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  • 1985-1989  (1,527)
  • 1880-1889
  • 1985  (1,527)
  • Life and Medical Sciences  (1,389)
  • Atomic, Molecular and Optical Physics  (138)
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  • 1985-1989  (1,527)
  • 1880-1889
Year
  • 101
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 28 (1985), S. 663-663 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 102
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    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 28 (1985), S. 665-686 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper serves a twofold purpose. First, Löwdin's inner projection in both nonperturbative and perturbative forms is applied to the quartic anharmonic oscillator. Inner projection with perturbation theory yields rational approximations to Brillouin-Wigner-type perturbation expansions. These lower bounds are compared with [N - 1, N] Padé approximants to the Rayleigh-Schrödinger perturbation series for this problem. These Padés are also expressible as the even convergents, w2N, of a Stieltjes-type continued fraction. The latter representation has certain advantages with respect to its Padé counterpart. Inner projection without perturbation theory provides significantly better results than the perturbative version. The application of inner projection techniques to a perturbed hydrogen atom is not straightforward. The usual problems associated with the continuum spectrum of hydrogen are present. By means of a nonunitary “tilting” transformation associated with the Lie group SO(4, 2), these problems may be bypassed. In the SO(4, 2)-reformulated eigenvalue problem, a reinterpretation of the basic variables, as developed by Silverstone and Moats, yields a new Hamiltonian that permits direct use of the inner projection method. This method has been applied to the ground state of the hydrogen atom in a magnetic field, using both four- and eight-dimensional basis manifolds. This represents the first application of inner projection to this problem.
    Additional Material: 7 Ill.
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  • 103
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    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 28 (1985), S. 741-756 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A comparative study of quasirelativistic equations used in atomic structure calculations has been performed. A uniform derivation of all the equations is presented, and some of their specific features are discussed in detail. Electron density distributions, orbital energies, and expectation values of rn obtained with different methods are compared with the ones resulting from the Schrödinger and Dirac equations. The most accurate are found to be the equations of Wood and Boring and of Barthelat, Pelissier, and Durand. (They reproduce almost exactly the Dirac electron densities and expectation values.) The simplest, though least accurate, equation is proposed by us. It gives the relativistic energy corrections with about 6% accuracy and retains exactly the form of the nonrelativistic Schródinger equation. Consequently, its application in analytical SCF-CI calculations does not require any additional integral calculation.
    Additional Material: 4 Ill.
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  • 104
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    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 27 (1985), S. 59-70 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The representation matrices of the unitary group generators Ek1 are equivalent to the representation matrices of cyclic permutations (k, k ± l, …, l ∓ 1, l). A method is presented for simultaneous computation of matrices corresponding to all different generators at a cost of less than one multiplication per nonzero element. The number of operations necessary for calculation of individual matrices for single generators or for products of two generators is at most proportional to the number of matrix elements of the final matrix. This approach eliminates the need to store the representation matrices in CI calculations.
    Additional Material: 4 Ill.
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  • 105
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    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 27 (1985), S. 1-10 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio molecular orbital calculations using a 3-21G basis set have been used to optimize geometries for pyrrole, CH3(X)CCH2, CH3(H)CCHX (both cis and trans), c-C3H5X, and CH2CHCH2X, where X is CN and NC. In all the alkenyl derivatives methyl groups are found to adopt the conformation in which the methyl hydrogen eclipses the double bond. 6-31G*∥3-21G level calculations show the alkenyl cyanides to be of similar energy to pyrrole, but the isocyanides are ∼20 kcal mol-1 higher in energy. For both substituents the cyclopropyl derivatives are higher in energy by ∼10 kcal mol-1. At the 6-31G* level ring strain is 27.7 kcal mol-1 for the cyanide and 30.6 kcal mol-1 for the isocyanide. Data on the relative energies of RCN and RNC are compared when R is (i) a saturated hydrocarbon, (ii) an unsaturated hydrocarbon, (iii) an α-carbenium ion, (iv) an allyl cation, and (v) an α-carbanion.
    Additional Material: 2 Ill.
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  • 106
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    International Journal of Quantum Chemistry 27 (1985), S. 103-103 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 107
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    International Journal of Quantum Chemistry 27 (1985), S. 115-133 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electronic absorption spectra of some benzohydroxamic acids have been analyzed and interpreted using the results of molecular-orbital calculations. Charge density distributions, dipole moments, and the extent of delocalization of the MOS were used to interpret the observed solvent effects. Comparison between the spectra of benzohydroxamic acids and that of simple amides led to conclusions regarding the structural differences between the two classes of compounds.
    Additional Material: 12 Ill.
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  • 108
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    International Journal of Quantum Chemistry 27 (1985), S. 109-113 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A semianalytic scheme is proposed for the evaluation of Brillouin zone (BZ) double integrals such as are met in the evaluation of Compton profiles (CPS) and the angular distribution of annihilation photons (ADAPS) obtained in single-slit positron annihilation experiments. The difficulty that arises due to the jump discontinuities in the momentum density at the generalized Fermi surfaces (FS +HMC), pF = kF + g, where kF is the electron Fermi momentum vector and g is a reciprocal lattice vector, is addressed.
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  • 109
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    International Journal of Quantum Chemistry 27 (1985), S. 167-171 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Following a paper drawing up a matrix form of the time-dependent Hartree-Fock equations which allow the calculation of the nth harmonic generation, we establish the matrix form of the hyperpolarizability tensor. In case of linear polarization, we show that, if the ground-state orbitals are real, so are the perturbed ones. This involves an easy expression of the hyperpolarizability tensor.
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  • 110
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    International Journal of Quantum Chemistry 27 (1985), S. 203-218 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fick's law of diffusion has been generalized to include kinetic processes, the transport term of the Boltzmann equation, and nonlocal interaction processes. It is shown that the collision interaction term can be obtained by the introduction of a quantum stochastic potential equation. Some approximations of a nonlocal Boltzmann equation can be solved exactly. The solutions can be applied to problems of molecular pattern in biology.
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  • 111
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    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 27 (1985) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 112
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    International Journal of Quantum Chemistry 27 (1985), S. 273-280 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hyperspherical coordinates and a generator coordinate representation are employed to find a simple form of the kinetic energy for a general three-particle problem. An expression is developed for the determination of adiabatic hyperangular states in a local potential using the finite element method.
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  • 113
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    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 27 (1985) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 114
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    International Journal of Quantum Chemistry 27 (1985), S. 393-406 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The local behavior of several approximate kinetic energy functionals is analyzed, for the case of free atoms and ions, by comparison with the local kinetic energy of Hartree-Fock theory. The atomic electron densities used are, in all cases, Hartree-Fock electron densities. The kinetic energy functional obtained by the gradient expansion method (with a small number of terms) is, locally, not very accurate, but its integrated value is fortuitously accurate, due to a strong cancellation of errors. Functionals which have the Weizsäcker term tw = (Δ ρ)2/8ρ as a key ingredient are more accurate locally. The explicit incorporation of the shell structure and nonlocal density effects into the kinetic energy functional leads to the best results. The motivation for this work is that only a kinetic energy functional with an accurate local behavior will give good electron densities on solution of the Euler equation derived from it.
    Additional Material: 4 Ill.
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  • 115
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    International Journal of Quantum Chemistry 27 (1985), S. 427-437 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mulliken's atomic charges (MC) and potential derived (PD) point charges obtained from STO-3G wave functions are used to study the electrostatic interaction energies for a series of representative hydrogenbonded complexes. The results of the above-mentioned models are compared with the more accurate results of segmental multipole moment (SMM) expansion, and it is shown that the PD model is superior to the Mc model. The results of PD model are shown to be well correlated with the results of SMM expansion technique. Results of our calculations using 6-31G and 6-31G** PD charges are also reported here. Electrostatic interaction energies obtained using 6-31G** PD charges are compared with the 6-31G** SCF interaction energies available for the nine hydrogen-bonded dimers of ammonia, water, and hydrogen fluoride and a good con-elation between the two is shown. The interrelationship between the results of different basis sets are also examined for the PD point-charge model. The electrostatic interaction energies obtained using STO-3G PD model are shown to be well correlated to the results of 6-31G and 6-31G** PD models.
    Additional Material: 6 Ill.
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  • 116
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    International Journal of Quantum Chemistry 27 (1985), S. 475-479 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hartree-Fock energies are reported for about 20 low-lying quartet states of B III. A comparison with experimental transition wavelengths shows that Hartree-Fock energies can be helpful to rule out erroneous assignments but that, in general, their accuracy is insufficient for definite confirmation of proposed assignments.
    Additional Material: 2 Tab.
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  • 117
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    International Journal of Quantum Chemistry 27 (1985), S. 495-500 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Simons has previously derived a simple formula for the linewidth Γ of a resonance state in the continuum from real stabilization graphs under the assumption that the energy curves vary almost linearly near the points of avoided crossing. This formula is now rederived without this restricting assumption under the condition that Γ is still small.
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  • 118
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    International Journal of Quantum Chemistry 27 (1985), S. 559-565 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The double-zeta atomic functions are characterized by the nuclear charge z of the two-electron atomic system. The Hartree-Fock total energies and the corresponding orbital energies are calculated using various atomic wave functions for the helium isoelectronic sequence. The expectation values rn of various wave functions are also examined. It is found that the accuracy of our one-parameter double-zeta functions corresponds to the accuracy of the usual five-parameter double-zeta functions.
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  • 119
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    International Journal of Quantum Chemistry 27 (1985), S. 653-664 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new computation procedure for direct calculation of the density matrix in the LCAO version of the restricted Hartree-Fock-Roothaan open-shell theory is analyzed. It is proved that the procedure is quadratically convergent and stable to the round-off errors independently of the Fock operator spectrum. The dependence of the limit matrix of the initial matrix is examined.
    Additional Material: 2 Ill.
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  • 120
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    International Journal of Quantum Chemistry 27 (1985), S. 769-780 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A consistent propagator approximation, denoted as the excitation propagator, is introduced. This propagator describes excitations between N-particle states and its approximation has properties required of consistent random phase approximation schemes. Several properties of this propagator are explored when based on a generalized antisymmetrized geminal power wavefunction. How singularities in the metric occur and how to remove them is discussed in detail. The excitation propagator is also contrasted with the principal (polarization) propagator.
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  • 121
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    International Journal of Quantum Chemistry 27 (1985), S. 743-768 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The definition of a molecular property as a derivative of the electronic energy with respect to one or more applied perturbations is reviewed. The explicit enumeration of terms entering the derivative formulas is performed by considering in turn the various parameter spaces on which the energy and wave function depend. After deriving general expressions for first, second, and third derivatives for different types of perturbation, the parameter spaces involved in MCSCF and CI cases are identified and used to obtain expressions for the first and second derivatives. An example of an MCSCF third derivative is also given. In addition, the various equation systems defining the perturbed wave functions in each order are derived. Some attention is given to the efficient computer implementation of derivative calculations, and the present work is compared with that of other authors.
