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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 16 (1978), S. 47-57 
    ISSN: 1432-0630
    Schlagwort(e): 32 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Analytical results have been obtained for some aspects of polyatomic molecular interaction with resonant ir laser radiation. The following effects are investigated by use of Schrödinger's equation solution for natural multilevel models: the role of dynamic Stark effect in the transient region from molecular low levels to the quasi-continuum of highly excited vibrational levels; broadening of multiphoton transitions because of relatively fast decay into the quasi-continuum; threshold excitation property of multilevel systems with random detunings. Possible applications to constructing models for numerical calculations dealing with the molecule excitation problem are discussed.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 20 (1979), S. 291-294 
    ISSN: 1432-0630
    Schlagwort(e): 42.65 ; 82.50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Two photon excitation by a tunable dye laser is used to determine the decay kinetics of some aliphatic tertiary amines. The feasibility of obtaining laser action from trimethylamine and triethylamine by KrF laser pumping is quantitatively discussed.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 17 (1978), S. 151-154 
    ISSN: 1432-0630
    Schlagwort(e): 33 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Lines of theQ-branch of vibrational rotational spectra are distinguished fromP(R)-lines by light induced anisotropy in absorbing gases. We report, for the first time, on experiments using a linearly polarized saturation beam. A CO2-laser was employed to investigate the molecule SF6.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 17 (1978), S. 199-201 
    ISSN: 1432-0630
    Schlagwort(e): 32 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Lamb-dips have been observed in the weak calcium intercombination line by monitoring resonance fluorescence in an atomic beam excited by light of a stabilized cw dye laser inside or outside the laser cavity. A highly sensitive detection scheme is described.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 24 (1981), S. 71-84 
    ISSN: 1432-0630
    Schlagwort(e): 32 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract We consider cooling of a trapped particle in the limit when the position and velocity variables do not change adiabatically. The slowly varying quantity in a harmonic trap is then the energy, and a representation based on oscillator eigenstates is used. For large excitation, fast particles, a Fokker-Planck expansion is obtained which is valid when our adiabatic description breaks down. Estimates of the initial cooling rate are given and compared with earlier results. Our treatment requires a large number of oscillator states to be coupled by each one-photon process, and in this limit the diffusion will make the expansion invalid towards the end of the cooling; our physical interpretation is that particles leak out of the trap. The opposite case, the Lamb-Dicke regime, is advantageous for cooling experiments, and then a difference equation replaces the Fokker-Planck equation of the present paper.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 13 (1977), S. 159-163 
    ISSN: 1432-0630
    Schlagwort(e): 42.65 ; 32
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Two-photon resonant four-wave mixing has been studied both theoretically and experimentally. Tunable infrared radiation between 2 and 20 μm has been generated in potassium and caesium vapours. The mixing efficiency is found to be severely limited by competition with Raman scattering.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 13 (1977), S. 271-280 
    ISSN: 1432-0630
    Schlagwort(e): 32.20 ; 42.10 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract This paper analyses effects related to the real part of the gaseous electric susceptibility in microwave-microwave and infrared-microwave double resonance experiments on two transitions with a common level. The most interesting features are obtained when the gaseous refractive index is probed far off resonance, i.e. in the tail of the dispersion characteristic and when the pump frequency is scanned around the resonance: a resonant change of the refractive index for the probe field is observed, the shape of which is that of the saturated pump line. A calculation using a model of strong collisions gives results in good agreement with the experimental ones. Applications of these phenomena to the determination of frequencies and transition matrix elements of infrared lines are discussed in the general case of lack of overlapping of the laser gain profile and of the infrared line. It is proposed to use these dispersion effects to detect Doppler-free infrared two-photon molecular absorption.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 14 (1977), S. 65-77 
    ISSN: 1432-0630
    Schlagwort(e): 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract We have studied experimentally self-focusing of light in the liquid crystalline mediump-ethoxybenzyldine-p-butylaniline (EBBA). By variation of temperature, the response time of the field-induced refractive index was adjusted from larger than to smaller than theQ-switched laser pulsewidth. Accordingly, self-focusing varied from transient to quasi-steady-state. The results agree well with existing theoretical predictions and can be qualitatively understood from a simple physical description. The induced stimulated Brillouin scattering was also measured and was shown to be responsible for the limiting diameter of the self-focused beam in the present case.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 15 (1978), S. 209-211 
    ISSN: 1432-0630
    Schlagwort(e): 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Continuous coherent radiation in a gas observed in a spacially separated standing wave fields is reported for the first time. The radiation was observed in the center of lineF 2 (2) in methane at the interaction of atoms with two standing waves separated by the distance of 3.5 cm.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 15 (1978), S. 219-222 
    ISSN: 1432-0630
    Schlagwort(e): 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The paper investigates the observation of coherent radiation in separated fields for the case of two-level atoms. The coherent radiation is due to polarization transfer at large distances. The Doppler phase angle is cancelled due to a phase jump at the nonlinear interaction of the fields with the atoms. A peak in intensity with a width inversely proportion to the flight time arises at the line center.
    Materialart: Digitale Medien
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  • 11
    ISSN: 1432-0630
    Schlagwort(e): 42.65 ; 32
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Coherent radiation at 89.6 nm has been obtained through third-harmonic conversion of the 268.8 nm pulses in mercury vapors. Tunability of the fourth-harmonic frequency of the Nd: glass laser radiation to the 6s 1 S 0–8s 1 S 0 double quantum resonance of Hg atoms has been used for the resonant enhancement of the twelfth-harmonic output. Possibility to phase match the generated radiation and driving polarisation in pure vapors without employing of bufer gas has been demonstrated.
    Materialart: Digitale Medien
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 15 (1978), S. 439-450 
    ISSN: 1432-0630
    Schlagwort(e): 42.55 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract A theoretical model for the ultrashort-pulse (USP) generation by lasers with saturable absorbers is presented. The gain medium is assumed to be a two-level system whereas the absorber is described by a four-level system which is characterized by a two-stage absorption process and the pertinent relaxation times. Laser dynamical equations are developed in the rate-equation approximation and boundary conditions appropriate for an unidirectional ring cavity are established. Evolution of USP is investigated for different combinations of parameter values appropriate for solid-state laser systems by computer simulation, employing a finite difference approximation for the dynamical equations. It is shown that USP output is attainable even if the cross-section of the excited-state absorption isgreater than that of the ground-state absorption and the laser is operating just above threshold. In fact, it is found that through the participation of a strong excited-state absorption the discrimination against satellite pulses is enhanced so that single-pulse output is more achievable. Furthermore, it is proposed that single picosecond pulses may be obtainable from relatively broad initial peaks by utilizing the high pulse-selection and pulse-shortening efficiency of the absorber due to the contribution of the excited-state absorption. The applicability of the present model to singlet-triplet crossing and photoisomer formation is also discussed.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 16 (1978), S. 235-237 
    ISSN: 1432-0630
    Schlagwort(e): 32 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract J-dependence of intensity-dependent polarization change of the elliptically polarized light in atomic resonance lines is studied both theoretically and experimentally.
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 16 (1978), S. 151-154 
    ISSN: 1432-0630
    Schlagwort(e): 42.65 ; 42.55 ; 33
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract We observed tunable UV radiation down to 175 nm by SRS of the output of a frequency-doubled dye laser in H2. The high power output of the 4th anti-Stokes to 5th Stokes line generated by the frequency doubled dye laser and the 8th anti-Stokes to 3rd Stokes line generated by the undoubled dye laser represents a broadly tunable coherent radiation source between 189 nm and 2064 nm.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 18 (1979), S. 195-198 
    ISSN: 1432-0630
    Schlagwort(e): 33.20F ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Coherent Stokes Raman spectra of the ν1 and ν3 bands of CH4 have been recorded in mixing two pulsed lasers (ruby and dye) of very good spectral and spatial quality. The results show a resolution of about 0.010 cm−1 for a 10 Torr pressure, corresponding in great part to Doppler broadening.
    Materialart: Digitale Medien
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 15 (1978), S. 213-218 
    ISSN: 1432-0630
    Schlagwort(e): 42.65 ; 42.80 ; 32
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The Wiener functional expansion method for the analysis of nonlinear systems is applied to identify and analyze both nonlinear and linear molecular systems by spectroscopic methods. As the sampling filter (monochromator) of any spectroscopic apparatus may be defined by a Weber-Hermite polynomial, an analysis of the refracted or scattered light by orthogonal polynomials is easily achieved. Time averaging obtains the Weber-Hermite coefficients which permit the characterization of the molecular system with respect to the polarization of the incident and scattered light. In the case of two series of measurements made with incident and emerging light polarized in different directions: the identification of the JonesM matrices for the molecular system irradiated is possible. In the case of three series of measurements made, for example, with incident and emerging light (a) circularly polarized corotating, (b) circularly polarized contrarotating, and (c) plane polarized perpendicular: the identification of the molecular system's McClain invariants related to the vibrational symmetry group for Raman inelastic light scattering is possible. The analysis presents a unified picture of elastic and inelastic light scattering and one-photon and two-photon processes. The apparatus described would detect those instances in molecular systems for which Beer's law does not apply.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 17 (1978), S. 53-62 
    ISSN: 1432-0630
    Schlagwort(e): 42.10 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The coherent interaction of short optical pulses with a nonlinear active resonant medium is calculated. The rigorous and self-consistent solution of the coupled nonlinear Maxwell-Bloch equations including transverse and time-dependent phase variations predicts the onset on an on-resonance self-focusing that agrees very well with a previous perturbation treatment and with recent experiments in sodium and neon. The formation of this dynamic self-action effect is elucidated as being due to the combined effects of diffraction and the inertial response of the active media. Accuracy and computational economy are achieved simultaneously by redistributing the computational grid points according to the physical requirements of the problem. Evenly spaced computational grids are related to variable grids in physical space by a range of stretching and rezoning techniques including adaptive rezoning where the coordinate transformation is determined by the actual physical solution.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 17 (1978), S. 73-77 
    ISSN: 1432-0630
    Schlagwort(e): 42.65 ; 52
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The effect of self-focusing of a high-power light beam with an elliptical cross-section in a strongly ionised plasma has been evaluated. The mechanism of self-focusing considered is non-uniform heating of plasma by an electromagnetic wave having transverse variation of amplitude along its wave front. The heating causes redistribution of carriers which lead to a nonlinear relationship between the electron density and the electric vector and hence to a field-dependent effective dielectric constant. It is found that the beam gets focused at different focal points in different directions exhibiting the effect of astigmatism. There are several critical powers, below thex=0,y=0 planes; at higher powers one dimension focuses while the other defocusses, an oscillatory waveguide is formed in both dimensions. Above the highest critical power both dimensions self-focus, the dimensionless beam width parametersf 1 andf 2 forx andy focusing reach different minima corresponding to different self-focusing distances beyond which both dimensions continue diverging. The effect of energy loss through absorption from the beam has also been considered. It has been observed that absorption brings about a reduction in the extent of self-focusing and favours defocusing of the beam.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 24 (1981), S. 119-120 
    ISSN: 1432-0630
    Schlagwort(e): 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract A technique of fast deep cooling of atomic or molecular buffer gases by laser radiation is proposed. With Na vapor as a cooling agent interacting with a laser field a cooling time of about 10−3s and minimum temperature of about 25K can be attained.
