saccular and lagenar otolith organs are similar to those reported for other ostariophysans. The lagena is generally the larger of the two organs. The saccular sensory epithelium (macula) contains long ciliary bundles on the sensory hair cells in the caudal region, and short bundles in the rostral region. The saccule and the lagena each have hair cells organized into two groups having opposing directional orientations. In contrast, Chanos, the anotophysan, has a saccular otolith larger than the lagenar otolith, and ciliary bundles that are more uniform in size over most of its saccular macula. Most strikingly, its saccular macula has hair cells organized into groups oriented in four directions instead of two, in a pattern very similar to that in many nonostariophysan teleosts. We suggest that the bi-directional pattern seen consistently in the Otophysi is a derived development related to particular auditory capabilities of these species.
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    Journal of Morphology 176 (1983), S. 171-180 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Discrete and multiple cytoplasmic regions become apparent during oogenesis in the dragonfly oocyte that are thought to arise from the nucleus (nucleolus) earlier in development, and on the basis of previous cytochemical tests, they are believed to contain ribonucleoprotein. These distinct cytoplasmic regions have been called fibrogranular bodies since they are composed of (1) a multitude of small granules ( ∼ 6-16 nm) and (2) interconnected fibrillar elements ( ∼ 2-4 nm wide). Since the fibrogranular bodies have not been isolated, they have not been biochemically characterized and their composition is unknown. However, it has been suggested that this material, in part based on other studies, may represent stored developmental information, perhaps including mRNA, rRNA, and protein. Prior to vitellogenesis, but continuing throughout the process, annulate lamellae progressively differentiate within the fibrogranular bodies. After annulate lamellae have differentiated inside the fibrogranular bodies, many of the lamellae extend into the surrounding cytoplasm as elements of rough-surfaced endoplasmic reticulum (rER). There appears to be a gradual dispersal of material as more and more annulate lamellae form within the fibrogranular bodies such that very late in oogenesis, it is difficult to observe the fibrogranular material. However, extensive numbers of polyribosomes and many parallel lamellae of rER are present. The variations noted with respect to the polyribosomes, fibrogranular bodies, and pores of the annulate lamellae suggest that pores of annulate lamellae are important in the processing or activation of “stored information” for subsequent development, perhaps including a role in polyribosomal assembly.
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    Journal of Morphology 176 (1983), S. 225-233 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Adult female white-footed mice, Peromyscus leucopus, were exposed to long (LP) or short (SP) photoperiods for 6 weeks (experiment I). Another group of animals was kept for 6 weeks in SP, then injected SC with 30 μg prolactin twice daily for 2, 3, 4, or 6 days (experiment II). Ovaries from the mice in both experiments were weighed and serially sectioned for light microscopic examination of regressing corpora lutea. In experiment I, it was observed that vessels supporting corpora lutea were dilated, and that their endothelium was either undergoing necrosis or it was missing. Pronounced changes of luteal capillaries led to rupture and intraluteal hemorrhage, thus opening the capillary bed. Regressing luteal cells became segregated and seemed to invade the vascular system passively. They were seen as luteal cell thrombi in medullary veins. This luteolytic course termed “rapid luteolysis” was most apparent in SP ovaries. It differed from “retarded luteolysis,” which represents the well-established luteolytic model of auto- and heterophagocytosis. In experiment II, there was a statistically significant decrease in ovarian weight 4 days after prolactin treatment in comparison with saline-treated controls. At the light microscopic level, signs of both rapid and retarded luteolysis were present, but not intensified. It is concluded: (1) The concept of rapid luteolysis represents a reasonable working hypothesis. (2) Prolactin, though luteolytic at the macroscopic level, failed to produce evidence of increased rapid or retarded luteolysis at the light microscopic level.
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    Journal of Morphology 176 (1983), S. 261-287 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This report is a comprehensive fine structural analysis of the morphological changes occurring during metamorphosis of the marine hydrozoan Mitrocomella polydiademata. Five stages are recognized during metamorphosis: planulae just prior to settlement, ball and filiform stages, immature polyps, and primary feeding polyps. Settlement and metamorphosis of cnidarian planulae involve such changes as ciliary arrest, discharge of nematocytes, secretion of glandular cells, differentiation of cells, and changes in cell and body shape.