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  • 122
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    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 28 (1985) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 123
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio MODPOT/VRDDO/MERGE calculations have been carried out for all the different position isomers of nitrocubane from mononitrocubane through octanitrocubane for a perfect symmetrical cubic cubane skeleton and for mononitrocubane through septanitrocubane for the almost cubic experimentally determined cubane skeleton. These calculations were carried out with our own rapid efficient ab initio programs which also incorporate a number of desirable computational strategies for calculations on large molecules. The skeletal total overlap population of the cubane skeleton (a theoretical index we showed years ago to be sensitive and predictive of stability of energetic molecular frameworks) indicates that successive nitration seems to increase the stability of the cubane skeleton. Successive nitration also seems to increase the total overlap population of the C—NO2 bond. There are subtle differences depending on the exact positional isomer for a constant number of nitro groups - but the overall trend is definite. We have also generated electrostatic molecular potential contour (EMPC) maps around these nitrocubanes. These maps are indicative of preferred positions of electrophilic and nucleophilic attack as a function of the number of nitro groups or their positions. These EMPC maps can also indicate, to a first approximation, a limit on how close these molecules may be able to approach each other in a crystal.
    Additional Material: 3 Ill.
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  • 124
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    International Journal of Quantum Chemistry 28 (1985) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 125
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    International Journal of Quantum Chemistry 28 (1985), S. 181-202 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The well known one-to-one correspondence between the eigenstates of the total spin for a system of spin-½ particles and irreducible representations of the symmetric group with up to two rows in the Young shape is the basis of interesting formal developments in quantum chemistry and in the theory of magnetism. As an explicit manifestation of this correspondence the class operators of the symmetric group are demonstrated to be expressible in terms of the total spin operator. This correspondence does not hold for higher elementary spins. The extension to arbitrary spin is investigated using Schrödinger's generalization of the Dirac identity, which expresses the transpositions in terms of two-particle spin operators. It is shown that additional operators, which for σ = ½ reduce to the total spin operator, are needed for a complete classification. Some aspects of the formalism are developed in detail for σ = 1. In this case a classification identical with that provided by the irreducible representations of the symmetric group is obtained in terms of the eigenstates of two commuting operators, one of which is the total spin operator.
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  • 126
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    International Journal of Quantum Chemistry 28 (1985), S. 239-244 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Based on the literature values, the pK1 and pK2 for pyrazine and its six methyl derivatives, the correlation with electron density on the nitrogen atoms N1 and N4 was found. The effect of methyl group was proved to be additive. The total electron density, π-electron density, and dipole moments for compounds under study were determined by the CNDO/2-MO method.
    Additional Material: 2 Ill.
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  • 127
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    International Journal of Quantum Chemistry 28 (1985), S. 451-457 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have studied the effect of Hubbard interaction on solitonic excitations in the polymer trans-polyacetylene. These excitations are modeled using the Su, Schrieffer, and Heeger (SSH) Hamiltonian. Within this framework, we have calculated the full configuration interaction and restricted Hartree-Fock energies of solitonic excitations in trans-polyacetylene chains with 4-10 carbon atoms. These results are extrapolated to longer chains, and it is shown that the correlation energy for these chains approaches 3%. Thus, our calculations provide a justification, hitherto absent, of the accuracy of the Hartree-Fock calculations reported in the literature.
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  • 128
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    International Journal of Quantum Chemistry 28 (1985), S. 499-516 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The collisional exchange of energy between He atoms and a strongly polar diatomic, the LiH target, has been studied theoretically over a range of relative energies that had been previously sampled by experiments with molecular beams. The relative importance of the rotational and/or vibrational channels is examined by studying in detail the effect of the interaction via a model potential coupling parameter. The different behavior exhibited by differential cross sections (total and partial inelastic) is also analyzed in terms of the strength and shape of the interaction anisotropy.
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  • 129
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    International Journal of Quantum Chemistry 28 (1985), S. 517-523 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Model ring systems 2′-deoxy-2′-fluororibofuranose and deoxyribofuranose have been investigated using ab initio calculations with the 3-21G basis set. The energy barrier to pseudorotation between the N and S states has been evaluated for the three preferred orientations of the (3′)-OH group. Positions of the energy minima and the transition state have been optimized with respect to the (3′)-OH orientation. The barrier to pseudorotation of 2′-deoxy-2′-fluorofuranose is high and asymmetrical (ΔEN→S ≈ 20, ΔEN←S ≈ 8 kJ/mol), whereas the barrier of 2′-deoxyfuranose is lower and almost symmetrical (ΔE ≈ 11-12 kJ/mol). The results obtained show that the preferred configuration of the 2′-deoxy-2′-fluororibo-furanose (N state) is stabilized by an internal O(3′)-H…F interaction in accord with the crystallo-graphic data.
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  • 130
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    International Journal of Quantum Chemistry 28 (1985), S. 553-564 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The large vibrational inelasticity observed in proton-O2 scattering at collision energies of ∼10.0 eV and for various angular distributions below the rainbow region is examined in terms of SCF adiabatic potential energy surfaces which exhibit strong O2+ “character” within a specific range of relative distances between colliding partners. The possibility for this O2 distortion during encounters with protons to be responsible for the unusually large inelasticity is discussed and the time factors that are likely to play an important role during the dynamics are also considered and analyzed.
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  • 131
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    International Journal of Quantum Chemistry 28 (1985), S. 631-639 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Atom-metal surface overlap integrals are of utmost importance in surface energy calculations. Direct numerical evaluation of these triple integrals can be very time-consuming. However, we have developed an exact algebraic expression, where formulas for the coefficients are given for both the general case and the special case where the parallel wave vector is zero. Some numerical examples of the overlap for H on Al are given.
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  • 132
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    International Journal of Quantum Chemistry 28 (1985), S. 661-661 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 133
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    International Journal of Quantum Chemistry 28 (1985), S. 691-701 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A multiconfigurational variation of moments (MCM) is presented to determine correlated orbital energies. Appropriate multiconfigurational one-particle operators are introduced starting for closed-shell systems from the restricted Hartree-Fock (RHF) scheme and for open-shell system from the unrestricted Hartree-Fock (UHF) scheme. The advantage of these operators is the linear form of the correlation energy in the configuration interaction (CI) coefficients. They obey HF analogous pseudoeigenvalue equations and are therefore a generalization of the HF operator. In principle, the scheme can be extended to a multiconfiguration self-consistent field (MCSCF) procedure for moments. In contrast to the SCF formalism they allow an orbital description of degeneracy and quasidegeneracy of the highest occupied (HOMO) and lowest unoccupied (LUMO) molecular orbital. With these operators, funnels of thermally forbidden Woodward-Hoffman reactions, as well as dissociations, can be described in a physically meaningful fashion by orbitalcorrelation diagrams.
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  • 134
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    International Journal of Quantum Chemistry 28 (1985), S. 731-740 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular-orbital calculations, using the INDO procedures, were carried out on the tautomers of 1, 2, 4-triazole and its benzo-derivative as well as on 1, 2, 5-oxadiazole and its benzo-derivative. Calculations of the transition energy as well as the dipole moment helped to predict the predominant tautomer in an equilibrium mixture. The correspondence between the calculated and observed data is satisfactory. The results of calculations indicated some differences in the electronic structures of the tautomers of a compound.
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  • 135
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    International Journal of Quantum Chemistry 28 (1985), S. 773-796 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio configuration interaction calculations are reported on the lowest quintet, triplet, and singlet states of FeII(P). Due to the large number of states found, a catalog of the low-lying states is presented. Novel triplet and quintet charge-transfer states are reported as low as 1.3 eV. These states are d5 (S = 5/2) on the iron low-spin-coupled to the radical anion excited porphyrin ring (S = 1/2 or 3/2). Oscillator strengths originating from each of three low-energy triplet states are reported.
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  • 136
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    International Journal of Quantum Chemistry 28 (1985), S. 581-591 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some accurate results on the length dependence of the excitation energies from the ground state to ionic excited states in the Hubbard model of linear polyenes are obtained based on the method of Lieb and Wu. To this end, it is first shown that singly ionic excited states with “plus” alternancy symmetry in the Hubbard model are described by the wave functions in which the two electron operator [∑n=1N(-)nCnα+Cnβ+] is acted on (N - 2)-electron covalent eigenstates. Then by solving the Lieb-Wu equations the exact excitation energies of the lowest ionic state, which corresponds to the E1+ state in this model, are calculated for systems with up to 50 electrons. The result, together with a correction for the end effect, indicates that the excitation energies do not decrease as 1/N but converge to the limiting value more rapidly when the number of electrons N becomes large.
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  • 137
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    International Journal of Quantum Chemistry 28 (1985), S. 593-601 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new procedure for construction of spin-adapted DIM bases is described. The procedure is based on the direct diagonalization approach, is quite general, and seems to be especially suited for computer implementation. The structure of the bases obtained by the procedure appears to be favorable for performing symmetry operations necessary in setting up the Hamiltonian matrices in semiempirical applications of the DIM method.
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  • 138
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    International Journal of Quantum Chemistry 28 (1985), S. 641-648 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hybrid orbitals of tetrahedral oxy-ions containing some d character have been calculated by maximum overlap method. The d characters of hybrid orbitals increase in the order of SiO44-, PO43-, SO42-, ClO4-, and decrease in order of GeO44-, AsO43-, SeO42-, BrO4-. The bond strengths are also obtained for these ions. The hybrid Orbital of VO43-, CrO42-, and MnO4- are of the type d3s as the result of calculation.
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  • 139
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    Journal of Morphology 183 (1985), S. 293-299 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Use of the term “trophoblast” in descriptions of therian (marsupial and eutherian) mammals has caused confusion because of misinterpretations of blastular homologies and because of imprecise application in functional versus ontogenetic-phylogenetic senses. Marsupials follow the plan of early development characteristic of noneutheian amniotes. Eutherians, in contrast, are unique in the early determination of presumptive embryonic versus extraembryonic cells through formation of inner cell mass versus trophoblastic (or trophectodermal) tissues, respectively. No cellular unit of the eutherian blastula is recognizable unequivocally as the homologue of a specific part of the protodermal marsupial blastula; progressive deletion of innovative but phylogenetically older ontogenetic steps probably figured importantly in the evolution of eutherian early embryogenesis. Because of marked differences in mode of formation and in cellular fates, homology of the blastocoel between marsupials and eutherians is questioned. It is suggested that use of the term “trophoblast” (1) be restricted to eutherians in discussions of ontogenesis or phylogenesis, and (2) be deemphasized in the functional sense (i.e., fetal-maternal exchanges) for marsupials, in favor of the more appropriate tissue terms of “choriovitelline” and “chorioallantoic” membranes. Integral to the origin of the eutherian style of embryogenesis was the evolution during Cretaceous time of neomorphic, extraembryonic tissues (i.e., trophoblast) having physiological properties that allowed the unique combination of (1) intimate apposition of fetal and maternal tissues and circulatory systems, along with (2) sustained, active morphogenesis. Marsupials have not achieved such a combination.