    Materialart: Digitale Medien
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 20 (1979), S. 287-290 
    ISSN: 1432-0630
    Schlagwort(e): 42.65 ; 82.50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The cross-sections of excited-state absorption have been measured for several tertiary amines. The high values found explain the unsuccessful attempts to obtain laser action in KrF-laser pumped vapors of tertiary amines.
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 19 (1979), S. 1-17 
    ISSN: 1432-0630
    Schlagwort(e): 07.65 ; 42.65 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The noise characteristic of available laser sources limits the sensitivity of many types of nonlinear spectroscopy. We show how to maximize the sensitivity by optimizing the strength of a local oscillator wave in a heterodyne detection scheme without altering the amplitude of the wave being detected. The intensity profile of the optimum local oscillator closely matches that of the incident probe wave, but the optimum intensity is much less than that of the probe under realistic conditions. A general signal-to-noise analysis applicable to all nonlinear spectroscopy techniques is presented along with specific applications to coherent Raman spectroscopy, two-photon absorption, saturation spectroscopy, and optical coherent transient techniques. A simple optimization procedure employing polarization selection rules is described. Detailed calculations are performed for the case of TEM00 waves interacting via a third-order nonlinear susceptibility and for the case where the sample is simultaneously probed at many different frequency combinations.
    Materialart: Digitale Medien
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 24 (1981), S. 89-106 
    ISSN: 1432-0630
    Schlagwort(e): 33 ; 42.65 ; 82.50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract A review of laser-induced photoionization of polyatomic molecules and the application of this process in mass-spectrometry is presented. Combination of laser selective photoionization and mass spectral analysis of fragments as a promising tool for the detection of trace amounts of complex molecules is considered particularly.
    Materialart: Digitale Medien
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 24 (1981), S. 349-355 
    ISSN: 1432-0630
    Schlagwort(e): 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract We construct field equations and generalised Bloch equations for multiphoton processes involving the coherent interaction of a number of distinct electric fields with an arbitrary number of atomic eigenstates, and apply the equations to some physical examples. Transient stimulated hyper-Raman scattering, in the low-conversion regime and far from saturation, has been studied analytically. Assuming that the pump pulse interacts with the medium byn-photon absorption, we find expression for the intensity of the generated Stokes pulse.
    Materialart: Digitale Medien
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  • 24
    ISSN: 1432-0630
    Schlagwort(e): 42.60 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract In this paper we describe the construction of a monochromatic and frequency stabilized continuous wave (cw) source in the 5 μm region. It is built up by a cw single line, single-mode frequency and amplitude stabilized CO2 laser. This primary CO2 laser source is then frequency-doubled in a tellurium crystal using second harmonic generation (SHG). The obtained emission is monochromatic (half-width 50 kHz). The frequency can be varied discreetly from 4.6 μm to 5.5 μ depending on the CO2 laser line chosen.
    Materialart: Digitale Medien
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 24 (1981), S. 11-12 
    ISSN: 1432-0630
    Schlagwort(e): 42.65 ; 07.65 ; 33.90
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Experimental observation of optical Ramsey interference in saturated absorption of methane in a low-pressure gas cell with three spacially separated laser beams at 3.39 μm is reported.
    Materialart: Digitale Medien
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 25 (1981), S. 31-34 
    ISSN: 1432-0630
    Schlagwort(e): 35 ; 42.55 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The decay rates of the3 D 1 level of I–II and the 3s 2 level of neon have been measured by the magnetic-field power dip method. The decay rate at the zero-pressure limit is found to be 7.1 MHz/2π for the3 D 1 level. The collision cross-section for excited I ions with helium atoms equals 0.19×10−15 cm2.
    Materialart: Digitale Medien
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  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 25 (1981), S. 49-56 
    ISSN: 1432-0630
    Schlagwort(e): 42.65 ; 78.20
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Four-wave mixing with two circularly polarized counter-propagating waves inducing a helical birefringence structure can be used to measure a number of material parameters of a liquid crystalline medium. Application to a cholesteric substance is particularly interesting. A resonant effect is expected when the induced helix has a pitch coinciding with the natural helical pitch of the medium towards the isotropic → cholesteric transition. Field-induced shift in the transition temperature is also expected.
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 26 (1981), S. 185-190 
    ISSN: 1432-0630
    Schlagwort(e): 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Optical frequency mixing through nonlinear mode coupling in a planar waveguide, fabricated with a cubic or uniaxial dielectric, is discussed. A threewave interaction is examined and the optimum crystal orientations that lead to the highest efficiency are determined in those particular cases in which they do not depend on the field distribution of the modes. The analysis is carried out in detail for cubic crystals; sensitivity to misalignments is also studied and numerical results are reported.
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 14 (1977), S. 403-410 
    ISSN: 1432-0630
    Schlagwort(e): 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The nonlinear optical susceptibility tensors of barium formate (point group 222) and magnesium barium fluoride (point group mm 2) have been determined by the method of Maker fringes on the basis of a more rigorous theoretical treatment of second-harmonic generation of electromagnetic waves in plane-parallel plates of optically biaxial crystals. The measurements have been carried out in comparison with the KDP standard at awavelength of 1.064 μm (Nd: YAG). Both crystals possess nonlinear coefficients smaller than KDP (d 36); they are phase matchable; magnesium barium fluoride exhibits a noncritical phase matching at a fundamental wavelenght of 1.04 μm.
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  • 30
    ISSN: 1432-0630
    Schlagwort(e): 32 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The paper presents the results obtained in investigating the lineshape of two-photon absorption in the field of two spacially separated standing waves at the 3S–4D transition of Na. Measurements were carried out by using a CW dye laser.
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  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 15 (1978), S. 99-102 
    ISSN: 1432-0630
    Schlagwort(e): 42.65 ; 78.20
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Comparing the recombination light intensity produced in GaAs by a 1.06 μm pulse inducing two-photon absorption, with the intensity produced by a 0.53 μm pulse, we obtain directly the two-photon absorption cross-section. This method can be generalized to other materials.
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  • 32
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 14 (1977), S. 289-294 
    ISSN: 1432-0630
    Schlagwort(e): 79.70 ; 42.65 ; 85.60
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract In a series of recent experiments, research groups have made absolute frequency measurements with laser beams in the infrared region (μm) using a metal-metal point contact diode for the generation, frequency mixing and detection. At present there are two models which attempt to explain the rectification mechanism of the diode: 1) Tunneling of electrons through an intermediate oxide film from whisker to the metal base, i.e., configuration is considered to be a metal-oxide-metal (MOM) tunneling junction. 2) Rectification and nonlinear processes are the result of a thermal enchanced field emission. Such emission is a consequence of the immersion of the whisker in the laser radiation which results in conduction induced thermionic emission and/or generation of an electric field at the tip necessary for electron tunneling by field emission. The purpose of this comment is: a) to discuss qualitatively the basic difference between MOM and TFE theories as regards the origin of the nonlinearity and rectification properties of the metal point contact junction; b) to review the analyses describing the ultimate frequency response of the device; and 3) to provide a possible explanation for polarity reversal consistent with the TFE mechanism describing the operation of the whisker diode.
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 19 (1979), S. 39-41 
    ISSN: 1432-0630
    Schlagwort(e): 42.55 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract It is shown that when a distributed feedback dye laser is used to generate a train of picosecond pulses, the narrow lines observed in the spectrum are not longitudinal modes, but are due to the intrapulse refractive index changes caused by the heating effect of the pumping pulse.
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  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 19 (1979), S. 221-224 
    ISSN: 1432-0630
    Schlagwort(e): 42.10 ; 42.55 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Wave front of a light pulse is shown to be unstable as it propagates through a resonant saturable absorber, if its frequency is higher than the resonance frequency of the absorber. When ΔωT 2∼1, a small-scale transverse instability with the dimension of (λl abs)1/2 grows rapidly. Its growth-rate is of the order of the small-signal-absorption length of the medium.
    Materialart: Digitale Medien
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  • 35
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 19 (1979), S. 321-329 
    ISSN: 1432-0630
    Schlagwort(e): 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract A time-sinusoidal circularly polarized plane standing wave solution is obtained for isotropic lossless dielectric media with arbitrary nonlinearity. The spatial variation of the standing wave depends on the nonlinearity and is found by solving a problem of centralforce motion in which the electric complementary energy density furnishes the potential and the spatial coordinate has the role of time. Two special nonlinear dielectric response laws-cubic and quintic-are treated, and explicit solutions for the spatial variation of the wave amplitude and phase are obtained in terms of elliptic functions and elliptic integrals, respectively. The standing-wave solution is applied to give steady state solutions of two reflection/transmission problems (a) reflection from, or resonance modes between, ideally conducting planes and (b) reflection and transmission at a plane interface between two nonlinear dielectric media.
    Materialart: Digitale Medien
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  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 24 (1981), S. 45-48 
    ISSN: 1432-0630
    Schlagwort(e): 42.55 ; 42.65 ; 64
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract We investigated time-dependent effects related to the bistable operation of a CO2 laser with an intracavity nonlinear absorber (SF6). The response of the system to small perturbations was sensitively dependent on the operating laser line [P(12)→P(30)] of the 10.6 μm band. The narrow bistable region forP(12), due to a very narrow hysteresis loop, can be effectively utilized for optical switching, because of its pronounced sensitivity to variations in operational parameters. The maximum admissable beam blocking time (intracavity) for spontaneous return to lasing was measured forP(16), for a range of absorber pressures. This τm is related to the relaxation time of the upper level in the absorber.
    Materialart: Digitale Medien
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  • 37
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 24 (1981), S. 139-142 
    ISSN: 1432-0630
    Schlagwort(e): 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The tuning and threshold behaviors of 5P 1/2–5P 3/2 stimulated electronic Raman scattering in In vapor were investigated. The Stokes output intensity was limited by atom depletion process in the atomic density available for the measurement. The anti-Stokes radiation observed was studied in terms of the phase matching condition.
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  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 24 (1981), S. 151-162 
    ISSN: 1432-0630
    Schlagwort(e): 32 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract In this paper we consider the laser cooling of a trapped particle when the discrete nature of the quantum levels must be taken into account. We particularize the equations to the Lamb-Dicke limit when the oscillational, amplitude is much less than the optical wavelength. Then the quantum levels are coupled only to the neighbouring ones, and we can also find a small parameter to use for adiabatic elimination of rapidly varying terms. There emerges one rate equation for the probability distribution over the quantum states. The ultimate distribution is found to be of the Planckian type independently of the initial one. We solve the equation, generally and obtain the time evolution for an arbitrary initial distribution. In particular we look at an initially thermal, Poisson, or pure state distribution. For the thermal one we find that its shape is preserved during the cooling. The results are discussed.