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    Journal of Morphology 177 (1983) 
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    Journal of Morphology 177 (1983), S. 1-23 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Both structural and functional changes are observed within the posterior caeca (PC) of Orchestia during the molt cycle. During the intermolt period, there are two segments which are structurally different: a distal segment lined by type I epithelial cells and a proximal segment lined by type II cells. During molting, the PC cells are active in calcium turnover. Calcium is secreted and stored as calcareous concretions in the caecal lumen during the preexuvial period; then during the postexuvial period it is reabsorbed to mineralize the new cuticle. During the preexuvial period, cellular type III differentiates along the whole length of the PC in poster-anterior sequence and functions in ionic calcium secretion, from the basal part to the cellular apex. During the postexuvial period, this cellular type turns into cellular type IV engaged in calcium reabsorption from successive generations of spherites, from the cellular apex to the basal part.The role played by the caecal epithelium during both formation and reabsorption of the concretions was investigated by experiments in which caeca were transplanted to host pericardial cavities or were blocked by causing an abdominal hernia. The main structural characteristic features of cellular type III are as follows: an extracellular network of channels extends from basal to apical ends; microvilli are long and often apically dilated; multivacuolar complexes are localized in extracellular channels and within dilated tips of microvilli before secretion into caecum lumen; bundles of microtubules are oriented in parallel around the luminal orifices of the extracellular network; ribosomes are abundant in cytoplasm. Cellular type III develops progressively from the distal end of the caecum to the proximal one as the preexuvial period advances and concretions form in the caecum lumen.
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    Journal of Morphology 177 (1983), S. 59-68 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The relationships between the size of the articular surface of the mandibular condyle and masticatory muscle size, tooth size, diet, and biomechanical variables associated with mastication were studied by taking 12 measurements on skulls of 253 adult female anthropoid primates, including three to ten specimens from each of 32 species.In regressions of condylar length, width, or area against body weight, logarithmic transformations substantially improve the fit of the equations compared with untransformed data. There is a strong relationship betwden condylar measurements and body weight, with all correlations being .94 or higher. The slopes of the allometric regressions of length, width, and area of the condylar head indicate slight positive allometry with body size.Folivorous primates have smaller condyles than frugivorous primates, and colobines have smaller condyles than cebids, cercopithecines, or hominoids. When colobines are eliminated, the differences between frugivores and folivores are not significant. However, the two species with the relatively largest condyles are Pongo pygmaeus and Cercocebus torquatus, suggesting that there may be a relationship between unusually large condylar dimensions and the ability to crak hard nuts between the teeth.Cranial features having strong positive correlations with condylar dimensions include facial prognathism, maxillary incisor size, maxillar postcanine area, mandibular ramus breadth, and temporal fossa area. These data are interpreted as indicating that relatively large condyles are associated with relatively large masticatory muscles, relatively inefficient mandibular biomechanics, and a large dentition. These relationships support the growing evidence that the temporomandibular joint is a stress-bearing joint in normal function.
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  • 85
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    Journal of Morphology 177 (1983) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 86
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The rapid morphogenetic movements that internalize the transitory larval epithelium and reorient the presumptive adult epidermis during the metamorphosis of the cellularioid cheilostome bryozoan, Bugula neritina, have been examined by light and electron microscopy and analyzed by experimentation with cytochalasin B (CB) and MgC12. The pallial epithelium is gradually drawn out over the aboral hemisphere as the larval ciliated epithelium (the corona and the pyriform organ) involutes. At the end of coronal involution the oral margin of the pallial epithelium constricts and the aboral hemisphere is pulled down against the everted sac. Ultrastructural and experimental evidence indicates that an equatorial contractile ring composed of a temporal alignment of CB-sensitive 5.5 nm microfilaments is responsible for the constriction of the oral margin of the pallial epithelium. This morphogenetic movement, in conjunction with the compression of the aboral hemisphere, juxtaposes the pallial epithelium with the oral epithelium of the everted sac. The pallial epithelium adheres to the neck and wall regions of the everted sac and begins a progressive contraction at its aboral margin, pulling the wall epithelium up over the aboral hemisphere. Ultrastructural examination reveals that the pallial cells contain apical bands of microfilaments and associated vesicles at this stage of metamorphosis. The position and time of appearance of the microfilaments in the pallial epithelium support the hypothesis that they generate the force for wall elevation. Histological and experimental data indicate that the compression of the aboral hemisphere at the umbrella stage and the final retraction of the apical disc are muscle-mediated morphogenetic movements. The constriction of the umbrellar margin and the elevation of the wall epithelium, on the other hand, appear to be caused by two distinct populations of microfilaments that assemble in different regions of the pallial epithelium at specific times during metamorphosis.