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  • 140
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    Journal of Morphology 184 (1985), S. 1-22 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Males of Euphydryas editha (Lepidoptera: Nymphalidae) need their antennae to mate successfully, but females do not. Antennal structure was investigated in the hope of explaining this functional dimorphism, which is opposite to that in other butterflies (e.g., Myers, '68; Grula and Taylor, '80). No external differences between the sexes were observed with electron microscopy. There are four types of antennal sensilla: the spine, which acts mainly as a mechanoreceptor, shallow dish hairs and hidden hairs, which are chemoreceptors, and a whiplike sensillum of uncertain function. The internal morphology of male and female antennae differs in several respects which may relate to functional differences. The mating systems of butterflies are discussed briefly to explain our results and those of others.
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  • 141
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    Journal of Morphology 184 (1985), 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: Lifelike models of the oscillating legs treated as three-segment systems show the course of kinetic and potential energy over the locomotor cycle for a cheetah, pronghorn, jackrabbit, and elephant running at speeds approaching their maxima. The models can be adjusted to eliminate differences among the animals in time intervals, mass or length of limb, and joint angles. This facilitates analysis of the influence on total energy of each of these variables and of the distribution of mass among leg segments. Fast-cycling legs of the carnivore type have significantly more energy than those of the hoofed type. This may contribute to the lesser endurance that is usual for carnivores that hunt using a high-speed dash.
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  • 142
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    Journal of Morphology 184 (1985), S. 33-40 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The size and microscopic structure of the spleen of the migratory pied flycatcher (Ficedula hypoleuca) show marked changes during the reproductive cycle. Upon the spring return to their northern breeding sites, the birds have a small spleen with little lymphoid activity and a poorly developed red pulp. During the breeding period the volume of red and white pulp increases, the number and distinctness of lymphoid follicles (germinal centres) in the white pulp increase, and groups of cells with intensely basophilic cytoplasm, probably B cells (plasma cells), appear. The findings suggest that the immune system of the adult pied flycatcher is activated during periods when it is bound to the nest.Young flycatchers beginning their autumn migration also show a marked increase of lymphoid activity in the spleen.
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  • 143
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    Journal of Morphology 184 (1985), S. 61-73 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Innervation of the early pelvic fin bud in the trout embryo involves four nerves. Electron microscopy discloses axons in the mesodermal mesenchyme and in the epidermis of the bud as early as stage I of the development of the pelvic fins. Sensory axons alone penetrate the epidermis. Unmyelinated axons invade the pelvic fin territory before the bud is obvious on the abdomen. Schwann cells occur in the vicinity of the ventral edge of the myotomes and later in the core of the bud and in subepidermal regions. Consequently, the nerve fibers are present early in the development of the pelvic fin bud of the trout embryo. Although the role of these axons is unknown, it is speculated that they play a role in development. Our results are discussed in the light of data available in the literature dealing with the development of tetrapod appendages.
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  • 144
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    Journal of Morphology 184 (1985), S. 51-59 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A morphological and cytometric analysis of the adult fat body cells and oenocytes was made on sections of abdomens from immature, mature and senescent Drosophila melanogaster of both sexes. There are about 18,000 fat body cells in abdomens of female and mature male flies. Immature and senescent males have about 12,000 and 15,000 cells, respectively. The size of the cells is almost the same for immature flies of both sexes and increases about six-fold to approximately 2600μm2, so that mature flies of both sexes have equivalent amounts of fat body tissue. The proportions of lipid, glycogen, and background cytoplasm of fat body cells also remain relatively constant throughout adult life, but dense, proteinaceous granules are observed in cells of senescent flies. The amounts of cellular components change dramatically due to change of cell size with age; the amount of lipid shows the greatest sexual difference with about 2 × more in the females at all stages studied. The oenocytes number about 6,000 in the abdomens of all but immature male flies, which have approximately 4,000. Although the cells of both sexes triple in size to about 700 μm2, the oenocytes of males reach maximum size earlier than those of females. The major features of oenocytes appear to be dense background cytoplasm, putative lipid droplets found only in mature flies, and pigmented granules first seen in the cells of mature flies which accumulate with age to 33% of the cytoplasm. The number of cells and their anticipated capacity for protein synthesis is discussed in relation to the production of yolk protein precursors.
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  • 145
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    Journal of Morphology 184 (1985), S. 41-49 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Upon fertilization, the zebrafish egg undergoes marked physiological and structural changes, one of which involves blastodisc formation. Before fertilization, yolk globules are rounded and the endoplasm extends throughout the oocyte. During blastodisc formation, the yolk globules become angular and the endoplasm is restricted to streamers among the yolk globules. The streamers are oriented in an anterior-posterior axis of the egg. During blastodisc formation the cytoskeleton consists of an extensive array of filamentous structures of variable width in both the cortex as well as within elongate endoplasmic streamers. Although the filamentous components in the cortex and endoplasmic streamers probably include both microfilaments and microtubules, frequently they are somewhat wider than the usual dimensions, and possible reasons for this are suggested. From their arrangement in both the cortex and endoplasm, it seems likely that the components of the cytoskeleton (e.g., microfilaments and microtubules) may provide, through contraction, the major force responsible for the streaming of the endoplasm into the forming blastodisc. It is assumed that the surface tension of the vegetal hemisphere exceeds that of the animal hemisphere, thus forcing, through differential contraction, the endoplasm to flow in the direction of the forming blastodisc. No distinct barrier between the yolk and forming blastodisc was observed. The compressed condition of the larger and many-sided yolk globules could prevent their movement into the blastodisc. Scanning electron microscopy is limited in the resolution with which it can depict the cytoskeleton, but nonetheless it provides useful information about structural interrelationships.
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  • 146
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    Journal of Morphology 184 (1985), S. 99-100 
    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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  • 147
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    Journal of Morphology 184 (1985), S. 111-120 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The mature spermatozoon of Admetus pomilio is a spherical cell containing nucleus and tightly coiled flagellum. In early spermatids the Golgi apparatus forms the acrosomal vesicle and at the opposite side the distal centriole gives rise to the axonemal complex of the sperm tail. As the nucleus elongates, chromatin forms twisted filaments and the spermatid nucleus takes on a helical form. Microtubules are juxtaposed with the nucleus envelope, which is separated from a central chromatin mass by an electron lucid region. A long perforatorium, located on the border of the chromatin mass, runs helically in the nucleus from the centriolar region to subacrosomal space. During tail elongation, the anterior part of the axoneme is surrounded by a long, spiral mitochondrial sheath. In the late spermatid, chromatin filaments appear twisted and become aggregated. The nucleus and flagellum undergo further contortions in which the nucleus coils and the flagellum winds up into the body of the cell and coils in a regular fashion. The mitochondrial sheath surrounds about 2/3 of the 9 + 3 axoneme. These features of spermatid ultrastructure resemble those in the primitive Liphistiomorpha.
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  • 148
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    Journal of Morphology 184 (1985), S. 135-154 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The dorsal ventricular ridge is a subcortical structure receiving sensory information from the thalamus in reptiles. In the red-eared turtle, Pseudemys scripta elegans, it contains four cytoarchitectonic areas each characterized by distinct thalamic projections. This is an electron microscopic study of one of these, the dorsal area, which receives its thalamic input from the tectorecipient nucleus rotundus. It contains four concentric zones, internal to the ependymal zone, each of which is distinguished by the distribution of spiny and aspiny neurons.The ependymal zone of dorsal area contains tanycytes whose tails extend into zones 2 and 4. Synapses, usually with asymmetric junctional complexes and round synaptic vesicles, occur on these processes. Zone 1 neurons have fusiform somata and dendrites that parallel the ventricular surface. Their cytoplasm contains rough endoplasmic reticulum located primarily in Nissl bodies, lipofuchsin granules, multivesicular bodies, extensive arrays of Golgi apparatus, and large numbers of mitochondria. Synapses occur mainly on dendritic spines and shafts of zone 1 neurons and less frequently on somata. The majority have round vesicles and asymmetric junctional complexes. In contrast to those in zone 1, neurons in zones 2 and 4 have large amounts of rough endoplasmic reticulum, giving their cytoplasm an electron-dense quality. Synapses occur mainly on spines and shafts of zone 2 and 4 neurons. As in zone 1, the majority have round synaptic vesicles and contain asymmetric junctional complexes. Zones 2 and 4 contain clusters of neurons distributed among isolated neurons. The clusters are larger and less frequent in zone 2. Protoplasmic and fibrous glial processes, axon boutons, dendrites, and axon fascicles surround the neuron clusters. Though less numerous, the same structures also occur inside the clusters. Most synapses inside the clusters have round synaptic vesicles, asymmetric junctional complexes, and occur mainly on spines. Some neurons in clusters have somata whose plasma membranes are in direct apposition. In contrast to dorsal ventricular ridge in snakes, no specialized intercellular contacts were seen between somata in clusters.
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  • 149
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    Journal of Morphology 184 (1985) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 150
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    Journal of Morphology 184 (1985), S. 215-230 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Tooth primordia at early stages of mineralization in the sharks Negaprion brevirostris and Triaenodon obesus were examined electron microscopically for evidence of ameloblastic secretion and its relation to calcification of the enamel (enameloid) layer. Ameloblasts are polarized with most of the mitochondria and all of the Golgi dictyosomes localized in the infranuclear end of the cell toward the squamous outer cells of the enamel organ. Endoplasmic reticular membranes and ribosomes are also abundant in this region. Ameloblastic vesicles bud from the Golgi membranes and evidently move through perinuclear and supranuclear zones to accumulate at the apical end of the cell. The vesicles secrete their contents through the apical cell membrane in merocrine fashion and appear to contribute precursor material both for the basal lamina and the enameline matrix. The enamel layer consists of four zones: a juxta-laminar zone containing newly polymerized mineralizing fibrils (tubules); a pre-enamel zone of assembly of matrix constituents; palisadal zones of mineralizing fibrils (tubules); and interpalisadal zones containing granular amorphous matrix, fine unit fibrils, and giant cross-banded fibers with a periodicity of 17.9 nm. It seems probable that amorphous, non-mineralizing fibrillar and mineralizing fibrillar constituents of the matrix are all products of ameloblastic secretion. Odontoblastic processes are tightly embedded in the matrix of the palisadal zones and do not appear to be secretory at the stages investigated. The shark tooth enamel layer is considered homologous with that of other vertebrates with respect to origin of its mineralizing fibrils from the inner dental epithelium. The term enameloid is appropriate to connote the histological distinction that the enamel layer contains odontoblastic processes but should not signify that shark tooth enamel is a modified type of dentine. How amelogenins and/or enamelins secreted by ameloblasts in the shark and other vertebrates are related to nucleation and growth of enamel crystallites is still not known.