    Materialart: Digitale Medien
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  • 39
    ISSN: 1432-0630
    Schlagwort(e): 42.65 ; 71.20
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract We studied the change in Spin-flip Raman (SFR) gain and behaviour of the effectiveg-value as a function of pulsed electric fields inn-type InSb. The samples were held at 1.8 K in magnetic fields up to 1.4 T. Varying the strength of a pulsed electric field applied to the samples parallel to the magnetic field we found a direct correlation between the increase in electron temperature and the decrease of the Raman gain. Measurements of the Raman gain and spontaneous line width at different times after the starting of the electric pulse and during its fall time with a time resolution of 10 ns give no indication of a motional narrowing of the SFR line and of an increase of the gain during the decrease of the electric field pulse. These two predictions were made by Mooradian et al. (1972) to explain the observed transient increase of the intensity of the stimulated SFR Stokes radiation after an electric field across the sample was switched off. With our direct measurement of the Raman gain we could establish that at any time during and after the electric field pulse, the gain is less or equal to the value without electric field. In the electric field region from 0.3 V/cm up to 0.6 V/cm the Raman gain shows several maxima, originating from SFR scattering between different spin splitted conduction band levels. The electron distribution under pulsed electric field conditions give rise to a dynamically varying absorption mechanism of transmitted radiation. Time resolved transmission measurements explain the observed increase of stimulated SFR Stokes radiation during the switch-off time of electric field pulses by a lower absorption of radiation and not by a larger gain.
    Materialart: Digitale Medien
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  • 40
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 14 (1977), S. 377-380 
    ISSN: 1432-0630
    Schlagwort(e): 42.55 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Due to spatial hole burning, standing-wave dye lasers require a large amount of selectivity inside the cavity for single-mode operation. The output power of these lasers is limited by losses caused by the frequency selecting elements. In a travelling-wave laser, on the other hand, spatial hole burning does not exist, thereby eliminating the need for high selectivity. A travelling-wave cw dye laser was realized by unidirectional operation of a ring laser, yielding single mode output powers of 1.2 W at 595 nm and of 55 mW in the UV-region with intracavity frequency doubling.
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  • 41
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 15 (1978), S. 53-57 
    ISSN: 1432-0630
    Schlagwort(e): 71.20 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract In this paper we report on measurements of spin-flip-Raman gain inn-InSb as a function of the magnetic field. The measurements were carried out at temperatures of 1.8 K and 4.2 K and at a carrier concentration of 1.35×1015 cm−3. The Raman cross sections obtained from these results, e.g. 1.25×10−20 cm2/sr at a magnetic field of 10 kG and a pump frequency of 1884.35 cm−1, agree very well with those theoretically predicted by Wherrett and Wolland. Furthermore, these measurements yield line shapes and linewidths of the spontaneous scattering (100–1500 MHz) and allow the determination of the effectiveg-value with an accuracy known from ESR-investigations. These results are discussed in terms of already published theoretical investigations.
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  • 42
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 15 (1978), S. 319-322 
    ISSN: 1432-0630
    Schlagwort(e): 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract This paper reports on an experimental observation of coherent radiation after interaction with two standing-wave pulses having the time delayT in an absorbing rarefied gas. The radiation appears at the time 2T, 3T,... after the first pulse. The coherent radiation arises due to spacial transfer of polarization and to formation of a spacial polarization harmonic owing to a phase jump after two-photon interaction with the field of the second pulse. We observed intensity oscillations with frequency tuning of the exciting laser, varying the time delay between pulses.
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  • 43
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 17 (1978), S. 423-424 
    ISSN: 1432-0630
    Schlagwort(e): 42.65 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract An optical arrangement for studying two-photon absorption in liquids is presented. The main feature of this new arrangement is fuller utilization of fluorescence light. This makes possible application of very low power cw laser in such experiments.
    Materialart: Digitale Medien
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  • 44
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 14 (1977), S. 155-159 
    ISSN: 1432-0630
    Schlagwort(e): 42.65 ; 71.20
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract We report for the first time stimulated magneto-Raman scattering inp-type InSb. Two different Raman scattering processes were observed. The first one has a Raman shift of about 2cm−1/kG and is observed at magnetic fields up to 30kG. The other one is observable only at high magnetic fields above 30kG and shows Raman shifts between 1.2cm−1 and 3.0cm−1 with a tuning rate of about 0.2cm−1/kG. The first process can be interpreted either as spin-flip Raman scattering by photo-excited electrons in the conduction band or as Raman scattering by holes in the valence band involving transitions from heavy to light hole states. The other Raman shift observed seems to occur on account of transitions between the heavy hole ladders.
    Materialart: Digitale Medien
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  • 45
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 17 (1978), S. 393-400 
    ISSN: 1432-0630
    Schlagwort(e): 42.55 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Stimulated Raman scattering by polaritons when employing a nonlinear crystal inside the cavity of the laser with Q-switching and locked to fundamental frequency was theoretically studied. The equations were formulated describing the dynamics of the fundamental, Stokes and polariton waves under the assumption of instant Q-switching and uniformity of radiation except in the longitudinal direction. Numerical solutions of the equations were found and analysed. We demonstrate the influence, on generation characteristics, of the most important parameters, such as the effective nonlinearity, the initial level of population inversion, the feedback of the Stokes wave and the group mismatch between a Stokes and a pump wave. Optimum generation conditions are determined. Possibilities of the method are discussed for the generation of a) giant pulses which are controllable with regard to carrier frequency and duration but are unachievable with other methods, b) Stokes pulses of very small duration and high energy having sharp trailing edges, and c) analogous polariton pulses in the middle and far infrared range. The generation using a number of polariton branches in LiNbO3 was considered as an example. Calculations are in qualitative agreement with experimental data.
    Materialart: Digitale Medien
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  • 46
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 18 (1979), S. 271-274 
    ISSN: 1432-0630
    Schlagwort(e): 42.65 ; 64 ; 77.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The temperature-dependent optical second-harmonic generation in thermally depoled La-doped lead zirconate titanate (PLZT) ceramics of composition 8/65/35 and 9/65/35 has been studied. A microscopic model for the anomalous phase transition behaviour of these compounds is suggested.
    Materialart: Digitale Medien
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  • 47
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 17 (1978), S. 211-232 
    ISSN: 1432-0630
    Schlagwort(e): 42.55 ; 42.65 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Physical principles, new ways and means of creation, schemes, characteristics and features of efficient high-power tunable pulse Raman lasers, operating in the near and middle ir are reviewed. The paper includes: tunable dye and Nd lasers as pump sources; promising active media and their optimal excitation methods; optical systems for producing spatially homogeneous pumping; the physics of Raman oscillators and their practical schemes, efficient high pulse energy liquid N2 and compressed H2 Raman oscillators, covering several bands in the range between 1.4 and 9.2 μm; the physics and construction of efficient tunable Raman amplifiers-convertors, amplifying in the saturation regime of spontaneously scattered or beforehand produced and collimated external Stokes signals, obtained in the spectral range between 0.83 μm and 18 μm. Raman laser using a, so-called, broadband pump where the linewidth of pumping light is broader than the spontaneous scattering linewidth, are also discussed. Features of both amplification and oscillation regimes of such broadband pumped Raman lasers are reported, and conditions for the efficient frequency conversion are determined.
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  • 48
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 24 (1981), S. 303-306 
    ISSN: 1432-0630
    Schlagwort(e): 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract This paper describes the experimental investigation of stimulated Raman scattering obtained from a multimode fiber. 10 orders of stimulated Stokes scattering of wavelengths in the 546–702 nm region were obtained from a 480m multimode, low-loss, graded-index quartz fiber pumped by a 532 nm frequency-doubled YAG-Nd laser beam with a pulse duration of 7 ns, output power of 0.7 MW and repetition rates of 5 and 10 pps.
    Materialart: Digitale Medien
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  • 49
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 18 (1979), S. 177-181 
    ISSN: 1432-0630
    Schlagwort(e): 42.55 ; 42.65 ; 33
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract We have studied experimentally stimulated Raman scattering and 4-wave-interaction processes occuring in hydrogen gas, which is excited by a Nd:YAG-pumped dye laser. The tuning ranges of the various Stokes and anti-Stokes lines, which are generated with high efficiency, cover the spectrum from 185 to 880 nm without a gap.
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  • 50
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 20 (1979), S. 319-323 
    ISSN: 1432-0630
    Schlagwort(e): 33 ; 42.65 ; 42.80
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The suitability of a singly resonant optical parametric oscillator pumped by a one-mode field and oscillating simultaneously in several signal and idler modes, for intracavity absorption spectroscopic measurements is studied theoretically. For steadystate operation, the enhancement factor ξ indicating the increased detection sensitivity, is shown to be mainly determined by the ratio of the intensity in one of the signal modes to the intensity (per mode) due to parametric fluorescence. Hence, rather high values of ξ, say of order 108 or more, might be attainable, at least in principle. For pulsed operation, on the other hand, a numerical analysis leads to the result that for realistic pulse durations only moderate values of ξ (smaller than some 103) will be found.
    Materialart: Digitale Medien
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  • 51
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 19 (1979), S. 127-130 
    ISSN: 1432-0630
    Schlagwort(e): 42.55 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The possibility of using stimulated emission from the recombination of electron-positron pairs for obtaining coherent γ-rays is considered. The critical number of pairs needed for the process is calculated.
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  • 52
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 20 (1979), S. 247-250 
    ISSN: 1432-0630
    Schlagwort(e): 33 ; 42.65
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The optically induced polarization change was studied in the case of a standing elliptically polarized wave. Using a Zeeman-tuned gas laser at 3.39 μm with an internal methane cell we have demonstrated the influence of the dichroism on the nonlinear absorption signals.
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  • 53
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 20 (1979), S. 261-264 
    ISSN: 1432-0630
    Schlagwort(e): 42.65 ; 42.55
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The method of Stimulated Mandelshtam-Brillouin Scattering (SMBS) is utilized in a powerful laser to obtain better transverse beam quality by phase conjugation. The principle is explained, and the conclusions are substantiated by experimental results.
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  • 54
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 27 (1979), S. 33-40 
    ISSN: 1432-0827
    Schlagwort(e): Chick embryo ; Bone ; Organ culture ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The study describes the ultrastructure of the mineralized portion of chick tibiae from 10 days in ovo to 2 days post-hatch. At 10 days a single mineralized cylinder surrounds the diaphysis. On its outer surface columnar trabeculae join to form ridges parallel to the long axis of the bone. These ridges are covered by another cylinder and form the haversian canals. At 11 days vascular invasion of the marrow cavity occurs and resorption of the endosteal surface begins. This type of periosteal deposition and endosteal resorption is repeated during and subsequent to embryonic development. The mineralized portion of 10-day chick tibiae cultured for 2 days in modified BGJ medium was compared with 10-, 11-, and 12-day tibiae in ovo. Cultured tibiae were similar in length and calcium content to 11-day tibiae in ovo. The form of mineral deposited in ovo and in culture was the same, namely, aggregates of spherical mineral clusters. Differences in culture included the following: (a) few concentric cylinders were deposited as compared with tibiae in ovo; (b) trabeculae were not arranged in rows and ridges in culture; (c) osteocytic lacunae were restricted to bases of trabeculae rather than uniformly distributed as in ovo; and (d) the endosteal surface of tibiae in culture appeared etched.
