A transmission and scanning electron microscope study of primary neural induction

Summary Normal primary neural induction has been further studied by TEM and SEM. A single mesoderm cell is usually in contact with several ectoderm cells. The mesoderm cells are also contacting other mesoderm cells. It is suggested that ectoderm cells are induced in groups and that induction is synchronized by these contacts. At the points of contact between mesoderm and ectoderm cells cytoplasmic changes are present in the induced tissue.Acknowledgments. M. A. E. would like to thank Prof.F. Beck in whose department this work was conducted. An especial acknowledgment to Mr.Jeff Smith for technical assistance.S. V. C. would like to thank Prof.R. P. Dale in whose department the SEM photographs were prepared.     

Primary neural induction as studied by scanning electron microscopy.

Normal primary neural induction has been studied by scanning electron microscopy and the results compared with those obtained by TEM. Mesoderm cells are usually in contact with several other cells, both mesodermal and endodermal in origin. By SEM the ectoderm layer has been shown to be in contact with the underlying mesoderm cells. Tufts of fibrous basement membrane are also present between the two cell types. TEM specimens also show an intermediate basement membrane.     

Quantitative ultrastructural differences in the mitochondrium of pleomorphic bloodforms ofTrypanosoma brucei

Zusammenfassung Morphometrisch wird gezeigt, dass die stumpfe Blutform («stumpy form») vonTrypanosoma brucei ein grösseres Mitochondrium besitzt als die schlanke Form («slender form»). Die strukturelle Zusammensetzung des Mitochondriums bleibt annähernd gleich.

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This work has partly been supported by the Schweizerischer Nationalfonds zur Förderung der wissenschaftlichen Forschung.

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The authors wish to thank ProfessorE. R. Weibel for his interest in this work. We also thank MissS. Bleiker and MrK. Babl for their skillful technical assistance.     

Thymus,peripheral lymphoid tissues and immunological responsiveness of the pituitary dwarf mouse

Riassunto L'autore ha studiato la morfologia del sistema linforeticolare e lo stato di reattività immunitaria del topo Snell/Bagg con nanismo ereditario preipofisario. È stata riscontrata una notevole ipoplasia di tutto il sistema linforeticolare ed una severa diminuzione della capacità anticorpopoietica la cui causa viene fatta risalire con ogni probabilità al grave stato di deficit timico congenito. Si prospetta che il topo nano ipofisario sia portatore di una sindrome analoga a quella sperimentalmente indotta mediante timectomia neonatale.

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The author wishes to thank ProfessorCesare Cavallero and ProfessorMarco Fraccaro for their suggestions and criticism. The technical assistance of MissL. Forni and Mr.G. P. Tonda of the Cattedra di Immunologia of the University of Milan is also greatly appreciated.     

Testing of rifampicin on possible genetic effects onDrosophila melanogaster and human leukocyte chromosomes in vitro

Zusammenfassung Mutagenitätsuntersuchungen von Rifampicin anDrosophila melanogas (X-chromosomale rezessive Letalmutationen) und an menschlichen Leukozytenchromosomen in vitro ergaben keine Anhaltspunkte für eine genetische Wirksamkeit dieser Substanz.

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We thank Mrs.R. Pieper for her carful technical assistance. We are also grateful to ProfessorR. Hess and Dr.J. Gelzer (Ciba-Geigy, Basel) for the supply of rifampicin.     

Degeneration of noradrenergic nerve terminals in submucous ganglia of the rat duodenum following treatment with 6-hydroxydopamine

Zusammenfassung Nachweis adrenerger Synapsen an Zellkörpern der duodenalen submukösen Ganglien von Ratten nach 6-Hydroxydopamin-Behandlung.

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Part of this work was done while I was on sabbatical leave in the Department of Anatomy, Monash University, in 1972, and I thank ProfessorG. C. Schofield for his kindness and encouragement during my stay there. Mr.H. L. Chan rendered invaluable technical assistance.     