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  • 151
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    Journal of Morphology 184 (1985), S. 231-252 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Light and electron microscopy of the pacemaker ganglion of the scorpion heart indicate that it is about 15 mm long and 50 μm in diameter and extends along the dorsal midline of the heart. The largest cell bodies (30-45 μm in diameter) occur in clusters along the length of the ganglion. The ganglion appears to be innervated with fibers from the subesophageal and first three abdominal ganglia.The cardiac ganglion is surrounded by a neurilemma and a membranous sheath. The latter is apparently derived from connective tissue cells seen outside the ganglion. Nerve fibers other than those in the neuropil areas are usually surrounded by membrane and cytoplasm of glial cells. Often there are several layers of glial membrane, forming a loose myelin. The cardiac nerves to the heart muscle are also surrounded by a neurilemma, and the axons are surrounded by glia. The motor nerves contain lucent vesicles 60-100 nm and opaque granules 120-180 nm in diameter.In the cardiac ganglion, some nerve cell bodies have complex invaginations of glial processes forming a peripheral trophospongium. In the neuropil areas, nerve cell processes are often in close apposition. The septilaminar configuration typical of gap junctions is common, with gap distances of 1-4 nm. In tissues stained with lanthanum phosphate during fixation, we found gaps with unstained connections (1-2 nm diameter) between nerve-nerve and glial-nerve cell processes. Annular or double-membrane vesicles in various stages of formation were also seen in some nerve fibers in ganglia stained with lanthanum phosphate.Nerve endings with electron-lucent vesicles 40-60 nm in diameter are abundant in the cardiac ganglion, suggesting that these contain the excitatory transmitter of intrinsic neurons of the ganglion. Less abundant are fibers with membrane-limited opaque granules, circular or oblong in shape and as much as 330 nm in their longest dimension. Also seen were some nerve endings with both vesicles and granules.
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  • 152
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    Journal of Morphology 184 (1985), S. 253-261 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The location and arrangement of the pancreatic endocrine tissue in larval and adult Geotria australis (Geotriidae) differ markedly from those exhibited by the comparable stages of Northern Hemisphere lampreys (Petromyzontidae). In larval Geotria australis, the main zones of islet proliferation are located laterally between the oesophagus and the inner edge of the two large intestinal diverticula unique to this species rather than dorsal and ventral to the oesophagus. In adult Geotria australis, the islet follicles are closely packed into a single discrete capsule which could be easily removed surgically, rather than into cranial, intermediate, and caudal cords. The differences in the adult can be related to a lack of involvement of the bile duct in islet formation during metamorphosis. While B cells were found in both larval and adult islet follicles, the PI acidophilic cells and argyrophilic cells, which appeared respectively at stages 3 and 4 in metamorphosis, were present in all adult stages.
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  • 153
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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    Topics: Biology , Medicine
    Notes: The crinoid arm muscles consist of obliquely striated fibers with striking differences in function and in ultrastructural features. These fibers can be distinguished mainly on the basis of different myofilament arrangements (A- and B-type patterns) and are variously combined at different levels (proximal, intermediate, and distal portions) of the arm. Some rare smooth fibers (C-type) are irregularly distributed in the periphery and in the core of the bundle. The characteristic features of the A- and B-type obliquely striated fibers are (1) a continuous and homogeneous structure of the Z line and (2) a very heterogeneous arrangement of myosin filaments which vary widely in size, number, and distribution from section to section. The significance of such an atypical, obliquely striated muscle may be related to the double skeletal system combination (endoskeleton and hydroskeleton) of the crinoid arms.
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  • 154
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    Journal of Morphology 185 (1985), S. 89-100 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Eight secretory cell types are identified in the clitellar epithelium of Eisenia foetida, of which five have been described in detail previously (i.e., the large granular, fine granular, metachromatic, orthochromatic, and small granular proteinacecus cells).The remaining three secretory cell types are mucus-producing cells specific to the clitellar epithelium (type 3), cells associated with the chaetal follicles (type 4), and cells that occur exclusively in the tubercula pubertatis (type 5). Type 3 cells secrete a mucus containing neutral and acid mucosubstances. Ultrastructurally, type 3 cells are characterized by membrane-bound globules 0.4 to 3.7 μm in diameter. The contents of the globules have a finely reticulate appearance. The secretion of type 4 cells contains a collagenlike protein and neutral and sulfated acid mucosubstances. Type 4 cell secretory granules are membrane bound and range in diameter from 0.8 to 1.6 μm. They contain large, electron-dense, spheroid cores which are surrounded by parallel orientated microfibrils 14 nm in diameter. Type 5 cells give variable responses to the histochemical techniques used in the present study. An elastinlike protein is detected in about half of the type 5 cells and acid and neutral mucosubstances in the remainder. At the ultrastructural level the secretory granules vary in shape from spheroid to polygonal. Their finely, electron-dense contents exhibit progressive swelling which results in the eventual rupture of the limiting membranes of the granules. The necks of types 3, 4, and 5 cells contain a peripheral ring of microtubles (20 ± 1 nm in diameter).
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  • 155
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    Journal of Morphology 185 (1985), S. 101-114 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Paraffin sections of an ontogenetic series of embryos of the viviparous lizard Gerrhonotus coeruleus and the oviparous congener G. multicarinatus reveal that although general features of the development of the chorioallantoic and yolk sac membranes are similar, differences are evident in the distribution of the chorioallantoic membrane in late stage embryos. An acellular shell membrane surrounds the egg throughout gestation in both species although the thickness of this structure is much reduced in G. coeruleus over that of G. multicarinatus. The initial vascular membrane to contact the shell membrane in both species is a trilaminar omphalopleure (choriovitelline membrane) composed of ectoderm, mesoderm of the area vasculosa, and endoderm. This transitory membrane is replaced by the vascularized chorioallantois as the allantois expands to contact the inner surface of the chorion. Prior to the establishment of the chorioallantois at the embryonic pole, a membrane begins to form within the yolk ventral to the sinus terminalis. This membrane, which becomes vascularized, extends across the entire width of the abembryonic region and isolates a mass of yolk ventral to the yolk mass proper. The outer membrane of the yolk pole is a nonvascular bilaminar omphalopleure (chorionic ectoderm and yolk endoderm). In G. multicarinatus the bilaminar omphalopleure is supported internally by the vascularized allantoic membrane, whereas in G. coeruleus the allantois does not extend beyond the margin of the isolated yolk mass and the bilaminar omphalopleure is supported by the vascularized intravitelline membrane. Both the chorioallantoic placenta (uterine epithelium, chorionic ectoderm and mesoderm, and allantoic mesoderm and endoderm) and the yolk sac placenta at the abembryonic pole (uterine epithelium, chorionic ectoderm, and yolk sac endoderm) persist to the end of gestation in G. coeruleus.
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  • 156
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    Journal of Morphology 185 (1985), S. 143-143 
    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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  • 157
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    Journal of Morphology 185 (1985), S. 115-129 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An ovarian follicle of Drosophila consists of an oocyte, 15 nurse cells, and hundreds of follicular epithelial cells. A freeze-fracture analysis of the surfaces between glutaraldehyde-fixed ovarian cells showed that all three cell types were interconnected by gap junctions. This is the first report of gap junctions between adjacent nurse cells, between nurse cells and oocytes, and between follicle cells and oocytes in Drosophila. Since we did not observe intramembranous particle clumping into crystalline patterns and since structurally different gap junctions occurred at different times in development and at different cell-cell interfaces, it is unlikely that fixation artifacts influenced particle distribution in our experiments. A computer-assisted morphometric analysis showed that the extent, size, and morphology of gap junctions varied with development and that these junctions can cover up to 9% of the cell surfaces. To test the role of gap junctions in follicular maturation, we studied ovaries from flies homozygous for the female sterile mutation fs(2)A17, in which follicles develop normally until yolk deposition commences. During the development of mutant follicles, gap junctions became abnormal before any other morphological aspect of the follicle. These studies show that gap junctions are available to play an important role in coordinating intercellular activities between all three cell types in ovarian follicles of Drosophila.
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  • 158
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    Journal of Morphology 185 (1985) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 159
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    Journal of Morphology 185 (1985), S. 131-142 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the four-eyed fish, Anableps (Atheriniformes, Anablepidae), eggs are fertilized and embryos develop to term within the ovarian follicles. Development is highly matrotrophic. During gestation, the largest term embryo of A. anableps examined had grown to a total length of 51 mm and attained a dry weight of 149 mg. The postfertilization weight increase is 298,000%. The largest term embryo of A. dowi examined had grown to a total length of 77 mm and attained a dry weight of 910 mg. The postfertilization weight increase is 843,000%. Embryonic weight increases result from nutrient transfer across the follicular placenta. This structure is formed by apposition of the maternal follicular epithelium to absorptive surface cells of the embryo's pericardial trophoderm. The latter, a ventral ramification of the pericardial somatopleure, replaces the yolk sac during early gestation. The external surface of the pericardial trophoderm develops hemispherical projections, termed vascular bulbs. Within each bulb, the vascular plexus of the trophoderm expands to form a blood sinus. Cells of the external surface of the bulbs possess microplicae. Microvilli are absent. During middle to late gestation, the juxtaembryonic follicular epithelium differentiates into two regions. One region consists of shallow, pitlike depressions within which vascular bulbs interdigitate in a “ball and socket” arrangement. Follicular pits are formed by the curvilinear distortion of the apical surfaces of follicle cells. The second region in contact with the dorsal and lateral surfaces of the embryo, is comprised of villous extensions of the hypertrophied follicular epithelium. In both regions, follicle cells appear to constitute a transporting rather than a secretory epithlium. In terms of percentage of weight increase, the follicular placenta of Anableps appears to be the most efficient adaptation for maternal-embryonic nutrient transfer in teleost fishes and closely approaches the efficiency (1.2 × 106%) of oophagy and embryonic cannibalism in lamnoid sharks.
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  • 160
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    Journal of Morphology 185 (1985), S. 155-182 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Regular chewing was studied in the specialized Malagasy insectivore Tenrec ecaudatus with the aid of precisely correlated electromyography of the main adductors, digastrics, and two hyoid muscles and cineradiography for which metallic markers were placed in the mandibles, tongue, and hyoid bone. During the power stroke the body of the mandible moves dorsally and medially. The medially directed component of movement at this time is greatly increased by simultaneous rotation of the mandible about its longitudinal axis. The highly mobile symphysis, spherical dentary condyle, loss of superficial masseter muscle and zygoma, and the simplified zalamnodont molars all appear to be related to the large amount of mandibular rotation that occurs during occlusion. The balancing side lateral pterygoid muscle (inferior head) apparently shifts the working side mandible laterally during the last part of opening and the first part of closing. The working side temporalis and the superficial masseter muscle are both responsible for the shift back to the midline. The temporalis is usually active to the same extent on the working and balancing sides during the power stroke. The level of activity (amplitude) of the temporalis and duration of the power stroke increase with harder foods. Whenever soft foods are chewed, the superficial masseter is only active on the working side; whenever foods of increasing hardness are chewed, its level of activity on the balancing side increases to approach that of the working side. Mandibular rotation is greatly reduced when hard foods are chewed.