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  • 87
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    Journal of Morphology 177 (1983), S. 213-229 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The different elements of the caudal skeleton of the South American catfish genera Nematogenys (Nematogenyinae) and Trichomycterus, Hatcheria, and Bullockia (Pygidiinae) (Siluriformes, Trichomycteridae) show Ontogenetic transformation of the second ural centrum in Trichomycteridae separates the subfamilies Nematogenyinae and Pygidiinae. In the former, the second ural centrum is aligned with the first ural centrum in early stages of ontogeny; it is not fused with the bases of hypurals 3 and 4 in any stage of development. In the Pygidiinae, in contrast, the second ural centrum is connected with the base of hypural 3 from an early stage of development on. One of the most noteworthy features of the Pygidiinae is the epural, a polymorphic element with three or four morphotypes that are species specific.The primitive catfish Nematogenys shows intraspecific variation in the ural centra, segmentation of procurrent caudal rays, and principal caudal ray formulae. Species of Trichomycterus, Hatcheria, and Bullockia are characterized by great intraspecific variability that involves ural centra, the epural, hypurapophyses, and the neural arches of the compound centrum. There is intraspecific variation in the fusion of the hypurals in some species of Trichomycterus.Intraspecific variation of the caudal skeleton of fishes of the family Trichomycteridae involves the presence and frequency of different morphotypes of the epural, neural arch of the compound centrum, fusion of hypurals, and principal caudal ray formulae. Ontogenetic changes of the first and second ural centra, hypurapophyses (with the exception of Nematogenys), and segmentation of procurrent caudal rays (in Nematogenys) are involved also.
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  • 88
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    Journal of Morphology 177 (1983), S. 269-276 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Examination of the topographical anatomy of the stomach complex and intestinal tract of an adult male and a newborn female pigmy hippopotamus (Choeropsis liberiensis) shows that the stomach consists of four chambers, the first three constituting the proventriculus and the fourth the glandular stomach. The proventriculus is made up of a visceral and parietal blind sac opening into a connecting chamber, which in turn opens into the glandular compartment. The walls of the proventricular chambers are covered with villi and non-glandular mucous membrane. The significant difference between the animals is that whereas the connecting chamber of the adult stomach lies transversely deep in the cranial part of the abdomen and connects with the glandular chamber on the right side, that of the newborn lies almost vertically and connects ventrally with the glandular compartment situated on the floor of the abdomen. A groove which in the adult runs more or less horizontally from the cardia through the visceral sac and connecting chambers is aligned almost vertically in the newborn. In the adult the connecting chamber is the largest compartment, but in the neonate the visceral blind sac and the glandular compartment are proportionally larger. Functional aspects of these anatomical differences are discussed in relation to suckling behavior.The intestine consists of a continous tube. There is no caecum; instead the junction between small and large intestine is distinguished by an increase in diameter, a change in epithelial lining, and anastomoses of the jejunal and colic arteries. Large amounts of fat are present in the omentum and mesentery of the neonate.