The prinary tissue culture of rat adult decapsulated adrenal glands: Problems of methodology and applications

Riassunto Le colture primarie di surrene di Ratto adulto si prestano molto bene a studi morfologici e funzionali mediante tecniche di indagine diverse (microscopia ottica ed elettronica, istochimica, autoradiografia, biochimica). Sono stati effettuati studi originali sulla coltura di tessuto surrenale dopo permanenza prolungata in azoto liquido e sull'isolamento di linee cellulari differenziate di cellule corticali.

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Acknowledgment. Authors thank ProfessorV. Meneghelli, Director of this Institute, for his encouragement and interest in this work. MissLucia Bolognani and Dr.Anna Belloni provided skilful technical assistance.     

Occurence of diploid drones in a neotropical bumblebee

Zusammenfassung Mutter-Sohn-Kreuzung bei der südamerikanischen HummelBombus atratus Franklin ergab diploide Männchen mit normalen Arbeiterinnen im Verhältnis von 3 zu 1. Tur Interpretation des genetischen Mechanismus wurden 2 geschlechtsgebundene Loci angenommen, als bisher angenommen wurde, was für einen älteren Mechanismus bei Apiden spricht.

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This study was made possible by a grant of the State of São Paulo Research Foundation (FAPESP).

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Acknowledgment. I would like to thank Dr.W. E. Kerr, Dr.R. Zucchi and Dr.S. F. Sakagami for their excellent assistance during the course of this investigation as well during the translation. I also would like to thank Dr.R. H. Crozier for his suggestions and comments and I extend my thankfulness to professorsJ. Chaud Netto andZ. Silveira.     

A modified dipeptide from the algaCystoseira corniculata hauck

Summary A modifiedl-Phe-l-Phe dipeptide has been isolated from the algaCystoseira corniculata.We thank ProfessorK. C. Güven, Botanical Institute, University of Istanbul, for collecting the alga.     

Transplantation of an entire muscle in mice

Zusammenfassung Bei Mäusegeschwistern führte homoplastische Transplantation kleiner Muskeln in toto zur Wiedererlangung ihrer vollen Funktion unter nervöser Kontrolle.

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We thank ProfessorM. Otsuka, Dr.H. Ishikawa and Dr.E. Ozawa for their helpful suggestions and discussions and ProfessorM. Kuno for his review on this paper. We are also indebted to the Central Institute for Experimental Animals (Tokyo) for providing the mice.     

The effect of selective cardiac adrenergicβ-blockade on the hypotensive effect of hydrallazine

Zusammenfassung Es wird gezeigt, dass Verabreichung von Hydrallazin einen Blutdruckabfall und eine reflektorische Tachykardie zur Folge hat. Nach Praktololgabe wird eine Hemmung der reflektorischen Tachykardie erreicht, während die blutdrucksenkende Wirkung erheblich vermindert wird.

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Acknowledgments. We would like to thank MissMargaret Budden for technical assistance.     

Relation between the glycogen content of the liver and liver weight,and its meaning for enzymology

Zusammenfassung Schwankungen des Glykogengehalts verursachen sehr schnelle Veränderungen des Lebergewichtes und daher auch solche des prozentualne Proteingehalts der Leber. Enzymaktivität sollte deshalb pro Körpergewicht und nicht pro Lebergewicht ausgedrückt werden, wie dies oft geschieht.

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Acknowledgments. The authors wish to express their gratitude ProfessorA. de Minjer for his support, to ProfessorL. W. J. Holleman, ProfessorJ. W. Koten and ProfessorH. Schimassek for helpful suggestions and to Mrs.L. C. Freelink-vander Velden for technical assistance.     

Differential effects of lipids on the osmotic fragility of lysosomes

Summary The effect of a wide range of concentrations of oleic acid, oleyl alcohol and oleic acid methyl ester on lysosomal stability has been studied under both hypotonic and isoosmotic medium conditions. Both oleic acid and oleyl alcohol exhibited a biphasic interaction pattern with lysosomes; stabilizing at low concentrations and labilizing at high concentrations. Lysosome labilization by the ester required an initial lag period.Acknowledgment. We should like to thank Mr.David Ginzburg for the assistance he gave us during the 3 months he spent at our department as a summer student.     