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  • 161
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    Journal of Morphology 185 (1985), S. 183-193 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Total dissection of a randomly collected sample of 202 adult and subadult eutherian mammals, combined with site-specific adipocyte volume determination, shows that the number of adipocytes in the body is proportional to (Body Mass)0.74 for predominantly carnivorous species and to (Body Mass)0.78 for mainly herbivorous, nonruminant mammals. Adipocyte expansion or shrinkage, not proliferation or depletion of adipocyte number, is the principal mechanism of adipose tissue enlargement and reduction. Therefore, the adipocytes of large mammals are larger than those of smaller specimens of similar dietary habits and fatness. We suggest that the presence of more numerous, smaller adipocytes in smaller mammals is related to their higher mass-specific metabolic rate. The adipose tissue of mammals with a predominantly carnivorous diet contains 4.6 times as many adipocytes as that of herbivorous nonruminants of similar body mass; but nonruminant herbivores are not necessarily fatter because the adipocytes of carnivorous mammals are proportionately smaller than those of nonruminant herbivores. We suggest that a carbohydrate-based energy metabolism is associated with fewer, relatively larger adipocytes and that when lipids and proteins form the major dietary energy source, adipose tissue consists of a greater number of smaller adipocytes.
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  • 162
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    Journal of Morphology 185 (1985), S. 195-202 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In a randomly collected sample of 91 wild and captive birds, in which there is no significant correlation between fatness and body mass, the total number of adipocytes is proportional to (Body Mass)0.68. The adipose tissue of larger birds consists of proportionately fewer adipocytes; therefore, the adipocytes of larger birds are larger, in relation to the fatness of the specimens, than those of the smaller species. The cellularity of the adipose tissue of predominantly carnivorous birds does not differ from that of mainly herbivorous species. The adipocytes in the abdominal cavity and around the thigh are on average 29% larger than those in the superficial and clavicular depots; however, these site-specific differences were variable and were statistically insignificant in many of the specimens. The size of the adipocyte complement is highly variable even among specimens of a single species and similar body mass, suggesting that in birds the number as well as the volume of adipocytes might increase or decrease as the adipose tissue expands or shrinks.
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  • 163
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    Journal of Morphology 185 (1985), S. 145-154 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The composition of myofiber types varies within thigh muscles of chickens. The present study was designed to determine whether or not myofiber types were distributed uniformly across the diameter of the thigh muscles of chickens. Cross sections from middle portions of muscles were used histochemically to examine differences in distribution and composition of myofiber types in the muscles. Myofibers that reacted moderately (M) or strongly (S) for myosin adenosine triphosphatase (ATPase) after preincubation at pH 4.3 were classified as type I. Type I myofibers reacted weakly (W), moderately (M), or strongly (S) for ATPase after preincubation at pH 10.6; these type I myofibers were subclassified into four types (ISW, ISM, ISS, and IMM). Myofibers that reacted negatively for acid-stable ATPase and strongly for alkali-stable ATPase were classified into two types: type IIA, with strong NADH tetrazolium reductase (NADH-TR), and type IIB, with weak NADH-TR activity. The M. pubo-ischio-femoralis pars lateralis had numerous type IIA myofibers and very few type ISM myofibers, whereas the pars medialis had many type IMM myofibers and few type ISS and IIA myofibers. The type I group of myofibers did not exceed about 50% in the other muscles, which had one to three types of type ISW, ISM, and ISS myofibers. The Mm. femorotibiales had more type ISW, and ISM myofibers in the deep regions near the femur than in the superficial regions. The M. iliotibialis cranialis, M. iliofibularis, and M. flexor cruris medialis had more type ISW, ISM, or ISS myofibers in the medial regions than in the lateral regions. A few type ISW myofibers were scattered in the cranial part of M. iliotibialis and in the M. ambiens. The M. flexor cruris lateralis pars pelvica had type IIA and IIB myofibers exclusively. All the muscles had type IIA myofibers. Type IIB myofibers existed in the muscles except the M. puboischio-femoralis. Type IIA and IIB myofibers differed in proportion in different muscles and in their different regions. The type I group of myofibers was generally concentrated more in the deep regions near the femur and in the medial regions than in the superficial and lateral regions of the thigh muscles. The distribution of type IIA myofibers resembled that of type I group. Type IIB myofibers showed a distribution opposite to that of type I group and IIA myofibers. The spatial distribution of myofiber types within individual muscles can account for the various locomotory and postural requirements of the thigh.
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  • 164
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    Journal of Morphology 185 (1985), S. 217-222 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the Mexican axolotl (Ambystoma mexicanum), the pronephros begins to form at the four-somite stage. It is initially continuous with the posterior-lateral region of somite 2 and the lateral margin of somites 3 and 4. By the seven-somite stage, the pronephros has become compacted, and the cells are now morphologically distinct from the somitic cells. At this stage, a mass of loosely connected cells, apparently originating from the lateral mesoderm, is seen below somites 4 and 5. By the eight-somite stage, these presumptive duct cells have migrated dorsally to the duct path and are found below somites 5-7. By the nine-somite stage they have begun to migrate caudally.
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  • 165
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    Journal of Morphology 186 (1985), S. 369-377 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Light and electron microscopic observations of the lateral-line organs of larval Ichthyophis kohtaoensis confirmed earlier reports of the occurrence of two different types of lateral-line organs. One type, the ampullary organ, possesses 15-26 egg-shaped sensory cells. Each sensory cell extends a single kinocilium surrounded by a few microvilli into the ampullary lumen. This is in contrast to the ampullary organs of urodele amphibians that contain only microvilli. The second type of organ, the ordinary neuromast, has 15-24 pear-shaped sensory cells arranged in two to three rows. Each sensory cell shows a kinocilium that is asymmetrically placed with respect to both a basal plate and approximately 60 stereovilli. The sensory cells of ampullary organs are always separated by supporting cells; those of neuromasts are occasionally in contact with one another. Numerous (neuromasts) or few (ampullary organs) mantle cells separate the organs from the epidermal cells. Only afferent synapses are found in the ampullary organs whereas vesicle-filled fibers together with afferent nerve terminals are found in neuromasts. Both organs contain similarly sized presynaptic spheres adjacent to the afferent fibers. It is suggested that the neuromasts have a mechanoreceptive function, whereas the ampullary organs have an electroreceptive one.
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  • 166
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    Journal of Morphology 183 (1985) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 167
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    Journal of Morphology 183 (1985), S. 15-23 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: At least five nonporous sensilla with inflexible sockets (npsensilla) occur on each antenna of both sexes of adult Rhodnius prolixus. Externally the sensillum appears as a short, rounded peg set into a pit surrounded by a depression. A very electron-dense material occurs in the peg lumen and the inner aspect of the pit. Filamentous extensions of this material radiate into the overlying outlets.Each sensillum is innervated by three neurons with unbranched dendrites. Two dendrites extend to the peg tip and distally are covered by a dendritic sheath. The portion of these dendrites within the sheath contains a large number of microtubules. The third dendrite terminates near the base of the dentritic sheath and partially wraps around the other two dendrites. Three sheath cells are associated with each sensillum.Based on similarities in structure with sensilla of known function it is probable that the np-sensilla of R. prolixus are thermo-/hygrosensilla responding to cold, dryness and wetness. The sensilla have a number of structural similarities with insect rectal sheath cells known to absorb atmospheric water by electroosmosis. Possibly this process leads to volumetric alterations of cuticular elements associated with the dendrites and ultimately to mechanotransduction.
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  • 168
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    Journal of Morphology 183 (1985), S. 1-13 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The structures and distribution of encapsulated muscle receptors were examined in serial transverse sections of flexor carpi radialis in the adult cat. Four types of receptors (muscle spindles, Golgi tendon organs, paciniform, and Pacinian corpuscles) were identified. Their structures resembled those encountered in other limb muscles. Pacinian corpuscles were rare and occurred only in the external fascial coat of the muscle near its origin. The other three receptor types were distributed in an uneven but consistent pattern throughout the muscle. As noted previously (Gonyea and Ericson, '77), spindles were largely confined to a deep muscle region comprising less than 20% of the muscle volume, located directly between the long tendon of origin and the tendon of insertion. This region contains the largest proportion of type SO muscle fibers (Gonyea and Ericson, '77). Tendon organs and paciniform corpuscles were concentrated along the tendons that lined the spindle-rich muscle region. This region appeared to be composed of extrafusal fibers that were shorter and of more oblique pinnation than those in other regions. The localization of muscle receptors to the “oxidativex” core of the muscle in its direct line of pull may have functional implications for afferent input to the spinal cord which are discussed. In addition, the possibility is raised that there are more paciniform corpuscles in flexor carpi radialis (and possibly other muscles) than previously thought.
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  • 169
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    Journal of Morphology 183 (1985), S. 25-50 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The tree sloths, Bradypus and Choloepus, show unusual masticatory specializations, compared to each other and to other mammals. Both have an incomplete zygomatic arch with descending jugal process, a complex superficial masseter, a large temporalis and medial pterygoid musculature, and a lateral pterygoid with two heads. In Choloepus the deep masseter and zygomaticomandibularis are typical when compared to other mammals. However, in Bradypus there is an ascending jugal process from which enlarged and vertically oriented deep masseter and zygomaticomandibularis muscles originate. Although both sloths are folivores, the anterior teeth in Choloepus are caniniform, while those of Bradypus have lost such elongation. In both sloths the glenoid cavity is similarly located; however, in Bradypus the cranioman-dibular joint is raised above the occlusal plane, and the pterygoid flanges are elongated.Prediction of the evolutionary sequence of cranial changes from Choloepus- like (primitive) to Bradypus- like (derived) morphology is based upon the most parsimonious model of masseter-medial pterygoid complex changes for masticatory efficiency improvement. The model proposes that the condylar neck in Bradypus was elongated and that this single change predicated a series of other structural changes.Mandibular movement patterns in both sloths showed anteromedially directed unilateral power strokes as in other mammals. Puncture-crushing, tooth-sharpening, and chewing cycles are distinct in Choloepus, less so in Bradypus. The masticatory rate is slow in sloths compared to other mammals of similar body size, averaging 590 ms per cycle for Choloepus and 510 ms for Bradypus.