    Materialart: Digitale Medien
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  • 55
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 26 (1978), S. 237-241 
    ISSN: 1432-0827
    Schlagwort(e): Epiphyseal chondrocytes ; Freezefracture ; Scanning electron microscopy ; Cell processes ; Membrane particles
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary Chondrocytes in epiphyseal cartilage were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) using freeze-fracture techniques. Freeze-fracture replicas showed large numbers of fingerlike, 0.11–0.15 μm diameter, projections from the chondrocyte surface, with numerous 95–180 Å diameter intramembranous particles associated with both the cell membrane surface and these projections. With SEM, these cytoplasmic projections were also obvious, but appeared collapsed into clusters of globular-shaped projections on the surface of the chondrocytes. With freeze-fracture techniques, in which shrinkage artifacts were essentially eliminated, the cytoplasmic projections were often seen in intimate contact with the extracapsular matrix. However, with chondrocytes prepared by both SEM and conventional TEM, there was evidence of shrinkage, the cytoplasmic projections having little contact with the extracapsular matrix. These findings show that the cytoplasmic processes are not artifacts of tissue processing and provide morphological evidence in support of the hypothesis that matrix vesicles are of cellular origin.
    Materialart: Digitale Medien
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  • 56
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 25 (1978), S. 75-83 
    ISSN: 1432-0827
    Schlagwort(e): Rat ; Fluorosis ; Enamel ; Scanning electron microscopy ; Low temperature incineration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary Sixteen 58-day-old male rats of Wistar strain, with a mean body weight of 179 g, were divided into two equal groups. Each group of eight animals was maintained for 70 days on drinking water, ad lib., containing no fluorine (control group) and 100 ppm of fluorine (experimental group). All specimens examined were obtained from the incisal portions of the incisors. The following types of enamel specimens were prepared for scanning electron microscopy: (1) acid-etched specimens; (2) acid-etched specimens followed by low temperature microincineration; and (3) fractured specimens. The enamel formed during high fluoride exposure showed marked hypocalcification, that is, the crystallite density in the prism core and interprismatic region was lower than that of control animals. The organic substances appeared to increase in these regions. These changes were prominent in the outer and middle enamel layers. Such changes following fluoride administration appear to indicate an inhibition of enamel maturation, that is, an inhibition of the mineral deposition and/or an inhibition of organic matrix withdrawal.
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  • 57
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 24 (1977), S. 223-229 
    ISSN: 1432-0827
    Schlagwort(e): Enamel-cementum-morphology ; Immunocytochemistry ; Biochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary The continuously erupting rabbit incisor tooth is normally thought of as having an enamel covered “crown” on its labial surface and a cementum covered “root” on its lingual surface. We have examined both surfaces of continuously erupting rabbit incisor teeth taken from near term embryos by a variety of means, including transmission and scanning electron microscopy, biochemical fractionation, and immunohistochemistry. In all cases, we could detect no qualitative difference in the early extracellular matrices taken from the labial and lingual surfaces of the teeth. Both matrices were shown to be composed of dentin and enamel, although the thickness and geometry of the enamel matrix on the lingual surface was somewhat different from that on the labial surface.
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  • 58
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 200 (1979), S. 223-227 
    ISSN: 1432-0878
    Schlagwort(e): Hypothalamus ; Lacertilian reptiles ; Vasotocin neurons ; Mesotocin neurons ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The hypothalamic magnocellular neurosecretory system of lizards was studied with the unlabeled antibody peroxidase-antiperoxidase complex (PAP) technique at the light microscopic level. It was shown that vasotocin and mesotocin are synthesized in separate neurons. The vasotocinergic as well as the mesotocinergic perikarya are of different sizes. Both cell types occur in close juxtaposition, but without a distinct pattern of distribution. The external zone of the lacertilian median eminence contains numerous immunoreactive vasotocinergic fibers and only few immunoreactive mesotocinergic fibers. The general organization of the hypothalamic magnocellular neurosecretory system of lizards, as revealed by immunocytochemistry, is essentially similar to that revealed with unspecific staining methods.
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  • 59
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 200 (1979), S. 285-290 
    ISSN: 1432-0878
    Schlagwort(e): Immunocytochemistry ; Ecdysteroids ; Prothoracic gland ; Insect hormones ; Galleria mellonella
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Fixation of prothoracic glands of Galleria mellonella with a solution containing saponin permits immunocytochemical staining of the entire gland. By this means ecdysteroids were demonstrated electron microscopically to be present in the hyaloplasm and microtubules.
    Materialart: Digitale Medien
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  • 60
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 176 (1977), S. 493-504 
    ISSN: 1432-0878
    Schlagwort(e): Pancreas ; Acinar cells ; Cell surface ; Dissociation ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The pancreatic acinar cell surfaces have been studied by SEM with a dissection technique and correlated with results obtained by TEM. The SEM results demonstrate characteristic arrangement of microplicae which in some areas are densely packed. In many areas, the microplicae are distributed in such a manner that they create zones with typical geometrical shapes and show a relatively smooth surface. These smooth areas may coincide, as indicated by correlated TEM results, with the limits of intimate contact between adjacent acinar cells which, in turn, represent part of the junctional complex. Another aspect revealed by these SEM preparations concerns the presence of groups of densely packed microplicae, arranged in regular rows and distributed along some grooves and/or infoldings of the cellular surface. On the basis of SEM and TEM information, it is likely that these structures correspond to intercellular (and possibly, in some cases, intracellular) canaliculi which topographically form a kind of extensive microlabyrinthine arrangement running along all the cell sides. One final point revealed by fractured samples concerns the finding of spherical zymogen droplets within the vesicles of the Golgi complex. Because in many scanning images these vesicles appear connected by small openings, it is suggested that they may represent a system of intercommunicating chambers (vacuoles) through which the zymogen droplets can be continuously accumulated and discharged into the acinar lumen.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 61
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 177 (1977), S. 307-316 
    ISSN: 1432-0878
    Schlagwort(e): Third ventricle ; Mature monkeys ; Scanning electron microscopy ; Ependyma
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Surface features of the ependymal lining of the third ventricle in mature male and female monkeys have been investigated with scanning electron microscopy (SEM). Broad aspects of third ventricular morphology from three species of monkey are similar regardless of sex. The lateral walls are heavily ciliated whereas the ventral floor and most ventral parts of the lateral walls are not. Clumps of cilia on the lateral walls are so dense that underlying surface details are usually obscured. There is a transition zone between the ciliated lateral wall and nonciliated ventral floor. The floor and lower part of the lateral walls of the third ventricle exhibit a characteristic polygonal pattern upon which surface specializations such as microvilli, blebs and polymorphous membrane protrusions are superimposed. Ependyma of the choroid plexus of the third ventricle also display membrane specializations. Supraependymal cells are more visible in nonciliated regions.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 62
    ISSN: 1432-0878
    Schlagwort(e): Enkephalin neurons ; Vasotocin neurons ; Isotocin neurons ; Immunocytochemistry ; Goldfish (Carassius)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Our immunocytochemical investigation of the magnocellular neuroendocrine system in the goldfish hypothalamus reveals enkephalin (ENK)-containing neurons interspersed among the vasotocin (VT)- and isotocin (IT)-containing neurons of the preoptic nucleus. The perikarya of the ENK, VT, and IT neurons do not show distinct morphological differences at the level of light microscopy and are not located preferentially within the nucleus. Separate ENK, VT and IT fibers course laterally and ventrally through the hypothalamus as they descend toward the pituitary gland. All three fiber types form terminals around blood vessels in the neurohypophysis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 63
    ISSN: 1432-0878
    Schlagwort(e): Pancreatic polypeptide (PP) ; Neurones ; Central nervous system ; Peripheral nervous system, gut ; Immunocytochemistry ; Mammals ; Birds
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Pancreatic polypeptide (PP) is a candidate hormone of unknown physiological significance. It is produced by a population of endocrine cells in the pancreas. In the present study a PP-like peptide was found to occur in the mammalian and avian central and peripheral nervous systems. Immunoreactive nerve fibres and nerve cell bodies were widely distributed in the brain. Dense accumulations of nerve fibres occurred in the following areas: nucleus accumbens, interstitial nucleus of the stria terminalis, para- and periventricular hypothalamic nuclei, and medial preoptic area. In addition, nerve fibres were regularly seen in cortical areas. Immunoreactive perikarya were observed in the following regions: cortex, nucleus accumbens, neostriatum and septum. In the gut, immunoreactive nerve fibers were distributed in the myenteric plexus, in smooth muscle, around blood vessels, and in the core of the villi. Immunoreactive perikarya occurred in the submucosal and myenteric plexus, suggesting that PP immunoreactive nerves are intrinsic to the gut. In the species examined, the neuronal PP-like peptide could be demonstrated with an antiserum raised against avian PP, but not with those raised against bovine or human PP. Thus, neuronal PP is distinct from the PP that occurs in pancreatic endocrine cells.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 64
    ISSN: 1432-0878
    Schlagwort(e): Pituitary ; Dexamethasone ; ACTH ; Autoradiography ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary 3H-Dexamethasone (10 μg/kg) was injected intravenously in adrenalectomized rats and after survival times of 5, 30, 60, and 180 min its uptake within the pituitary was studied by autoradiography. Radioactivity was concentrated in cell nuclei in the pars nervosa and pars distalis. Within the pars intermedia, only cells of the marginal zone were labeled. In the pars distalis, some cells showed a weak nuclear accumulation of radioactivity as early as 5 min after injection. The tissue radioactivity was nearly maximal at 5 min, and the proportion of radioactivity in nuclei reached a maximum of 60–70% by 30 min. In competition experiments, non-radioactive steroids (1 mg/kg) were injected 5 min before 3H-dexamethasone and sacrifice was 30 min later. Dexamethasone markedly diminished the nuclear accumulation in the pars distalis, but corticosterone and progesterone did not. In the pars nervosa, corticosterone and progesterone competed for nuclear uptake of 3H-dexamethasone, although less effectively than dexamethasone itself. Different cell types in the pars distalis were characterized by treating autoradiograms with an immuno-peroxidase bridge procedure. Cells treated with anti-ACTH 17–39 had the greatest nuclear concentration of radioactivity, and those stained with anti-TSH were least heavily labeled. Cells treated with antisera to GH, PRL, and hCG were moderately labeled.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 65
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 175 (1977), S. 541-549 
    ISSN: 1432-0878
    Schlagwort(e): Blood vessels ; High voltage electron microscopy ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The luminal surface features and Junctional complexes from developing blood vessels in the rat central nervous system have been studied by high-voltage electron microscopy and scanning electron microscopy. Developing blood vessels exhibit three types of luminal projections; marginal folds or ridges at Junctional complexes, ridges not at Junctional complexes and microvilli. Both types of ridges are associated with troughs or depressions in the luminal surface of the endothelial cell. Those ridges not associated with Junctional complexes take part in the production of enclosed tunnels in the endothelial cell cytoplasm. Fusion of the external leaflets of Junctional complexes between adjacent endothelial cells occurred, initially, near the luminal surface of the blood vessel with other small fusion sites forming in the direction of the basal lamina secondarily. Further fusion activity to produce the zonula occludens type junction appeared to spread outwards from the smaller fusion sites.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 66