Induction of chromosome abnormalities by reversal of colcemid inhibition in leucocyte cultures

Zusammenfassung Menschliche Leukozyten, die vorher 2 resp. 4 h der Wirkung von Colcemid ausgesetzt worden waren, ergaben in Zellkulturen 45 resp. über 50% Zellen mit 45 oder weniger Chromosomen im Vergleich zu 10% in Kontrollkulturen ohne Colcemid.

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This work is supported financially by Schering Chemicals Ltd., Burgess Hill, Sussex. We would like to thank Dr.A. G. Pitchford for advice and MissE. Gristwood for technical assistance.     

The deposition of ingested silver in the rat kidney at different ages

Résumé Si l'cau potable est additionnée de 0,15% de nitrate d'argent, l'argent se dépose dans les reins des rats immatures plus lentement et en moins grande quantité que chez les adultes, et ces granules sont partout plus petits. Il est probable que ces résultats indiquent un abaissement de la perméabilité des capillaires chez les immatures.

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The technical assistance of Mrs.Beverley Thomas and MissLucia Maw is gratefully acknowledged. This work was supported by a grant from the Medical Research Council. The electron microscope is on permanent loan from the Wellcome Trust to ProfessorJ. D. Lever, whom we thank.     

Frequency of the various stages of the seminiferous epithelium in different strains of male mice

Summary The duration of the various development stages of the seminiferous epithelium in different strains of male mice was determined by scoring the frequency distribution in randomly selected tubule cross-sections. The results obtained show a difference in the duration of the various stages between the different strains.Acknowledgments. The authors would like to thank Dr.J. Baarli and many other members of the Health Physics Group for their help and valuable assistance during the process of this work.     

Reflexine,a new indole alkaloid ofRauwolfia reflexa

Summary Reflexine, a new indole alkaloid, has been isolated from the leaves ofRauwolfia reflexa Teijsm. and Binn. From spectral studies, chemical reactions and correlation with seredamine, reflexine is shown to be its C-17 epimer (IV).Grateful thanks are accorded to ProfessorR. H. Thomson, Dr.R. T. Brown, Dr.Nitya Nand and Dr.S. C. Pakrashi for spectral measurements. Financial assistance from CCRIMH, New Delhi, and UGC, New Delhi, are also thankfully acknowledged.     

Protein renewall in the photoreceptor outer segments of the pigeon retina

Résumé Les segments externes des bâtonnets de la rétine du pigeon sont totalement renouvelés en 3–4 jours. La distinction fondamentale entre les méchanismes de renouvellement des protéines discales des bâtonnets et des cônes a éte retrouvée dans cette espèce.

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Supported by Grant No. 3287-67 from the Swiss National Found for Scientific Research.

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We thank ProfessorP. G. Waser for support and MissM. Hofmann and Mrs.E. Hofmann for technical assistance.     

Visualisation of lectin binding sites on the surface of human platelets using lectins adsorbed to gold granules

Summary Washed human platelets have been incubated with the lectins WGA, ConA and RCA₁, adsorbed to differentsized gold particles. Plasma membrane receptors for each lectin were then located by scanning and transmission electron microscopy.Acknowledgments. We would like to thank Mlle Dominique Dupuis for technical assistance. This work was supported in part by grant No. CRL 78.5.128.1 from INSERM.     

The distribution of bilirubin in rat liver fractions

Zusammenfassung Die Bilirubinmengen in den Geweben ikterischerGunn-Ratten werden zusammen mit den in den subzellulären Anterilen vorliegenden Bilirubinmengen ikterischerGunn-Rattenlebern bestimmt. Die Bilirubinbestimmung erfolgte nach i.v. Infusion von Bilirubin in die Rattenleber: es findet sich vorwiegend im Leberzellensaft der ikterischenGunn-Ratte, verteilt sich jedoch nach Bilirubininfusion gleichmässig über alle Leberanteile. Die teils bekannten, teils bestätigten Unterschiede können durch Plasma-Eiweiss-Bindung des Bilirubins erklärt werden.

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We would like to thank Professor N. H.Martin for his advice and encouragement and the British Empire Cancer Campaign for financial assistance.