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  • 170
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    Journal of Morphology 183 (1985), S. 51-85 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The objectives of this research were to investigate the morphology of the head skeleton and muscles of the female mosquito, Culiseta inornata (Williston). The skeletal parts were examined after maceration in KOH. The attachments of muscles were determined by dissection. Observations were made with the aid of a dissecting microscope at 70× and lower. Each skeletal part and muscle is illustrated and described. Conclusions regarding the skeleton are as follows: (1) the clypeal area is composed of an anteclypeus and postclypeus, (2) the suture between the anteclypeus and postclypeus is rigid and cannot function as a hinge, (3) the dorsal wall of the labrum terminates at its union with the anteclypeus, (4) the dorsal and epipharyngeal walls of the labrum are united apically, (5) the gena and postclypeus are not separated by a suture, and (6) the labellum is composed of three segments and the furca, of some authors, is absent. Twenty-five muscles were identified, and the origin, insertion, and action of each is described. The tormo-epipharyngalis muscle is attached anterior to the cibarium and fulcral plates. Its origin is on the clypeal apodeme and the insertion is on the epipharynx. This result confirms earlier reports and disagrees with some recent authors. The maxillary teeth are not designed to draw the fascicle into the tissues, but the cervical and leg muscles accomplish the probing process during feeding on a host. An undescribed muscle of the mandible is reported.
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  • 171
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    Journal of Morphology 183 (1985), S. 145-153 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The differentiation of fiber type characteristics in the anterior (ALD) and posterior (PLD) latissimus dorsi muscles is examined by the freezefracture technique in 1-, 7- and 30-day-old chicks. Several characteristics of plasma membrane (caveolae, rectilinear arrays, intramembranous particles) and sarcoplasmic reticulum which show fiber type differences in the adult ALD and PLD muscles are compared in the developmental stages. The caveolar density in the ALD fibers is about 20/μm2 at 1 day increasing to about 37/μm2 at 30 days, whereas in the PLD fibers it remains at about 20/μm2 during this period. The distribution of the caveolae in the two muscles is different from the begining; in the ALD fibers the caveolae are distributed throughout the plasma membrane and in PLD fibers they are patterned into clusters overlying the I band regions. The density of intramembranous particles of 1-day ALD and PLD plasma membranes appears similar, but by 7 days the particle counts in the sarcolemma of the ALD muscle are about twice as numerous as those in the PLD muscle. The rectilinear arrays are virtually absent in the ALD muscle, whereas in the PLD muscle their density is about 10/μm2 at 1 day and about 20/μm2 at 7 days. Already at 1 day posthatching the SR in ALD and PLD fibers has the adult configuration, i.e., an open irregular network in ALD fibers and periodically arranged tubules with triadic expansions in the PLD fibers. It is concluded that the membrane structure of ALD and PLD muscles is already different at hatching, and at 1 week the differences are identical to those of slow and fast fibers of the adult stage. The membrane changes, therefore, do not support the view that the ALD muscle undergoes a transitional, fast-type stage in posthatching chicks.
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  • 172
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    Journal of Morphology 183 (1985), S. 165-176 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Cytodifferentiation and hard tissue formation were studied in Anolis to collect information regarding the phylogenetic history of enamel and the functional significance of the events seen in the mammalian tooth during differentiation. The differentiation of the ameloblasts of Anolis, like that of mammals, shows two phases: In the early phase, the cells are short and rich in free ribosomes, in the late phase the cells elongate, develop an extensive rough endoplasmic reticulum, and the Golgi apparatus moves into that part of the cell next to the basal lamina (the cell apex). The early epithelial-mesenchymal interface resembles that of mammals, suggesting that early mechanisms of induction and epithelial-mesenchymal interaction are similar in Anolis and in mammals.Preameloblast processes and preameloblast-preodontoblast contacts in Anolis are rudimentary compared to those of mammals. While in mammals the preameloblast processes shape the future DEJ (dentin-enamel junction), their involvement in establishing the shape of the DEJ of Anolis is questionable. We suggest that the great development of preameloblast-preodontoblast contacts in mammals may simply increase the efficiency of inductive interactions between these cell types.
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  • 173
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    Journal of Morphology 183 (1985), S. 177-183 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The spermatozoa of Rhinolophus capensis are stored in the cauda epididymidis for about 10 months, 4 months prior to copulation and 6 months after copulation. Electron microscopy has shown the occurrence of sperm defects (mitochondrial proliferation, bending and coiling of the tail, and Dag defect) throughout the period of sperm storage. However, these defects are more common during the postcopulation period, when excess spermatozoa are being removed, suggesting that they may be associated with sperm degradation.
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  • 174
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    Journal of Morphology 186 (1985) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 175
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Scanning electron microscopy of six stages of Lytechinus variegatus embryos from hatching through gastrulation reveals changes in the shapes of the ectodermal cells and morphological changes in the extracellular material (ECM) in relation to the locations and migratory activities of mesenchyme cells. The classical optical patterns in the blastular wall (Okazaki patterns) are due to differential orientations of the cells, which bend and extend sheet-like lamellipodia over adjoining cells toward the eventual location of the primary mesenchymal ring. The blastocoelic surfaces of the blastomeres become covered with a thin basal lamina (BL) composed of fibers and nonfibrous material. During primary mesenchyme cell (PMC) ingression, a web-like ECM is located in the blastocoel overlying the amassed PMCs. This ECM becomes sparse in migratory mesenchyme blastulae, and is confined to the animal hemisphere. Localized regions of intertwining basal cell processes in the blastular wall are also present during PMC migration. While a distinct BL is present during early and midgastrulation, blastocoelic ECM is absent. Late gastrulae, on the other hand, have an abundance of blastocoelic ECM concentrated near secondary mesenchyme cell protrusive activity. ECM appearing at both the early mesenchyme and late gastrula stages are probably remnants of degraded BL and intercellular matrix preserved by fixation for SEM. Thus, early mesenchyme ECM is formed of BL material whose degradation is necessary for entry of PMCs into the blastocoel. Late gastrula ECM is apparently a degradation product of BL and intercellular material whose destruction is required for fusion of the gut with oral ectoderm in formation of the mouth.
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  • 176
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The teeth of the adult plethodontid salamander, Plethodon cinereus, were examined by light and electron microscopy with emphasis on the ringlike zone of uncalcified dentin that divides the calcified portion of each tooth into a proximal pedestal and a distal apex. The uncalcified region displays radial asymmetry, forming an integral part of the posterior wall of the tooth but bulging into the pulp cavity anteriorly, thus forming a hingelike structure. All portions of the dentin, including the uncalcified region, are composed predominantly of collagenous fibers but lack elastin. In scanning electron micrographs of teeth from which the oral mucosa has been removed, the location of the anterior uncalcified hinge is marked externally by a notch-like articulation of the apex and pedestal. Sites of transition between calcified and uncalcified areas of the dentin show no special modifications in transmission electron micrographs, but collagenous fibers in calcified portions are associated with more electron-dense amorphous material than are those in the uncalcified region. Odontoblasts associated with the uncalcified region possess ultrastructural features closely resembling those of odontoblasts found in calcified areas. The uncalcified region seems to afford the teeth a certain degree of flexibility, and the asymmetry of the region appears to allow the teeth to flex only in a posterior direction, thus facilitating the entry of living prey but hindering its escape. The uncalcified region also seems to permit the apex of a tooth to break away from its pedestal without damage to underlying bone.
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  • 177
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    Journal of Morphology 186 (1985), S. 31-44 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The paired salivary glands of unfed adult Haemaphysalis (Rhipistoma) leachi contain one type of agranular and three types of granular alveoli connected to a salivary duct system. Type I agranular alveoli consist of one large, central cell surrounded by peripheral cells with numerous basal membrane infoldings indicative of epithelia involved in fluid transport. Glycogen particles, lipid-like droplets, and the parallel pattern of infolded membranes disappeared from the peripheral cells during feeding. Types II, III, and IV granular alveoli contain some agranular interstitial epithelial cells, cap cells, and fundus cells, but are predominantly composed of structurally different granular cell types a, b, c, d, e, and f. Agranular cells develop during the early stages of feeding. Granular a, c, e, and f cells release their granules directly after attachment to the host and possibly are involved in cement secretion required for firm attachment to it. The b cell granules are replaced by b1 filamentous granules during feeding. Golgi bodies and rough endoplasmic reticulum (RER) participate in the formation of most types of granules. The d cells contain lamella-like structures and condensing vacuoles, probably responsible for lysosome formation. The main salivary duct and all types of alveoli are innervated by neurosecretory axons.
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  • 178
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    Journal of Morphology 183 (1985), S. 129-129 
    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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  • 179
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Muscle architecture, moment arms, and locomotor movements in the distal limb segments of the procyonids Nasua (coati) and Procyon (raccoon) are analyzed with reference to patterns of muscle fiber length. This study addresses the hypothesis that relative fiber lengths among muscles in a muscle group can be predicted on the basis of correlates of muscle tension. The results include the following: (1) consistent patterns of fiber length of muscles in a muscle group exist within and between the two genera. (2) Differences in fiber length between muscles can be accounted for by two principal correlates of muscle excursion - length of a muscle's moment arm about a joint and jointangle excursion. (3) Muscle fiber pinnation permits increased tendon excursion, but this effect is relatively small in comparison to the effects of moment-arm length and joint-angle excursion. (4) Corollary action between two or more joints (or lack thereof) is an important factor in determination of fiber lengths.
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  • 180
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    Journal of Morphology 183 (1985) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 181
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Germanium (Ge), in the form of germanic acid, at a Ge/Si molar ratio of 1.0 inhibits gemmule development and silica deposition in the marine demosponge Suberites domuncula. Lower Ge/Si ratios inhibit the growth in length of the silica spicules (tylostyles) producing short structures, but with relatively normal morphology and close to normal width; spherical protuberances occasionally occur on these spicules. A few of the short spicules possess completely round rather than pointed tips. Many of the latter develop when Ge is added (pulsed) to growing animals, thus inducing a change in spicule type. These results indicate that the growth in length of the axial filament is more sensitive to Ge inhibition than is silica deposition and that pointed spicule tips normally develop because the growth of the axial filament at the spicule tip is more rapid than silica deposition. Newly formed spicules initiate silica deposition at the spicule head but the absence of Ge-induced bulbs as in freshwater spicules (oxeas) leaves open the question of whether there is a silicification center(s) present in Suberites tylostyles. The morphogenesis of freshwater oxeas and of marine tyolstyles appears fundamentally different-bidirectional growth in the former and unidirectional growth in the latter. X-ray analysis demonstrate relatively uniform Ge incorporation into the silica spicules with considerable variation from spicule to spicule in the incorporated level. Increased silicic acid concentration induces the formation of siliceous spheres, suggesting that the axial filament becomes prematurely encased in silica.
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  • 182
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    Journal of Morphology 183 (1985), S. 137-144 
    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 investigates the morphological aspects of nonself recognition between three incrusting sponge species living in contact.Two types of association have been observed: nonmerging fronts and epizoism. In two of the three combinations studied, Hymeniacidon sanguinea/Halichondria panicea and Halichondria panicea/Ophlitaspongia seriata, nonself contacts consisted of either epizoism or of nonmerging fronts. In contrast, only nonmerging fronts were observed between Hymeniacidon sanguinea and Ophlitaspongia seriata.In the two types of associations, the main phenomenon consists of the isolation of the foreign sponges by a spongin barrier secreted by the partners in the zone of contact. The microscpic structure and the thickness of the barrier vary according to the type of association and the species paired, but they are clearly defined for a given combination.The conditions required for the establishment of epizoism and the existence of a natural xenogeneic tolerance between sponges are discussed.