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 178 (1977), S. 17-38 
    ISSN: 1432-0878
    Schlagwort(e): Myosin ; Immunocytochemistry ; Adrenal medulla ; Exocytosis ; Secretion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Myosin was isolated in high purity from the bovine adrenal medulla by gel filtration and ion exchange chromatography. The purified myosin was analyzed by electrophoresis in gels containing SDS and found to contain a 200,000 molecular weight heavy chain and major light chains of molecular weights 20,000 and 17,000 in a 1∶1∶1 molar ratio. At high ionic strength the myosin had high Ca-ATPase and K-EDTA-ATPase activities and low Mg-ATPase activity. At low ionic strength, the Mg-ATPase was activated to a low level by rabbit muscle actin. The myosin was found to decorate F-actin in the absence, but not the presence of ATP. In low ionic strength solutions, the myosin assembled into characteristic bipolar filaments. The distribution of this myosin in the adrenal medulla and of cross-reacting myosin in several other bovine tissues was determined with the use of antimedullary myosin immunoglobulin G as a specific stain that was detected by direct and indirect immunofluorescence. In the medulla strong staining was seen between the chords of chromaffin cells indicating the presence of a highly muscular vasculature that may perform functions analogous to those of the myoepithelium of exocrine glands. The chromaffin cells showed weak positive staining around the nuclei and in a pattern radiating toward adjacent blood vessels. Cells of the inner zone of the adrenal cortex showed strong staining in the peripheral cytoplasm while cells in the intermediate and outer zones did not stain. In a blood smear, platelets and the cytoplasm of leukocytes stained strongly while erythrocytes did not stain. In striated muscle and the gray and white matter of the cerebrum only the capillaries and larger vessels stained. In the liver the phagocytic cells bordering vascular sinuses stained strongly while the hepatocytes were separated from one another by a 2 micron trilaminar band possibly representing the microfilament web surrounding the bile canaliculi and associated with junctional complexes. The results suggest that myosin is present in several highly differentiated, non-motile tissue cells where it may play a role in secretion or other specialized functions.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 67
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 200 (1979), S. 29-33 
    ISSN: 1432-0878
    Schlagwort(e): Magnocellular neurosecretory system ; Activation ; Rat ; Vasopressinergic neurons ; Oxytocinergic neurons ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The activated hypothalamic magnocellular neurosecretory system of the rat was studied in tissue sections, double stained with the unlabeled antibody peroxidase-antiperoxidase complex (PAP) technique. The results indicate that in animals with an activated hypothalamic magnocellular neuroendocrine system, as well as in normal animals, vasopressin and oxytocin are exclusively synthesized in separate vasopressinergic and oxytocinergic neurons.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 68
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 200 (1979), S. 409-423 
    ISSN: 1432-0878
    Schlagwort(e): Human placenta ; Classification of villi ; Histology ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The classification of human placental villi was reviewed on the basis of material prepared by means of special methods. The material from in situ normal-term placentae was biopsied by aspiration into glutaraldehyde. The classification was made on the basis of light-microscopic observations of semithin sections, reconstructions from serial sections, and scanning-electron micrographs. The peripheral villous tree is roughly divided into stem (ramuli), intermediate and terminal villi. The intermediate villi may be further subdivided as mature and immature types, which are found between the stem and terminal villi. Some of the terminal villi possess a local specialization described as the neck region. The histological characteristics and the branching pattern of each type are described, and the basis of the proposed classification is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 69
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 182 (1977), S. 139-143 
    ISSN: 1432-0878
    Schlagwort(e): Pineal organ ; Uroloncha domestica (Aves, Passeriformes) ; Photoreceptor-like cells ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the pineal organ of the lovebird, Uroloncha domestica, bulbous, cup-shaped and elongated outer segments of photoreceptor-like pinealocytes are demonstrated by scanning electron microscopy. These scarce outer segments, 4–11 μm in length, extend into the pineal lumen. The present structural observations speak in favor of photosensitive pinealocytes in the pineal organ of Uroloncha domestica. The relation of the photoreceptor-like pinealocytes to acetylcholinesterase-positive nerve cells and a nervous connection between the pineal and the brain indicate that the pineal organ of this passeriform species may be the site of neuroendocrine and photoreceptive functions.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 70
    ISSN: 1432-0878
    Schlagwort(e): Somatostatin ; Somatostatin cells ; Rat stomach ; Paracrine action ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Somatostatin cells in the stomach of the rat have a characteristic shape and distribution. In the antral mucosa they occur together with gastrin cells and enterochromaffin cells at the base of the glands. In the oxyntic mucosa they are scattered along the entire glands with some predominance in the zone of parietal cells. Throughout the gastric mucosa the somatostatin cells possess long and slender processes that emerge from the base of the cell and end in clublike swellings. Such processes appear to contact a certain proportion of neighbouring gastrin cells in the antral mucosa and parietal cells in the oxyntic mucosa. Exogenous somatostatin given by intravenous infusion to conscious rats counteracted the release of gastrin stimulated by feeding, elevated antral pH or vagal excitation. Gastrin causes parietal cells to secrete HCl and endocrine cells in the oxyntic mucosa to mobilise and synthesise histamine. Somatostatin is known to block the response of the parietal cells to gastrin. In contrast, somatostatin did not block the response of the histamine-storing endocrine cells to gastrin, perhaps because these endocrine cells lack receptors to somatostatin. Conceivably, somatostatin in the gastric mucosa has a paracrine mode of action. The observations of the present study suggest that somatostatin may affect some, but not all of the various cell types in the stomach. Under physiological conditions this selectivity may be achieved in the following ways: 1) Communication may be based on direct cell-to-cell contact. 2) Only certain cell types are supplied with somatostatin receptors.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 71
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 186 (1978), S. 399-412 
    ISSN: 1432-0878
    Schlagwort(e): Pituitary gland ; Dog ; Pars distalis ; Thyrotropin (TSH) ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Using the immunoperoxidase technique and antisera to the specific beta (β) subunits of bovine and rat TSH1, selective immunocytochemical staining was localized in a specific cell population in the pars distalis of the dog pituitary gland. These TSH cells were found to be positive to aldehyde fuchsin, alcian blue, periodic acid-Schiff (PAS) and aniline blue. With the performic acidalcian blue (pH 0.2) -PAS-orange G procedure these cells stained blue-purple, demonstrating FSH/LH cells (blue or turquoise), ACTH/MSH cells (redpurple) and PRL cells (orange-red). The TSH cells were further differentiated from other functional cell types of the pars distalis on the basis of their typical cytological features, intraglandular distribution and by immunocytochemical double staining. In the pars distalis of adult male dogs the TSH cells were mostly shown to be smaller in size and less numerous than in bitches in the anestrous phase of the sexual cycle. Moreover, cytological alterations in the immunoreactive thyrotrophs in the pituitary of male and female dogs generally paralleled the spontaneous changes in thyroid function associated with thyroid atrophy and/or pituitary insufficiency, and thyroid hyperplasia or goiter. In conclusion, because of their specificity and high potency, the antisera to the β-subunits of bovine and rat TSH represent an effective tool for the selective immunocytochemical localization of TSH in the dog pituitary. This allows the study of the morphology and function of TSH cells under different physiological, pathological and experimental conditions.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 72
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 187 (1978), S. 525-534 
    ISSN: 1432-0878
    Schlagwort(e): Salivary glands ; Insects ; Innervation ; Light microscopy ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The innervation of the salivary gland of the cockroach Nauphoeta cinerea (Olivier) has been investigated with the use of light and scanning electron microscopy. Light microscopy of methylene blue stained glands reveals the presence of a dual innervation arising from the ventral nerve cord and the stomodeal nervous system; the principal innervation is that from the ventral nerve cord which passes to the gland via the reservoir ducts. Branches of these nerves form a plexus on the acinar surface, the axons of which exhibit swelling at irregular intervals. The presence of this surface plexus and the axonal swellings was confirmed by scanning electron microscopy both in normal glands and in those in which the basal lamina had been removed by means of an HCl-collagenase digestion method. No acinar plexus was seen to be formed by branches of the stomatogastric nerve that were associated with the gland. However, other branches of this nerve were clearly connected with a complex network of multipolar neurones on the surfaces of the anterior regions of both salivary reservoirs.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 73
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 188 (1978), S. 99-106 
    ISSN: 1432-0878
    Schlagwort(e): LHRH-neurosecretion ; Avian hypothalamus ; Vasotocin neurosecretion ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary A fluorescent technique applying specific LHRH and vasotocin antisera was used for the immunocytochemical localization of the respective neurosecretory systems in the hypothalamus of gonadectomized, testosteronetreated and/or serotonin injected male domestic ducks. An immunoreactive (IR) LHRH-producing system, with perikarya located in the preoptic nucleus, could be traced through the ventral hypothalamus down to the external layer of the rostral and caudal ME, in close vicinity to the hypophysial portal system. An IR-vasotocin system originating in the paraventricular and supraoptic nuclei ran through the ventral hypothalamus, but terminated in (i) the external layer of the rostral ME, and (ii) in the posterior lobe of the hypophysis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 74
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 188 (1978), S. 119-132 
    ISSN: 1432-0878
    Schlagwort(e): Neurophysin ; Paraventricular nucleus ; Supraoptic nucleus ; Sheep ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary An antiserum cross-reactive against ovine neurophysins-I-II and -III has been used in conjunction with the immunoperoxidase histochemical procedure to localize the cells of the sheep paraventricular (PVN) and supraoptic nuclei (SON). In order to describe the topographical distribution of the SON and PVN a study was made on the serial sections cut (a) transversely from rostral to caudal positions and (b) sagittally from lateral to medial positions of the hypothalamus. The cells of the SON, when examined in the transverse aspect, extended approximately 1900 μ caudally and when examined in the sagittal plane were contained within a lateral-medial distance of 4830 μ. In each case the SON cells lay adjacent to the optic chiasm. As sections were cut transversely, the cells of the PVN first appeared in a rostral position defined as 0 μ and close to the ventral lining of the third ventricle. This general ventral and ventro-lateral distribution of cells maintained up to a caudal distance of approximately 840 μ. From positions 1260–2310 μ there was a dramatic dorsal shift of the PVN cells which by this time had also extended laterally. The total rostral-caudal distance occupied by the PVN cells was 3150 μ. That the lateral-medial distance occupied by the PVN was small (1050 μ) was determined on examining the magnocellular nuclei in sagittal section.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 75
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 215 (1981), S. 625-633 
    ISSN: 1432-0878
    Schlagwort(e): Teleost ; Pars intermedia ; Immunocytochemistry ; PAP-technique ; MSH ; ACTH ; Endorphin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The pars intermedia of S. mossambicus contains two different endocrine-cell types. The predominant cell type is lead-haematoxyline-positive and assumed to synthesize MSH and related peptides. The second cell type is PAS positive and its function and product(s) are unknown. Staining of light-microscopic and ultrathin sections with antisera against α-MSH, ACTH 1–24 and human β-endorphin revealed that only the lead-haematoxyline-positive cells of the pars intermedia react with these antisera, and that the secretory granules of these cells contain compounds that were immunoreactive to all three antisera. These findings are in line with the hypothesis that α-MSH, ACTH and endorphins are derived from the same precursor molecule. No specific reaction with one of the antisera could be detected in the PAS positive cells.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 76
