X-ray microanalysis of animal tissues by means of the field emission-scanning electron microscope

Summary With FESEM the X-ray microanalysis of unstained ultrathin sections (600 Å) free of osmium is possible. Deposits in smooth muscle cells of arteriosclerotic aortae show high calcium-peaks already after 80 sec of measurement. No contamination spots were seen after 11 min of measurement on the same point.     

Secretory phenomenon of the adenohypophyseal cells viewed with the scanning electron microscope

Summary Exocytosis from rat adenohypophyseal cells, probably somatotrophic, was studied in the scanning electron microscope after freeze fracturation of the glands. This technique permitted the distinguishing of a clearly delimited exoplasm interrupted by the passage of the secretory granules. It was postulated that the exoplasm could be involved in the control of the release of secretory granules in the endocrine cells studied. At the basal cell surface a simultaneous discharge of several secretory granules has been detected.With the technical assistance of Mr P.-A. Milliquet.     

Characteristics of the nucleolini observed under the electron microscope

Summary Observations with the electron microscope permitted us to ascertain that in molluscs and echinoderms oocytes and in malignat tumour cells, the nucleolini, already seen with the phonton microscope, correspond to the clear fibrillar zones. These present fibrils 40–60 Å thick, spread throughout a very clear matrix. All around these zones there are other closely thickened and interlacing fibrils.     

A new small molecular tracer for permeability studies with the electron microscope

Résumé Le gluconate de fer a la propriété de suivre les molécules d'un poids moléculaire de } 500. Il traverse avec elles l'endothélium des vaisseaux sanguins et l'épithélium de la vessie en passant par les joints ou, pour une faible part, entre les vésicles.

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We are most grateful for the skilful assistance of Mr.B. R. Dixon and the partial support of the Australian Research Grants Committee.     

The permeability of large lymphatics to ions,studied with the electron microscope

Résumé Les petites molécules s'échappent des grands vaisseaux lymphatiques grâce aux jonctions endothéliales intercellulaires, qui ne laissent pas passer les grandes molécules.     

An electron microscope study of the anal organs ofDrosophila larvae

Zusammenfassung Elektronenmikroskopische Untersuchungen des Analorgans bei Drosophilalarven zeigten, dass die cuticulare Oberfläche dieses Organs durch Einstülpungen der Epicuticula vergrössert wird. Die an die Cuticula angrenzende Plasmamembran der Hypodermiszellen bildet zahlreiche Faltungen. Je nach der Salinität des Aussenmediums weist die Anzahl der Plasmamem-branfaltungen und der im Cytoplasma lokalisierten Mitochondrien regulatorische Veränderungen auf.

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This work was supported by grants from the Schweizerischer Nationalfonds and the Georges und Antoine Claraz-Schenkung.