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  • 183
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Immunocytochemical investigation of the eyestalks of the larval and postlarval stages of the crayfish Astacus letodactylus, using an anti-Astacus-CHH serum, shows that immunopositive staining starts in the immediate posthatching larval stage, in neurosecretory cells of the medulla terminalis ganglionic X-organ (MTGX), in an MTGX-sinus gland tract, and in part of the axon terminals of the sinus gland. The number of these immunopositive cells increases during postlarval development. Neurosecretory granules belonging to distinct axon terminals of the neurohemal region show immunostaining. The mean diameter of the stained granules increases during postlarval development. The hemolymph glucose concentration in adult crayfish increases after injection of larval eyestalks.
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  • 184
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the development of the horseshoe crab, Limulus polyphemus, the fertilized egg undergoes a complicated cleavage (Stages 1-3) resulting in blastoderm formation (Stage 4). Stage 1 involves intralecithal cleavage and consists of nine discrete surface modifications (events) which have been briefly described with light microscopy by Brown and Barnum ('83). Since in Stage 1 the cortical reaction (events 1-4) has already been examined with ultrastructural methods, the objectives of the present study were to examine with scanning electron microscopy: (1) the first two of three intermittent granulations (events 5 and 7), and (2) the associated events characterized by smooth surfaces (events 4, 6, and 8). The first granulation occurs 2 1/2 to 3 hours after fertilization (22°C) and lasts approximately 1 1/2 hours. The second granulation appears approximately 5 hours after fertilization and lasts about 3 hours.The dynamic changes that occur during the two granulations involve the transformation of a smooth appearing embryonic surface, liberally coated with microvilli, into a granule-dominated surface on which microvilli are greatly reduced in number. Also of considerable interest are the numerous projections which begin to appear on the surface near the end of the second granulation (event 7) and dominate the surface of the following smooth step stage (event 8). Hypotheses on the significance of these dynamic changes and surface modifications involve relationships to the cell cycle, possible mechanisms for membrane storage, and secretory function.
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  • 185
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    Journal of Morphology 183 (1985), S. 219-224 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ultrastructural study of previtellogenic oocytes found in cystlike clusters scattered throughout the length of the bilobed ovary of the hermit crab Coenobita clypeatus shows a high nuclear:cytoplasm ratio. Large, round nuclei containing synaptinemal complexes serve as good temporal markers for identification of previtellogenic oocytes. The cytoplasm contains many smooth-membraned vesicles filled with granules and probably of nuclear origin. In addition to its complement of Golgi complexes, endoplasmic reticulum, mitochondria, and free ribosomes, the cytoplasm also contains stacks of annulate lamellae, a feature not previously described for decapod oocytes. Typically, the previtellogenic oocyte with its accumulation of ribosomes has the appearance of a nonsynthetic cell preparing to go through a metabolic transition.
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  • 186
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    Journal of Morphology 183 (1985), S. 199-217 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The major cranial vibrissae in the golden hamster can be moved in complex ways that suggest they are served by a finely controlled motor system. Movements are hypothesized to be the products of (1) differential blood flow and pressure regulation in the sinus surrounding each vibrissal follicle, (2) contractions of the striated facial muscles, and (3) elastic rebound in the connective tissues. The vasculature contributes hydrostatic forces that (a) erect the vibrissae slightly and distort their connective tissue bedding, (b) rigidify the vibrissal capsules, thus forming firm bases of attachment for certain facial muscles, and (c) theoretically provide a pressure plate around the follicle, important in lowering the firing thresholds of receptor endings. The facial muscles supply the major forces in erection and protraction of the vibrissae by acting on both the capsules and the connective tissue bedding. The connective tissues are organized into capsular and extracapsular systems that serve to stabilize the vibrissae and return them to initial rest positions.The slight movements of the genal vibrissa are the effects of vascular and connective tissue dynamics, the musculature being uninvolved. Wide angle movements of the supraorbital vibrissae are products of the vasculature and connective tissues, plus contractions of the Mm. orbicularis oculi and frontalis. Mystacial vibrissal movement is quite complex. The vasculature supplies a small degree of capsular erection and mystacial pad distortion, but primarily rigidifies the capsules. The bulk of erection and protraction is produced by the M. nasolabialis profundus (NLP) and the vibrissal capsular muscles (VCM). The NLP distorts the mystacial pad; the VCM tilt the capsules relative to the pad. Retraction is mainly accomplished by elastic rebound in the pad, this being aided in its extreme degrees by the Mm. nasolabialis and maxillolabialis. The Mm. nasolabialis superficialis and buccinator pars orbicularis oris help to spread the vibrissae into a dorsoventral fan and stabilize the mystacial pad during whisking.
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  • 187
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    Journal of Morphology 183 (1985), S. 311-326 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: External features of the egg, developing embryo, and first instar nymph of Kamimuria tibialis are described. The embryonic development from the germ disc to the full-grown embryo is divided into 12 stages. The saclike embryonic rudiment is formed by the bending and folding of the germ disc. The embryo first elongates at the egg surface and then sinks into the yolk due to caudal flexure. In the head, four paired protocerebral lobes differentiate and the fourth lobes are thought to be the rudiments of preantennal ganglia. The columnar serosal cells appear at the posterior pole of the egg and they disappear before katatrepsis. The coniform chloride cells occur at the hind margins of the first nine abdominal segments in the full-grown embryo and first instar nymph. Amnion formation in K. tibialis is very similar to that of Allonarcys proteus and the Isoptera. It is proposed that the immersed type of growth pattern of embryos is divided into two subtypes in hemimetabolous insects; one is in the Palaeoptera and Paraneoptera, and the other is in the Plecoptera, Orthoptera, Notoptera, Isoptera, Embioptera, and the blattarian, Periplaneta americana.
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  • 188
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study was designed to investigate and determine for how long, after either hypophysectomy or the third (last) growth hormone injection (to previously hypophysectomized newts), the circulating and now declining titers of endogenous or exogenous hormone remained at a sufficient concentration to permit a morphologically normal forelimb regeneration response in the adult newt Notophthalmus viridescens.To examine the declining levels of endogenous hormone (hormone withdrawal series [HW]), left forelimbs were amputated at specific times following hypophysectomy. Right forelimbs were amputated 5 days prior to hypophysectomy. The declining levels of exogenous hormone hormone replacement series [HR] were examined in newts whose left forelimbs were amputated at specific times following the last of three consecutive alternate-day growth hormone injections that were initiated 5 days post hypophysectomy. Right forelimbs were amputated immediately following the first hormone injection. All experimental animals were sacrificed when their right forelimbs regenerated to an advanced digitiform regenerate. In both series right forelimbs regenerated normally.In the HW series normal regeneration resulted only when forelimbs were amputated within 48 hours post hypophysectomy, whereas in the HR series normal regeneration occurred in only those newts whose forelimbs were amputated within 12 hours of the last hormone injection. The regeneration response of left forelimbs in both series gradually declined with the time interval between either hypophysectomy or hormone injection and forelimb amputation. As the hormone titer declined, fewer limbs initiated a normal response; they became progressively more hypomorphic and eventually failed to undergo typical regeneration.
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  • 189
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    Journal of Morphology 184 (1985), S. 263-276 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the ovarian follicle, the micropylar cell (MPC) is distinguished from neighboring granulosa cells by its larger cell size and its thick cytoplasmic process. The micropylar cell body fits into a shallow depression (micropylar vestibule) on the outer surface of the egg envelope; its process extends through the micropylar canal, which extends from the bottom of the vestibule through the full thickness of the zona pellucida interna. At its distal end, the cell process expands into a bulb which fits into an indentation of the ooplasmic surface immediately beneath the inner opening of the micropylar canal. Intermediate and desmosomelike junctions establish an intimate association between MPC process and oocyte. Various kinds of organelles and inclusions in the MPC show a characteristic pattern of cytoplasmic distribution; rough endoplasmic reticulum with markedly dilated cisternae is found exclusively in the main cell body, while microtubules and thin filaments are observed in the cytoplasmic process.Immediately before or during the breakdown of the germinal vesicle in the intrafollicular oocyte, the cytoplasmic process of the MPC gradually decreases in length and begins to withdraw from the micropylar canal. At the same time, the ooplasmic surface protrudes outward to form a papilla in the canal. The intimate MPC-oocyte association disappears during formation of the ooplasmic papilla. Hydration of the oocyte apparently occurs at the final stage of maturation and probably participates in papilla formation. Although the MPC undergoes degenerative changes as ovulation draws near, it remains attached to the inner surface of the granulosa cell layer even after its association with the oocyte has completely disappeared.We speculate that the micropyle develops during fish oogenesis through the combined activity of the MPC and neighboring granulosa cells. It appears that the cell body of the micropylar cell and nearby granulosa cells exert mechanical pressure on the external surface of the growing oocyte and thus participate in formation of the micropylar vestibule. The cytoplasmic process of the MPC evidently forms a passive barrier to deposition of material for the egg envelope in the animal pole, thereby resulting in formation of the micropylar canal.
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  • 190
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    Journal of Morphology 184 (1985), S. 277-292 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Embryos of goodeid fishes develop to term within the ovarian lumen, where they undergo considerable increase in weight due to transfer of maternal nutrients across a trophotaenial placenta. The placenta consists of an embryonic component, the trophotaeniae, and a maternal component, the ovarian lining. The latter was examined by transmission electron microscopy, scanning electron microscopy, and light microscopy in both gravid and non-gravid ovaries of the viviparous goodeid fish, Ameca splendens. The single median ovary of A. splendens is a hollow structure whose lumen is divided into lateral chambers by a highly folded longitudinal ovarian septum. Germinal tissue occurs within folds of the ovarian lining that extend into each of the two lateral chambers. Matrotrophic embryonic development takes place within ovarian chambers. During gestation, the lining of the ovarian lumen is in direct apposition to body surfaces and trophotaenial epithelia of developing embryos. The ovarian lining consists of a simple cuboidal epithelium, termed the internal ovarian epithelium (IOE), overlying a well-vascularized bed of connective tissue. Cells of the IOE are apically convex. Well-developed granular and agranular endoplasmic reticula and numerous large membrane-bound vesicles with electron-dense content occupy the apical cytoplasm of IOE cells. Two functional states of the same cell type are distinguished within the IOE. Phase I cells contain few, if any, large apically situated vesicles; Phase II cells contain many. Secretory products of the IOE are presumed to be an important source of nutrients for embryonic development. Structural and functional relationships of the IOE to the trophotaenial epithelium of developing embryos are discussed in relation to maternal-embryonic nutrient transfer processes.