    ISSN: 1432-0878
    Schlagwort(e): Digestive tract ; Fish ; Gastrin-immunoreactive cells ; Pancreatic polypeptide-immunoreactive cells ; Somatostatin-immunoreactive cells ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Gastrin, pancreatic polypeptide and somatostatin immunoreactive cells in the gut of two fish with stomachs (perch and catfish) and a stomachless fish (carp) were studied by immunocytochemistry. In the gastric mucosa of perch and catfish, cells showing gastrin and somatostatin-like immunoreactivity are found, scattered among the surface mucous cells and mucous neck cells. No pancreatic polypeptide (P.P.) immunoreactive cells are detected in the gastric mucosa. Cells showing gastrin and P.P.-like immunoreactivity are observed in the intestinal mucosa of perch, catfish and carp. In this location no somatostatin immunoreactive cells are found.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 77
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 189 (1978), S. 409-433 
    ISSN: 1432-0878
    Schlagwort(e): Rete testis ; Human ; Histophysiology ; Chordae retis ; Scanning electron microscopy ; Transmission electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The human rete testis was examined with regard to 1) the number and distribution of entrances of seminiferous tubules, 2) the light microscopic topography and 3) details of the passages as revealed by scanning and transmission electron microscopy. In a newborn 1474 entrances were counted, approximately 50 % entering from the right and 50 % from the left of the central long axis. Three major subdivisions of the rete were distinguished and described: a septal (or interlobular) part represented by tubuli recti, a tunical (or mediastinal) part which is a true network of channels, and an extratesticular part characterized by dilatations (up to 3 mm wide) which we have called bullae retis. In SEM, cylindrical strands running from wall to wall in the tunical and extratesticular rete spaces are a prominent feature. We have called these chordae retis. They are covered by epithelium and are 5–40 μm wide and 15 to more than 100 μm long. They contain a peculiar tissue consisting of central myoid cells in a fibroelastic matrix. The smaller chordae are avascular. In the light of these findings the rete is interpreted as a highly complex myoelastic sponge. Its function is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 78
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 191 (1978), S. 539-548 
    ISSN: 1432-0878
    Schlagwort(e): Frog skin ; Respiratory capillaries ; Capillary networks ; Microcorrosion casts ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Microcorrosion casts of blood vessels in the skin of Rana esculenta L. were examined by means of scanning electron microscopy with particular reference to the subepidermal network of respiratory capillaries. Due to the fact that arteries and veins lie in the deeper layers of the stratum spongiosum of the corium, the respiratory vessels form a morphologically homogeneous network. Functionally, however, this network is subdivided into small areas with a centripetal direction of blood flow. The deep capillary net, situated at the base of the stratum compactum of the corium, is not so dense as the respiratory network and does not directly communicate with it. Alveolar glands of the skin have no effect on the distribution of capillaries in the two networks.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 79
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 204 (1979), S. 147-153 
    ISSN: 1432-0878
    Schlagwort(e): Granulocytes ; Lymphocytes ; Monocytes ; Scanning electron microscopy ; Chicken
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Polymorphonuclear leukocytes, e.g., neutrophilic granulocytes, were enriched from heparinized blood by a Ficoll-step-gradient centrifugation procedure. Scanning electron microscopy (SEM) revealed a surface morphology of narrow ridge-like profiles and small ruffles with occasional microprocesses. Mononuclear leukocytes were isolated by centrifugation over a Ficoll-Metrizoat gradient. The lymphocytes showed varying numbers of microvilli of different length, size and shape. B lymphocytes, characterized by their capability of “sheep red blood cell (SRBC)-rosette formation”, displayed a similar surface morphology. Completely smooth lymphocytes, described in the literature as T lymphocytes, could not be detected, although many lymphocytes with few microprocesses were observed. Thus, SEM is not a useful tool for distinguishing between B and T lymphocytes in the peripheral blood of chickens. Monocytes were characterized by prominent membrane-like ruffles, but in some cases they closely resembled granulocytes. An influence of the various separation media on the surface morphology of the isolated cells could not be detected when compared with cells isolated by the buffy-coat method.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 80
    ISSN: 1432-0878
    Schlagwort(e): α- and β-Endorphins ; Met-enkephalin ; Brain ; Immunocytochemistry ; Rana temporaria (Amphibia, Anura)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the brain of Rana temporaria, two distinct systems reactive with α- and β-endorphin antisera, respectively, and with a met-enkephalin antiserum, have been detected immunohistochemically. Neurons reacting with α- and β-endorphin antisera are located (1) in the preoptic nucleus, and (2) in the pars ventralis of the tuber cinereum. Immunoreactive nerve fibres of both groups of perikarya end in the infundibular floor near the capillaries and the preoptico-hypophysial tract. Control reactions have shown that the immunoreactivity is suppressed by the corresponding antigens, but also by β-LPH. In view of these results the immunoreactive systems examined correspond to an α/β-endorphin system or a lipotropinergic system. Neurons reacting with the met-enkephalin antiserum are located in the paraventricular organ. Intense immunofluorescence was observed in the infundibular floor. Controls show that the labelling by met-enkephalin antiserum is exclusively suppressed by met-enkephalin. In the pituitary gland, on the other hand, α- and β-endorphin antisera reveal: 1) the MSH/ACTH-like cells of the pars intermedia and 2) the ACTH-like cells of the pars distalis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 81
    ISSN: 1432-0878
    Schlagwort(e): Key words Estrogen receptor ; Progesterone receptor ; Gonadotropin-releasing hormone ; Preoptic area ; Hypothalamus ; Immunocytochemistry ; Mink (Mustela vison)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract  The distribution of gonadal steroid (estrogen, progesterone) receptors in the brain of the adult female mink was mapped by immunocytochemistry. Using a monoclonal rat antibody raised against human estrogen receptor (ER), the most dense collections of ER-immunoreactive (IR) cells were found in the preoptic/anterior hypothalamic area, the mediobasal hypothalamus (arcuate and ventromedial nuclei), and the limbic nuclei (amygdala, bed nucleus of the stria terminalis, lateral septum). Immunoreactivity was mainly observed in the cell nucleus and a marked heterogeneity of staining appeared from one region to another. A monoclonal mouse antibody raised against rabbit uterine progesterone receptor (PR) was used to identify the PR-IR cells in the preoptic/anterior hypothalamic area and the mediobasal hypothalamus (arcuate and ventromedial nuclei). This study also focused on the relationship between cells containing sex-steroid receptors and gonadotropin-releasing hormone (GnRH) neurons on the same sections of the mink brain using a sequential double-staining immunocytochemistry procedure. Although preoptic and hypothalamic GnRH neurons were frequently in close proximity to perikarya containing ER or PR, they did not themselves possess receptor immunoreactivity. The present study provides neuroanatomical evidence that GnRH cells are not the major direct targets for gonadal steroids and confirms for the first time in mustelids the results previously obtained in other mammalian species.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 82
    ISSN: 1432-0878
    Schlagwort(e): Key words Immunochemistry ; Chromatography ; Immunocytochemistry ; PACAP ; VIP ; CGRP ; NOS ; GRP ; Gastointestinal tract ; Capsaicin ; Denervation ; Rat (Sprague Dawley ; Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract  The expression of pituitary adenylate cyclase activating polypeptide (PACAP) was studied in the gastrointestinal tract (GI-tract) of normal rats using radioimmunoassay, chromatography, immunocytochemistry, and in situ hybridization. PACAP-38, PACAP-27, and PACAP-related peptide were demonstrated in all parts of the GI-tract, PACAP-38 being the predominant form confirmed by chromatography. PACAP-immunoreactive nerve fibers and nerve cell bodies were found in the myenteric ganglia throughout the GI-tract. PACAP-containing nerve cell bodies were also demonstrated in the submucous ganglia of the small and large intestine. The synthesis of PACAP in intrinsic neurons was confirmed by in situ hybridization. Double immunostaining showed that PACAP is present in calcitonin gene-related peptide-containing sensory nerve fibers as well as in vasoactive intestinal polypeptide (VIP)- or VIP/gastrin-releasing peptide (GRP)-containing (intramural) nerve fibers in the upper GI-tract and in anally projecting, intrinsic VIP-and VIP/nitric oxide syntase-containing nerve cell bodies and nerve fibers in the small and large intestine. Neonatal treatment with capsaicin significantly reduced the concentration of PACAP-38 in the esophagus, stomach, and colon. Extrinsic denervation decreased the PACAP-38 concentration in the stomach, while no change was observed in the small intestine. These results indicate that PACAP- immunoreactive nerve fibers in the GI-tract originate from both intrinsic (enteric) and extrinsic (presumably sensory) sources suggesting that PACAP may have diverse gastrointestinal functions.
    Materialart: Digitale Medien
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  • 83
    ISSN: 1432-0878
    Schlagwort(e): Key words: Leu-callatostatins ; Callatostatins ; Allatostatins ; Neuropeptides ; Peptide purification ; Immunocytochemistry ; Myoinhibition ; Codling moth ; Cydia pomonella (Tortricidae: Lepidoptera) (Insecta)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. A neuroendocrine peptide of the Leu-callatostatin family, LPVYNFGL-NH2, has been isolated from tissue extracts of 5th instar larvae of the codling moth, Cydia pomonella (Lepidoptera). It is identical to a peptide previously isolated from the blowfly, Calliphora vomitoria (Diptera). The distribution of this peptide within the tissues of C. pomonella has been mapped by immunocytochemistry using antisera raised against LPVYNFGL-NH2. Midgut endocrine cells contain Leu-callatostatin immunoreactivity, as do several paired Leu-callatostatin neurones in the brain and ventral nerve cord. Within the visceral nervous system, the frontal ganglion contains four Leu-callatostatin neurones. Axons from these cells combine with others originating from neurones in the brain and project within the nervi cardiostomatogastrici to innervate the tissues of the foregut. In particular, the oesophageal valve has a prominent ring of Leu-callatostatin-immunoreactive fibres. The synthetic peptide, LPVYNFGL-NH2, has a potent reversible inhibitory effect in vitro on all visible forms of spontaneous contractile activity of the foregut, including closure of the oesophageal valve. Complete myoinhibition is observed at peptide concentrations from 10−10 to 10−16 M. These results, in conjunction with the results of similar studies on cockroaches, crickets and flies, suggest that the Leu-callatostatins are a ubiquitous family of insect neuroendocrine peptides with an important role in the control of gut motility.
    Materialart: Digitale Medien
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  • 84
    ISSN: 1432-0878
    Schlagwort(e): Key words: Pineal organ ; Pinealocytes ; Pineal photoreceptors ; Sensory structures ; Photopigment ; Pinopsin ; Immunocytochemistry ; Chicken
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Pinopsin is a photoreceptive molecule cloned from the chicken pineal organ. An antibody highly specific for pinopsin was applied in light- and electron-microscopic immunocytochemical studies of the pineal organ of 1 to 2-month-old chickens. Intense immunoreactivity was found in the follicular lumen at the light-microscopic level. In addition, small immunoreactive spherical or fibrous structures were diffusely distributed at the parafollicular aspect of the pineal organ. To identify immunoreactive elements precisely, we used pre-embedding immunoelectron microscopy. These studies revealed immunoreactive outer segments of pinealocytes arranged closely side by side in the follicular lumina. The thin initial portion of the outer segment arose from a basal body located in the inner segment. Immunoreactive pear-shaped outer segments occupied small lumina. Follicular lumina displayed immunonegative arrays of whorl-like lamellar membranes. Occasionally, these immunonegative structures were surrounded by immunoreactive concentric lamellar complexes. In the parafollicular pineal parenchyma, long slender cilium-like structures or enlarged cilia and concentric lamellar arrays showed intense immunoreactivity. All immunoreactive structures observed in this study were considered to represent outer segments of pinealocytes of the chicken pineal organ.