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  • 89
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    Journal of Morphology 177 (1983), S. 319-328 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cell contacts between follicle cells, and follicle cells and oocytes of egg-laying populations of Helisoma duryi and non-egg-laying populations of H. trivcolvis have been studied. Scanning electron microscopy reveals that four to six follicle cells envelop a single developing oocyte. Thin sections and lanthanum impregnations demonstrate apical zonulae adherentes followed by winding pleated-type septate junctions between follicle cells. Gap junctions and septate junctions have been found between follicle cells and vitellogenic oocytes. Freeze-fracture replicas show relatively wide sinuous rows of septate junctional particles, and nemerous large gap junctional particle aggregates on the P-face between vitellogenic oocytes and follicle cells. Septate and gap junctions between immature or nonvitellogenic oocytes and follicle cells are fewer compared to those in vitellogenic oocytes. Similarly, the junctional complexes are less developed in non-egg-laying H. trivolvis compared to those in egg-laying H. duryi. It is possible that intimate interaction between follicle cells and a developing oocyte is necessary for the maturation of the oocyte. The junctional complexes could be involved in the interaction of the follicle cells and the oocyte, and they must disassemble at the onset of ovulation. Rhombic particle arrays and nonjunctional ridges of particles have been found in the basal part of the oolemma.
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  • 90
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    Journal of Morphology 195 (1988) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 91
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    Journal of Morphology 195 (1988), S. 31-43 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Epithelial-mesenchymal interactions play important roles in morphogenesis, histogenesis, and keratinization of the vertebrate integument. In the anterior metatarsal region of the chicken, morphogenesis results in the formation of distinct overlapping scutate scales. Recent studies have shown that the dermis of scutate scales is involved in the expression of the β keratin gene products, which characterize terminal differentiation of the epidermis on the outer scale surface (Sawyer et al.: Dev. Biol. 101:8-18, '84; Shames and Sawyer: Dev. Biol. 116:15-22, '86; Shames and Sawyer: In A.A. Moscona and A. Monroy (eds), R.H. Sawyer (Vol. ed): Current Topics in Developmental Biology. Vol. 22: The Molecular and Developmental Biology of Keratins. New York: Academic Press, pp. 235-253, '87). Since α and β keratins are both found in the scutate scale and are members of two different multigene families, it is important to know the precise location of these distinct keratins within the epidermis. In the present study, we have used protein A-gold immunoelectron microscopy with antisera made against avian α and β keratins to specifically localize these keratins during development of the scutate scale to better understand the relationship between dermal cues and terminal differentiation. We find that the bundles of 3-nm filaments, characteristic of tissues known to produce β keratins, react specifically with antiserum which recognizes β keratin polypeptides and are found in the embryonic subperiderm that covers the entire scutate scale and in the stratum intermedium and stratum corneum making up the platelike beta stratum of the outer scale surface. Secondly, we find that 8-10-nm tonofilaments react specifically with antiserum that recognizes α keratin polypeptides and are located in the germinative basal cells and the lowermost cells of the stratum intermedium of the outer scale surface, as well as in the embryonic alpha stratum, which is lost from the outer surface of the scale at hatching. The α keratins are found throughout the epidermis of the inner surface of the scale and the hinge region. Thus, the present study further supports the hypothesis that the tissue interactions responsible for the formation of the beta stratum of scutate scales do not directly activate the synthesis of β keratins in the germinative cells but influence these cells so that they or their progeny will activate specific β keratin genes at the appropriate time and place.
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  • 92
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    Journal of Morphology 195 (1988) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 93
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    Journal of Morphology 195 (1988), S. 141-157 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The anatomy of the hyoid apparatus and positional changes of the hyoid bone during mastication and deglutition are described in the New Zealand White rabbit (Oryctolagus cuniculus). A testable model is constructed to predict the range of movement during function of the hyoid, a bone entirely suspended by soft tissue. Frame-by-frame analysis of a videofluorographic tape confirms the accuracy of the prediction through observation of hyoid bone excursion during oral behavior.During chewing, translation of the hyoid bone is diminutive and irregular, lacking a clearly discernible path of excursion. However, some movements of the hyoid occur with regularity. During fast opening, anterodorsal movement of the hyoid is interrupted with an abrupt posteroventral depression when the bolus is moved posteriorly toward the cheek teeth by the tongue. This clockwise rotation (when viewed from the right side) of the hyoid accompanies jaw opening and is reversed (posteroventral movement) for the jaw closing sequence. Lateral movements of the hyoid may be slightly coupled to mandibular rotation in the horizontal plane.The findings suggest that the hyoid bone maintains a relatively static position during the dynamics of chewing. The primary function would be to provide a stable base for the movements of the tongue. Another possible function would be to control the position of the larynx within the pharyngeal cavity. Some characteristic features of the rabbit hyoid apparatus may be consequential to relatively erect posture and a saltatory mode of locomotion.