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  • 191
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    Journal of Morphology 184 (1985), S. 311-321 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The digestive gland (midgut gland, hepatopancreas) of the American lobster, Homarus americanus (Decapoda: Nephropidae), has one continuous network of connective tissue in which the tubules are embedded and suspended and which forms the limiting layer of the organ. Light- and electron-microscopical observations show that the outer connective-tissue layer investing the entire digestive gland is a typical, fibrous connective tissue, containing hemal sinuses and a variety of cell types embedded in a collagenous matrix. This outer layer is continuous with the connective tissue among the tubules, which lacks a substantial fibrous matrix and lies peripheral to the digestive epithelium of each tubule. It consists of a complex, two-layered, epithelial basement membrane, an area containing cells, a tunica propria, and hemal sinuses. Several types of cells are present between the basement membrane and the tunica propria: contractile cells form a network of circular and longitudinal processes around each tubule, and several types of granulocytes are found in areas where tubules abut.The previously applied terms “myoepithelium” and “myoendothelium” are inappropriate to describe the tissue among the tubules. Instead, the extraepithelial elements are interpreted as forming an extensive connective tissue supporting the functional units of the digestive gland.
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  • 192
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    Journal of Morphology 184 (1985), S. 293-309 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Embryos of the viviparous goodeid fish Ameca spendens develop within the ovarian lumen, where they establish a placental association with the maternal organism and undergo a 15,000% increase in embryonic dry weight. The placenta consists of an embryonic component, the trophotaeniae, and a maternal component, the internal ovarian epithelium. Examination with light microscopy and with transmission and scanning electron microscopy reveals that trophotaeniae of A. splendens are extraembryonic membranes consisting of five ribbon-like processes originating from a tube-like mass of tissue that extends outward from the perianal region of developing embryos. There are two sets of lateral processes and a longer single median process. Trophotaeniae possess an outer epithelium that surrounds a highly vascularized core of loose connective tissue. Epithelial cells possess apical microvilli and a pronounced endocytotic apparatus. Cells of the trophotaenial epithelium are either tightly apposed along their lateral margins or separated by enlarged intercellular spaces. Regions of the trophotaenial epithelium possessing enlarged intercellular spaces are distributed in patches. The trophotaenial epithelium is continuous with the embryonic hindgut epithelium and is considered to be derived from it. Comparison of trophotaenial morphology in A. splendens with that reported in Xenotoca eiseni reveals differences in histological organization. The former possess unsheathed trophotaeniae, whereas the latter are sheathed. We postulate that the apposition of trophotaenial epithelium to the internal ovarian epithelium constitutes a placental association equivalent to a noninvasive, epithelioform of an inverted yolk sac placenta. Structural relationships of embryonic and maternal tissues of the trophotaenial placenta are discussed in relation to maternal-embryonic nutrient transfer processes.
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  • 193
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    Journal of Morphology 184 (1985), S. 323-341 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ultrastructural and light microscopic observations on the organization of thick and thin regions of hydra's tentacles, made on serial sections and on whole fixed, plastic-embedded tentacles, reveal the existence of two levels of anatomical order in the tentacle ectoderm: (1) The battery-cell complex (BCC), composed of a single epitheliomuscular cell (EMC) and its content of enclosed nematocytes and neurons; and (2) the battery cell complex ring (BCC ring), an arrangement of 4 or more BCCs into larger units organized as rings around the circumference of the tentacle. All EMCs of the distal tentacle appear to contain batteries of nematocytes, and are, therefore, called “battery cells.” Apart from battery cell complexes and migrating nematocytes, there are no other cell types in the tentacle ectoderm. Battery cells are composed of three distinct regions: the cell body, peripheral attenuated extensions and myonemes. Thick tentacle bands are composed of cell bodies, whereas thin bands are made up of attenuated extensions. Myonemes contribute to both thick and thin regions. It was confirmed that each battery cell has several myonemes, which appear to interdigitate with myonemes of other more proximal and distal battery cells, but not with battery cells of the same BCC ring. Nematocytes have several basal processes. Some processes insert between myonemes and contact the mesoglea; other processes insert into cuplike extensions of myonemes, and are connected to myonemal cups by desmosomal junctions. These observations are discussed in relation to mechanical and electrical aspects of tentacular contraction and bending.
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  • 194
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    Journal of Morphology 184 (1985), S. 343-350 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: To characterize and classify erythrocytes of ranid tadpoles, alcohol-fixed blood smears were studied with dark field illumination. All preclimax stage (limb bud-foot) Rana castesbeiana tadpoles from ponds in Massachusetts had red blood cells that were polymorphic. The majority of cells (88%) showed a bright, granular luminescence varying from white to blue-grey, whereas, cytoplasm of the other cells was smooth, black, and nonluminescent. On the other hand, tadpoles in similar stages from other species (Rana clamitans, Mass. and Rana pipens, Vermont) and from R. catesbeiana tadpoles from other locations (Wisconsin and North Carolina) had no observable cytoplasmic luminescence in any of their red blood cells. Moreover, as Mass. R. catesbeiana underwent metamorphic climax their luminescent cells disappeared and were replaced by small, round, dark, nonluminescent cells, precursors of the oval, nonluminescent erythrocytes characteristic of adult frogs. Cells with black nonluminescent cytoplasm generally contained nuclei which were luminescent. In conclusion, two main types of red blood cells-those with and those without cytoplasmic luminescence-are distinguishable with dark field microscopy. Luminescence of the cells varies with species, geographic location, and developmental stage of the tadpoles.
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  • 195
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    Journal of Morphology 184 (1985), S. 351-360 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Serial sections of 13 embryos and fetuses of the harbor porpoise from 10 mm crown-rump length up to 167 mm total length were studied. Unlike the adult animals, ontogenetic stages of 18-27 mm crown-rump length still show a typical mammalian olfactory bulb. The olfactory bulb primordium is penetrated by olfactory nerve fibers, the latter passing through the cribriform plate. However, the olfactory bulb anlage is gradually reduced in later stages, its placodal component being largely uncoupled from the telencephalon. As a ganglionlike structure, the remains of the placodal component stay in contact with the nasal septum and mucosa via thin bundles of nerve fibers. The ganglion and plexus can be traced within the meninges until the adult stage of the porpoise. There is strong evidence that they represent the material of the terminalis system, which cannot be distinguished from the olfactory system in earlier stages. A vomeronasal organ could not be detected in the embryonal and fetal material investigated.
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  • 196
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    Journal of Morphology 184 (1985), S. 361-373 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The kidneys of Phoca hispida are comprised of many closely adherent renculi, each of which is a small kidney, functionally independent of its neighbours except with respect to venous drainage. Venous blood from the rencular parenchyma drains to the periphery through interlobular veins. These interlobular veins empty into a perirencular plexus comprised of subcapsular veins on the free surface of the renculus, interrencular veins on adjoined surfaces, and marginal subcapsular veins lying in the furrows between adjoined renculi. A pericapsular plexus of large veins overlies the marginal subcapsular veins and has frequent connections with them. Blood drains from the pericapsular plexus into large superficial collecting veins that converge over the surface of the kidney toward the divided hilum and connect directly to the paired trunks of the posterior vena cava. There are also connections to other major venous systems of the region.There is no arcuate venous system, no major vein at the rencular hilum, and no vein of consequence emerging from the renal hilum. Venous outflow is virtually entirely directed to the peripheral plexuses. The venous pattern differs from that of most mammals in which blood drains from the renal parenchyma to arcuate veins and leaves the kidney through a renal vein, or veins, emerging from the hilum.The walls of veins in the kidney are remarkably thin in comparison to their size. Subcapsular veins up to 0.5 mm wide have walls on the parenchymal side that in places consist only of a thin, fenestrated endothelium and a basal lamina.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
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  • 197
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 185 (1985) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 198
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 184 (1985), S. 375-387 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Length-force relations, both active and passive, and twitch contraction characteristics were quantified for the entire complex of the superficial calf muscles, as well as individually for the Mm. soleus, plantaris, and gastrocnemius, caput mediale and laterale, of eight male Wistar rats. The M. soleus composes approximately 5% of the weight and cross-sectional area of the entire group of superficial calf muscles and is the only muscle of the group containing mainly slow-twitch fibers. The other superficial muscles of the calf are primarily fast-twitch muscles.The mono-articular M. soleus, the bi-articular M. gastrocnemius, caput mediale and laterale, and the poly-articular M. plantaris differ with respect to the number of joints crossed. However, contrary to the findings for cat hind limbs (Goslow et al. [1977] J. Morphol. 153:23-38), the muscles of the complex of superficial calf muscles of the rat did not differ with respect to (a) their fiber optimum length, (b) their maximum length range of active force generation, (c) the relative increase of passive force owing to lengthening of the muscle, (d) the angle of the ankle at which they produce maximal active force (the knee angle was fixed at 90°).
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 199
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 185 (1985), S. 51-58 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Calcium is demonstrated by energy and wavelength dispersive X-ray microanalysis to be the major component of the granules that fill the fuselli of the organ of Bellonci in Gammarus setosus. The presence of calcium was confirmed by chelation with EDTA and by other cytochemical techniques. X-ray microanalysis indicated the simultaneous presence of iron in the region of the fuselli occupied by the calcium granules, but this could not be confirmed by cytochemical means in resin-embedded tissue by light or transmission electron microscopy.
    Additional Material: 14 Ill.
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  • 200
    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 reports on the spermiogenesis and spermatozoa of seven labidognath spiders: Filistata insidiatrix (Filistatidae), Segestria senoculata (Segestriidae), Dysdera sp., Harpactea hombergi (Dysderidae), Oonops domesticus (Oonopidae), Scytodes thoracica (Scytodidae), and Pholcus phalangioides (Pholcidae). Filistata insidiatrix is the first cribellate spider whose spermatology is described electron microscopically. A common characteristic of the spermatozoa of the cribellate spider and the remaining species, often referred to as haplogyne spiders, is the coiling process that occurs at the end of spermiogenesis. As a result of coiling, an elongated spermatid is converted into a lens-shaped structure with the flagellum bearing a 9 × 2 + 3 axoneme becoming incorporated into the cell body. Remarkable differences regarding the main components (shape of nucleus, acrosomal vacuole, implantation fossa, and centriolar complex) probably reflect systematic relationships.The formation of sperm capsules and sperm balls is described for the first time in detail. Sperm capsules occur in Filistata, in which numbers of individual spermatozoa are grouped together by a common secretory envelope established in the distal vas deferens. In contrast, in the sperm balls, two (Harpactea) or four (Segestria, Dysdera, Seytodes) spermatids fuse completely at the end of spermiogenesis. These sperm balls, considered unique in the animal kingdom, are also provided with an envelope. A further peculiarity not reported previously is the occurrence of a large vesicular area in the sperm balls of Dysdera and Harpactea; this area is also found in Oonops, which, however, possesses individual spermatozoa. Components of the spermatozoa such as the acrosomal vacuole, part of the nucleus, and the axoneme protrude into this area and are thus secondarily covered with a membrane.A detailed study of the individual spermatozoa of Pholcus phalangioides completes earlier investigations and stresses the exceptional position of the genus in comparison to that of other spiders.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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