    Materialart: Digitale Medien
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  • 85
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 289 (1997), S. 265-274 
    ISSN: 1432-0878
    Schlagwort(e): Key words: Retina ; Amacrine cells ; Neurotransmitters ; Immunocytochemistry ; Tyrosine hydroxylase ; Dopamine ; Ichthyophis kohtaoensis (Gymnophiona)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Ichthyophis kohtaoensis, a member of the limbless Gymnophiona, has a specialized subterranean burrowing mode of life and a predominantly olfactory-guided orientation. The only visually guided behavior seems to be negative phototaxis. As these animals possess extremely small eyes (only 540 μm in diameter in adults), functional investigations of single retinal cells by electrophysiological methods have so far failed. Therefore, the content and distribution of retinal transmitters have been investigated as indications for a functioning sense organ in an animal that is supposed to be blind. In this study, the organization and development of the dopaminergic system have been examined in the retinae of embryonic, larval, and adult I. kohtaoensis, by using an antiserum against tyrosine hydroxylase, the rate-limiting enzyme in the catecholamine synthetic pathway, and an antiserum against dopamine itself. Labeled somata are situated in the inner nuclear layer and in the ganglion cell layer. Dopamine-positive fibers form a dense diffuse plexus, that covers the whole inner plexiform layer, whereas tyrosine hydroxylase-immunoreactive processes show a tendency to arborize in a stratified manner. Tyrosine-hydroxylase-immunolabeled fibers can occasionally be observed in the optic nerve head of larval stages. During ontogenesis and larval development, the distribution of transmitter-expressing cells changes and their number decreases, but no general degeneration of the visual system is detectable. Adult Ichthyophis still have retinal transmitters, indicating that the eyes, although obviously playing a minor role in a subterranean ecological niche, retain all the elements of functioning sense organs.
    Materialart: Digitale Medien
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  • 86
    ISSN: 1432-0878
    Schlagwort(e): Key words: Intracardiac neurones ; Innervation ; Heart ; Neuropeptide Y ; Immunocytochemistry ; Electron microscopy ; Rat (Sprague Dawley) ; Guinea-pig (Dunkin Hartley)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Intrinsic neuropeptide Y-containing neurones in rat and guinea-pig hearts were studied at the ultrastructural level by the pre-embedding peroxidase-antiperoxidase immunocytochemical technique. Intracardiac neuronal cell bodies were often weakly or moderately immunostained, and the labelling was usually pronounced in the Golgi complex, multivesicular bodies, some cisterns of granular endoplasmic reticulum and large granular vesicles. Neuropeptide Y-immunoreactive nerve fibres were also observed in association with intracardiac neurones. A subpopulation of neuropeptide Y-immunoreactive granule-containing cells in the rat heart are described for the first time and were very heavily labelled; other granule-containing cells were non-immunoreactive, but were contacted by neuropeptide Y-containing nerves. Preterminal regions of nerve fibres that were located in nerve bundles were only weakly neuropeptide Y-immunoreactive, in contrast to the heavy labelling observed in varicosities that contained many synaptic vesicles. Many neuropeptide Y-immunoreactive nerve fibres were associated with the coronary vasculature and were particularly prominent in the walls of small arteries and arterioles where labelled nerve varicosities were present close to the smooth muscle cells. Immunoreactive nerves were also seen in the myocardium, usually near to capillaries. In axonal varicosities, the central core of large granular vesicles was immunolabelled, and electron-dense immunoreactive material outlined the membranes of small and large clear vesicles. The significance of neuropeptide Y-immunoreactive intracardiac neurones and granule-containing cells and the origin of associated labelled nerve fibres in the heart are discussed.
    Materialart: Digitale Medien
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  • 87
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 201 (1979), S. 315-325 
    ISSN: 1432-0878
    Schlagwort(e): Immunocytochemistry ; Post-natal development ; Neurohypophysial peptides ; Magnocellular and parvocellular neurons
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Immunocytochemical localization of vasopressin (VP), oxytocin (OXY) and neurophysins I and II (NI and NII) in the hypothalamus of growing rats revealed several new features. Hormones and neurophysins were present in magnocellular neurons of newborn rats: VP and NII in a first neuronal population, OXY and NI in a second neuronal population. For the first three days after birth, the ratio of detected VP to detected NII increased whereas the ratio of detected OXY to detected NI appeared constant. It was obvious that maturation of the OXY/NI magnocellular system occurred later than maturation of the VP/NII magnocellular system. During the first three weeks of development, VP/NII fibres in the median eminence were separated into two distinct groups: the hypothalamo-neurohypophysial tract in the internal part of the median eminence, and pericapillary endings heavily loaded with VP and NII in the external part of median eminence. OXY/NI fibres did not show this particular distribution. Therefore, during this post-natal period, loading of infundibular VP endings was related to the increase of ACTH synthesis demonstrated by various authors. Therefore, we suppose that simultaneous participation of VP and corticotropin-releasing hormone does not only appear during experimental and chronic stimulation of ACTH synthesis (after adrenalectomy, for example) but that it also exists during physiological stimulation of corticotropic function. At birth, parvocellular suprachiasmatic neurons were devoid of VP and NIL A slight immunological reactivity appeared in 6-to 10-day-old rats and it became equivalent to the immunological staining in the adult rat during the third post-natal week. Thus, the appearance of suprachiasmatic VP preceded the differentiation of the rhythmic activity of the pituitary adrenal axis. These chronological relationships suggest the involvement of the suprachiasmatic VP-related-peptide in the circadian periodicity of the corticotropic function.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 88
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 201 (1979), S. 349-359 
    ISSN: 1432-0878
    Schlagwort(e): Hypothalamus ; Rat ; Somatostatin-containing neurons ; Immunocytochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The rat hypothalamus was studied at the light microscopic level with the use of single and double immunocytochemical staining methods. It was shown that the rat supraoptic and paraventricular hypothalamic nuclei, and their accessory neurosecretory nuclei, do not contain magnocellular somatostatin neurons. The distribution of the hypothalamic parvocellular somatostatin cells is described. The parvocellular component of the rat hypothalamic paraventricular nucleus is, at least partly, composed of somatostatin cells: they form a fairly well circumscribed periventricular cell mass. The rat suprachiasmatic nuclei contain separate somatostatin neurons and vasopressin neurons. Scattered somatostatin cells are present in the entire arcuate nucleus. In addition to the periventricular somatostatin cells located in the preopticanterior hypothalamic area and in the arcuate nucleus, the rat hypothalamus also contains numerous scattered somatostatin cells located distant from the third ventricle.
    Materialart: Digitale Medien
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  • 89
    ISSN: 1432-0878
    Schlagwort(e): Immunocytochemistry ; Vasopressin ; Oxytocin ; Somatostatin ; Luteining hormone releasing hormone
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The hypothalamic hormones arginine-vasopressin (AVP), oxytocin (OXT), somatostatin (SOM), and luteinizing hormone-releasing hormone (LHRH) were localized in the rat neurohypophysis by the use of semithin serial sections and the unlabeled antibody enzyme method. Clusters of AVP fibres are present within the central region of the neural lobe, clusters of OXT fibres mainly in the peripheral part. The AVP fibres enter bilaterally into the neural lobe. The results call into question previous reports on the presence of AVP on receptors in the pars intermedia cells, since incubation with anti-AVP resulted in similar staining in the pars intermedia of the Wistar and homozygous Brattleboro rat, a mutant strain deficient in AVP. The same intermediate lobe cells are stained after incubation of serial sections with anti-AVP and anti-α-melanocyte-stimulating hormone (α-MSH). This staining of anti-AVP could be removed by solid phase absorption to α-MSH and is thus most probably due to cross reaction with α-MSH. SOM fibres appear to be present in the peripheral parts of the proximal neurohypophysial stalk and mainly lateral in its more distal parts. In the neural lobe they rapidly decrease in number, although some fibres continue into the distal part of the neural lobe, running bilaterally and situated adjacent to the pars intermedia. The SOM staining within magnocellular elements, which has been reported in the literature, can most probably be explained by cross reaction of anti-SOM with neurophysins. LHRH fibres are very scarce in the neurohypophysial stalk and absent in the neural lobe.
    Materialart: Digitale Medien
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  • 90
    ISSN: 1432-0878
    Schlagwort(e): Immunocytochemistry ; ACTH ; Lymnaea stagnalis ; Neurohormone ; Neurotransmitter
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Two giant neurons (diameter 130 μm) were identified immunocytochemically by means of the unlabeled antibody enzyme technique with anti ACTH 1–39 and 1–24 in the pond snail Lymnaea stagnalis. The cells are located in the visceral and the right parietal ganglion, respectively. They contain moderately electron dense elementary granules (diameter 150–160 nm). By means of the intracellular horseradish peroxidase injection technique it was shown that the cells send fibres into the neuropiles of various ganglia and into nerves. Synapses occur on the fine fibre branches in the neuropile. Synapse-like structures were found on the cell bodies and on the major fibres. The giant neurons are electrotonically coupled. With toluidine blue staining for small peptides it was demonstrated that in the central nervous system of the pond snail numerous peptidergic neurons occur in addition to those identified with the classical staining methods for neurosecretion.
    Materialart: Digitale Medien
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  • 91
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 187 (1978), S. 105-113 
    ISSN: 1432-0878
    Schlagwort(e): Mesonephros ; Lamprey ; Renal corpuscle ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The renal corpuscle of the lamprey mesonephros was studied under the scanning electron microscope. Bowman's capsules with individual spaces are chockshaped sacs closely packed together along a medial artery. The lateral walls of the capsules are apposed to those of neighbouring capsules. Glomerular capillaries from the medial artery extend radially between the apposed walls of neighbouring Bowman's capsules. Bulgings of capillaries into the capsular space are associated with mesangial folds of the capsular epithelium. The transitional zone of the visceral layer with podocytes and the parietal layer of squamous epithelium is bounded by linearly arranged rod-shaped epithelial cells. Apertures of the urinary tubule are lined by cells equipped with a fascicle of cilia.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 92
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 188 (1978), S. 375-388 
    ISSN: 1432-0878
    Schlagwort(e): Urinary bladder ; Skin ; Toad, frog ; Water flow ; Na transport ; Vasopressin ; Cytochalasin B ; Microfilaments ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary A morpho-functional study of the effects of cytochalasin B (CB) on Na and water transport was made in amphibian epithelia. The functional studies confirmed the dissociation of the natriferic and hydrosmotic effects of vasopressin in toad urinary bladders exposed to CB and showed in addition that the block of the hydrosmotic effect was reversible and could still be induced in epithelia maximally stimulated with the hormone. Scanning electron microscopy revealed that CB, per se, did not alter the apical surface of the bladders. An almost total loss of microvilli of granular cells was seen, however, if CB was associated with vasopressin and an osmotic gradient. The results suggest two points: a) the block of the hydrosmotic flow induced by CB is due to factors beyond the apical membrane; b) microfilaments may be important mechanochemical transducers in the chain of events leading to the hydrosmotic effect of vasopressin.