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  • 94
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    Journal of Morphology 195 (1988), S. 189-204 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The pronephros in juvenile brown trout (Salmo trutta) consists of a large ovoid renal corpuscle and a pair of tubules. The corpuscle is retained for 11 months, after which the glomerulus regresses. The glomerular arteries come directly from the dorsal aorta. The interstitium is permeated with venous blood vessels that arise from the anterior cardinal veins and are closely apposed to the tubules. Two distinct segments of the pronephric tubular system are distinguished by the histological and ultrastructural features of their component cells: (1) a short, transitional neck in which cells change from capsular epithelium to columnar epithelium, typical of tubules; (2) the convoluted segment composed of cells similar to first proximal tubular cells of the opisthonephros with well-formed brush borders, apical vesicles that vary in size and number along this segment, and lysosomes. Pinocytosis and exocytosis are also evident in this segment. The tubular system increases in length and in its convolutions until about week 9, when the opisthonephros develops. Distally each tubule connects with a Wolffian duct, with cells marked by the absence of apical inclusions and the presence of a uniform brush border, numerous mitochondria, and elaborate infolding of the basalar membrane. Nephrostomes, which are often characteristic of pronephroi, are not present. Cells with long cilia are found throughout the tubular system but are most characteristic of the neck and Wolffian-duct segments.
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  • 95
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In anuran amphibians, cranial bones typically first form at metamorphosis when they rapidly invest or replace the cartilaginous larval skull. We describe early development of the first three bones to form in the Oriental fire-bellied toad, Bombina orientalis - the parasphenoid, the frontoparietal, and the exoccipital - based on examination of serial sections. Each of these bones is fully differentiated by Gosner stage 31 (hindlimb in paddle stage) during premetamorphosis. This is at least six Gosner developmental stages before they are first visible in whole-mount preparations at the beginning of prometamorphosis. Thus, developmental events that precede and mediate the initial differentiation of these cranial osteogenic sites occur very early in metamorphosis - a period generally considered to lack significant morphological change. Subsequent development of these centers at later stages primarily reflects cell proliferation and calcified matrix deposition, possibly in response to increased circulating levels of thyroid hormone which are characteristic of later metamorphic stages. Interspecific differences in the timing of cranial ossification may reflect one or both of these phases of bone development. These results may qualify the use of whole-mount preparations for inferring the sequence and absolute timing of cranial ossification in amphibians.
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  • 96
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    Journal of Morphology 195 (1988), S. 313-325 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ultrastructure of the Malpighian tubules of the adult desert locust, Schistocerca gregaria, is described. Male and female adults possess about 233 tubules, which empty proximally into the midgut-ileal region of the alimentary canal by way of 12 ampullae. The tubules vary from 10 mm to 23 mm in length. About one third of them are directed anteriorly, attaching distally at the caeca, while the remainder are directed posteriorly, attaching to other tubules, the rectum or large tracheal trunks adjacent to the hindgut. The Malpighian tubules from all locations examined consist of three ultrastructurally distinct regions: proximal, middle, and distal, referring to their position relative to the midgut. All cell types possess ultrastructural features characteristic of ion transporting tissue, i.e., elaboration of the basal and apical membranes and a close association of these membranes with mitochondria. The distal and proximal segments are short (1.5-1.7 mm) and heavily tracheated, and each is composed of a single, distinct cell type. The middle region is the longest segment of the Malpighian tubule and is composed of two distinct cell types, primary and secondary. Both cell types are binucleate. The more numerous primary cells have large nuclei, contain laminate concretions in membrane-bound vacuoles, and possess large microvilli that contain mitochondria. The secondary cells are smaller and possess smaller nuclei. The microvilli are reduced and lack mitochondria. Secondary cells do not contain laminate concretions. The possible compartmentalization of ion and fluid transport function based on segmentation in the Malpighian tubules is discussed.