    Materialart: Digitale Medien
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  • 93
    ISSN: 1432-0878
    Schlagwort(e): Immunocytochemistry ; Biologically active peptides ; Lymnaea stagnalis ; Neurohormone ; Neurotransmitter
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Perikarya and nerve fibers were immunocytochemically identified in the central nervous system of the pond snail Lymnaea stagnalis by means of the unlabelled antibody enzyme method with antisera to 15 biologically active peptides of vertebrates: vasopressin, vasotocin, oxytocin, α-melanocyte stimulating hormone (α-MSH), met-enkephalin, somatostatin, glucagon, insulin, glucose-dependent insulinotropic peptide (GIP), vaso-active intestinal polypeptide (VIP), gastrin, secretin, pancreatic polypeptide (PP), Substance P, calcitonin. No immunostaining was obtained with antisera to β-endorphin, cholecystokinin (CCK), neurophysin I and II. Particular neurons could be identified with two antisera (anti-vasopressin/vasotocin, anti-α-MSH/metenkephalin, anti-substance P/PP, anti-PP/gastrin). Apparently this indicates that populations of cells identified with a given antiserum may consist of more than one cell type. Only a few of the new peptidergic cells appeared to be identical with classical neurosecretory cells. Thus the growth hormone producing Light Green Cells stained with anti-somatostatin and the axon terminals of the ovulation hormone producing Caudo-Dorsal Cells with anti-met-enkephalin. Whether this indicates structural identity of the growth hormone with somatostatin and of the ovulation hormone with met-enkephalin remains to be investigated. Just like the classical neurosecretory cells a number of the new peptidergic cells (anti-glucagon, -insulin, -met-enkephalin, -somatostatin, and -PP positive cells) send their axons to the peripheries of commissures, connectives or nerves. Thus these cells can be considered as probably neuroendocrine. The classical neurosecretory cells release their products into the haemolymph from these sites. Other new peptidergic cells (e.g., anti-vasopressin, -vasotocin, -oxytocin and -GIP positive cells) have axons that terminate, probably synaptically, on other neurons, indicating that they are “more conventional” neurons, their products being neurotransmitters/neuromodulators. It can also not be excluded that some cells of a population containing a given peptide are neuroendocrine and others make contact with other neurons.
    Materialart: Digitale Medien
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  • 94
    ISSN: 1432-0878
    Schlagwort(e): Key words: Quinolinic acid ; Interferon-γ ; Kynurenine ; Electron microscopy ; Immunocytochemistry ; Excitotoxicity ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract.  Quinolinate (QUIN), a tryptophan-derived excitotoxin, was localized ultrastructurally in human peripheral blood monocytes/macrophages (MØ) by immuno-electron microscopy. A combined carbodiimide/glutaraldehyde/paraformaldehyde-based fixation procedure was developed for optimal retention of QUIN in the cell as well as minimal loss of ultrastructure; a silver-enhanced colloidal gold detection system was used for electron-microscopic analysis. Gold particles representing QUIN immunoreactivity were associated with the inner side of the plasma membrane in normal MØ. The number of gold particles increased significantly when QUIN levels were elevated by treatment with its precursor kynurenine, but location of the gold particles remained essentially the same under this condition. Treatment with interferon-γ increased the number of Golgi bodies, vacuoles and pseudopodia, reflecting the activated state of the cell. Significantly increased numbers of gold particles representing QUIN were detectable in approximately the same location as in the case of kynurenine treatment. Combined treatment with kynurenine and interferon-γ maximally increased the number of gold particles at the periphery of the cell. The pseudopodia were intensely stained with gold particles, while they were not detectable in the inner part of the cytoplasm or in any other organelle even under this activated condition. The significance of the specific location of QUIN revealed in the present study and its relation to the release and subsequent actions of QUIN are discussed.
    Materialart: Digitale Medien
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  • 95
    ISSN: 1432-0878
    Schlagwort(e): Key words: Urothelium ; Tartrate-resistant acid phosphatase ; Nitric oxide synthase I ; Superoxide dismutase ; Immunocytochemistry ; Free radicals ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Three enzymes, viz., tartrate-resistant acid phosphatase (TRAP), nitric oxide synthase I (NOS-I), and superoxide dismutase (SOD), involved in the production and metabolism of free radicals or radical equivalents, were demonstrated by immunocytochemistry in the urothelium of the ureters of six patients of various ages. Two of these enzymes (TRAP and NOS-I) were colocalized in the most apical and lateral border of the superficial cells of the urothelium. In contrast, SOD showed a patchy or granular distribution within the supranuclear region of these cells. Intra- and subepithelial macrophages exhibited a weak TRAP, but no NOS-I or SOD, immune reaction. On the basis of the immunocytochemical findings, arguments in favor of a cytotoxic function of the superficial cells of the human urothelium are presented.
    Materialart: Digitale Medien
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  • 96
    ISSN: 1432-0878
    Schlagwort(e): Key words: Oxytocin ; Immunocytochemistry ; Paraventricular nucleus ; Superior cervical ganglion ; Spinal cord ; Sympathetic nervous system ; Retrograde tracing ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. The paraventricular nucleus of the hypothalamus is a major integrative nucleus for relaying information from the suprachiasmatic nucleus to the autonomic system. The precise pathway by which this information can influence autonomic functions, such as melatonin synthesis in the pineal gland, is not clear. In the present study, we used a retrograde tracer injected in the superior cervical ganglion to identify spinal preganglionic neurons. One of the main neurotransmitters present in descending projections of the paraventricular nucleus of the hypothalamus, oxytocin, was detected with immunocytochemistry to visualise possible contacts with the neurons located in the intermediolateral column of the spinal cord and projecting to the superior cervical ganglion. Although many appositions could be seen at the light-microscopic level, this abundance could not be confirmed at the electron-microscopic level. The implications of these observations for the overall timing message received by the spinal preganglionic neurons are discussed.
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  • 97
    ISSN: 1432-0878
    Schlagwort(e): Key words: Crustacean hyperglycaemic hormone ; Immunocytochemistry ; Neurohaemal organ ; Daphnia magna ; Artemia salina (Crustacea)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Crustacean hyperglycaemic hormone-immunoreactive neuronal systems are detected in the central and peripheral nervous systems of two entomostracan crustaceans, Daphnia magna and Artemia salina, by immunocytochemistry using specific antisera against crustacean hyperglycaemic hormones of the decapod crustaceans Orconectes limosus and Carcinus maenas. In D. magna, four small putative interneurones are detected in the brain. In the thorax, ten bipolar peripheral neurones are stained by both antisera. They are obviously segmental homologues with centrally projecting axons that form interdigitating varicose fibres and terminals in putative neurohaemal areas next to the surface of the anterior part of the thoracic ganglia. Similar immunopositive neurones occur both in the central and peripheral nervous systems of A. salina. A total of five groups of neurones occur in the protocerebrum, the deutocerebrum and the mandibular ganglion. Some of the protocerebral neurones are bipolar and project to the dorsal frontal organ. A single pair of peripheral multipolar neurones in the maxillary segment projects centrally into the ventral nerve cord and innervates unidentified somatic muscles and tissues in the maxillary and the first appendage segments. None of the brain neurones in both species show similarities to decapod X-organ sinus gland neurosecretory neurones. Chromatography of brain extracts of D. magna combined with immunodot blotting revealed two strongly immunoreactive fractions at retention times close to that of the crustacean hyperglycaemic hormone of crayfish. Moreover, preabsorption controls suggest that the cross-reacting peptides of D. magna and A. salina are structurally closely related to those of decapods.
    Materialart: Digitale Medien
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  • 98
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 290 (1997), S. 119-128 
    ISSN: 1432-0878
    Schlagwort(e): Key words: Allatostatin ; Immunocytochemistry ; In situ hybridization ; Hemocytes ; Inhibition of corpora allata ; Diploptera punctata (Insecta)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Allatostatins are neuropeptides that inhibit the production, by the corpora allata, of a major insect hormone, juvenile hormone. These peptides are produced by cells of the brain and ganglia as well as by midgut endocrine cells. Transport from these sites may contribute to the allatostatin content in the hemolymph (insect blood). Using a monoclonal antibody against Diploptera punctata allatostatin I (A-P-S-G-A-Q-R-L-Y-G-F-G-L-NH2) and in situ hybridization with a digoxigenin-labeled cRNA probe generated from a portion of the allatostatin gene, it is demonstrated that allatostatin is present in and synthesized by granular hemocytes of D. punctata. About 5% of the hemocytes react with anti-allatostatin antibody and a similar number hybridize with a cRNA probe that detects allatostatin-specific mRNA. Electron micrographs showed that allatostatin-immunoreactive material occurs in membrane-bound, uniformly dense granules that frequently fill fusiform-shaped cells. Allatostatin in cell and plasma fractions of hemolymph quantified by enzyme-linked immunosorbent assay and by bioassay for inhibition of juvenile hormone synthesis in vitro indicated that about equal quantities (0.1–0.2 fmol/μl) are present in cell and plasma fractions. The production of allatostatin by hemocytes suggests that allatostatins may function as regulatory peptides in hemolymph activities in addition to their other known functions.
    Materialart: Digitale Medien
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  • 99
    ISSN: 1432-0878
    Schlagwort(e): Key words: Aquaporins ; AQPcic ; Filter chamber ; Homopteran insects ; Immunocytochemistry ; Cicadella viridis ; Euscelidius variegatus ; Scaphoideus titanus (Insecta)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. In the Homopteran order of insects, the plant xylem feeders exhibit a highly differentiated part of their digestive tract known as the filter chamber. In this tissue, water crosses plasma membranes through a transepithelial osmotic gradient. In previous studies on the filter chamber of Cicadella viridis, we purified and characterized from the plasma membranes a 25 kDa protein that we demonstrated to be an aquaporin (or water channel, member of the major intrinsic protein family, a group of membrane channels for small solutes). We called this protein AQPcic for Cicadella aquaporin. In the present study, we used polyclonal antibody anti-AQPcic in Western blotting and immunocytochemical analysis of the intestinal tract of Cercopis sanguinolenta, Philaenus spumarius, Aphrophora alni (Cercopidae), Euscelidius variegatus, and Scaphoideus titanus (Jassidae). Western blotting experiments revealed that immunologically related AQPcic proteins are found in those species. The molecular weight of these proteins is 15–26 kDa. Immunocytochemical studies on ultrathin filter-chamber sections revealed that the anti-AQPcic antibody systematically labelled the membrane microvilli of epithelial cells. A good correlation thus exists between the physiology of these cells and the presence of aquaporin-related proteins in their membranes.
    Materialart: Digitale Medien
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  • 100
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 199 (1979), S. 349-352 
    ISSN: 1432-0878
    Schlagwort(e): Spermatozoa ; Mitochondria ; Scanning electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary As seen by scanning electron microscopy, the mitochondrial helix in the developing midpiece of mouse testicular spermatozoa is dextral in direction and consists of spherical mitochondrial units arranged in an orderly array of four units per gyre: three appearing in face view and a fourth hidden from view at the back of the gyre. As the spermatozoa mature, the dextral helix is transformed into a sinistral helix. Its constituent spherical mitochondria either change direction abruptly without changing shape; or having first become semilunar or diamond-shaped, they change direction gradually. Mitochondrial division follows the change in helical pitch producing a double sinistral helix. The spherical (or semilunar/diamond-shaped) mitochondria presumably elongate to form the units of the mature midpiece.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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