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  • 97
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    Journal of Morphology 196 (1988), S. 107-116 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The morphology of the middle ear region including the basicranium and quadrate of tinamous is compared among ratites and flying birds belonging to the Procellariiformes, Sphenisciformes, Pelecaniformes, and Ciconiiforms. The middle ears of tinamous and ratites share a number of important characters including absence of a separate foramen for the glossopharyngeal nerve; eustachian tube, carotid artery, and stapedial artery encased in bone; and a metotic process with vascular canals or notches. Outgroup analysis confirms these characters as synapomorphies. These data support the position that the Tinami and Ratiti form a monophyletic assemblage.
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  • 98
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    Journal of Morphology 196 (1988), S. 53-72 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The colonial marine bryozoan Membranipora membranacea produces a planktotrophic cyphonautes larva that is encased by a triangular bivalved shell. Following a relatively long free-swimming phase, the cyphonautes larva settles and undergoes a dramatic metamorphosis to become the sessile progenitor of the colony, referred to as the ancestrula. This paper examines the initial morphogenetic movements of metamorphosis that transform the cyphonautes larva into an incipient ancestrula. At the onset of metamorphosis, contractions of the striated median muscles situated along the anterior and posterior margins of the larva cause a retraction of the larval apical organ and a centripetal movement of the anterior and posterior ends of the larva. Concurrently, the ciliated corona at the base of the larva is pulled within the shell by contractions of the striated lateral muscles. As the larva assumes a more spherical shape, the posterior margins of the shell are spread apart, and the internal sac is everted. Eversion of the sac is apparently achieved by contractions of the lateral muscles that cause a buckling of the shell in the apical-basal direction. The neck region of the everted sac secretes adhesive granules that attach the larva to the substratum. Subsequently, contractions of the nonstriated sac muscles fold the valves of the shell over each other and draw the larva toward the substratum. The initial events of metamorphosis that culminate in the attachment and flattening of the larva are completed in 10-15 seconds. In the subsequent few minutes, the lateral edges of the everted sac fuse with the neighboring margins of the aboral epithelium underlying the shell and thus form the fully sealed body wall of the incipient ancestrula.
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  • 99
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    Journal of Morphology 196 (1988), S. 127-136 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Available evidence provides little support for a recent proposal that the term “trophoblast” be applied solely to eutherian mammals. Arguments for such a restricted usage are based on a dichotomous interpretation of therian reproduction that underestimates the developmental, structural, and functional diversity of trophoblastic tissues occurring within the infraclass Eutheria. The occurrence of developmental patterns that are phenotypically intermediate between those of commonly studied eutherians and metatherians suggests that blastocyst development is not fundamentally different in marsupials and eutherians.The trophoblast of marsupials accomplishes most or all of the major functions of the eutherian trophoblast, including maternal-fetal physiological exchange, implantation, contribution to placental membranes, steroid metabolism, and possibly, immunological protection of the conceptus. Furthermore, application of the term “trophoblast” to marsupials is consistent with present and past usage, as well as with the original definition and etymological derivation of the term. Therefore, we recommend that the term “trophoblast” continue to be applied in a functional-morphological sense to the appropriate extraembryonic tissues of marsupials. Such use of functional (rather than taxonomic) criteria for application of this term avoids biasing interpretations of mammalian reproductive evolution.
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  • 100
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    Journal of Morphology 196 (1988), S. 195-204 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The primary and secondary elements of the cephalic vascular system in some sea snakes are similar to those of the generalized ophidian pattern. The three species examined in this study revealed only minor variations in vascular morphology; these variations appear to be correlated with myological differences among the three species. For example, in Hydrophis melanocephalus it appears that the depressor mandibulae artery is displaced by the cranially expanded insertion of the semi-spinalis and spinalis muscles. A preliminary hypothesis is put forth that explains the apparent constancy of the cephalic vascular system of ophidians in terms of possible constraints due to cranial kinesis.
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