Observations on calcareous corpuscles using a scanning electron microscope

Summary Calcareous corpuscles were observed in a scanning electron microscope, and the presence of Ca was examined by means of elemental X-ray analysis.     

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.     

On the formation of the myotomes in avian embryos. An experimental and scanning electron microscope study

Summary The formation of the myotomes to chick embryos was studied by using experimental and scanning electron microscope techniques. With the aid of the quail-chick marker system, it was demonstrated that the dermatome gives rise to the myotome plate. SEM studies support the conclusion that the myotome cells originate only from the edges of the dermatome.Supported by the Deutsche Forschungsgemeinschaft (Ch 44/2).     

A scanning electron microscope method for the examination of glass microelectrode tips either before or after use

Zusammenfassung Mikroglaselektroden wurden im rasterelektronenmikroskopischen Dunkelfeld transmissionsoptisch ohne Metallbeschichtung untersucht, wobei die Elektroden nicht beschädigt werden und für physiologische Ableitungen wieder benützt werden können.

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I wish to thankR. D. Purves for his advice and for the use of the resistance measuring equipment. This work was supported by the Australian Research Grants Committee and the National Heart Foundation of Australia     

A new device for electron microscope autoradiography of whole cultured cells

Summary A new procedure which enables us to observe whole cultured cells autoradiographically by electron microscopy is described. By this method, only a relatively small amount of radioisotope and a relatively short exposure period are needed to get a large enough number of silver grains over the cell. The location of radioactive substances can be examined in relation to internal cell structures, especially the nucleus.     

Changes in rat erythrocyte membrane induced by delta 1-tetrahydrocannabinol, scanning electron microscope study.

Although some biochemical dose-dependent effects are revealed in erythrocytes exposed to delta 1-tetrahydrocannabinol (THC) already at concentrations well below 10 microM, marked morphological changes of the erythrocyte membrane become evident, by scanning electron microscopy, only at THC concentrations beyond 15 microM. These observations provide evidence additional to previous chemical and physical studies, in which 15 microM is found to be a critical concentration with respect to the effects of TCH on erythrocyte membrane.     

Supramarginal cells in the rat pituitary cleft revealed by scanning electron microscopy

An unusual cell type consisting of free elements widely scattered over the marginal epithelium of the rat pituitary cleft is revealed by SEM. Most of these supramarginal cells characteristically have irregularly shaped cell bodies from which thin branched processes extend. Supramarginal cells bear resemblances to Kolmer (epiplexus) cells and to supraependymal cells of the brain ventricles. Their ultrastructural features make it probable that supramarginal cells are phagocytes, and can be regarded as scavengers of the cleft. Considering the close topographical association between the hypophysial cleft and the floor or the 3rd ventricle, supramarginal cells may be members of the motile macrophagic Kolmer cells populating the ventricular surfaces of the brain.     

Supramarginal cells in the rat pituitary cleft revealed by scanning electron microscopy

Summary An unusual cell type consisting of free elements widely scattered over the marginal epithelium of the rat pituitary cleft is revealed by SEM. Most of these supramarginal cells characteristically have irregularly shaped cell bodies from which thin branched processes extend. Supramarginal cells bear resemblances to Kolmer (epiplexus) cells and to supraependymal cells of the brain ventricles. Their ultrastructural features make it probable that supramarginal cells are phagocytes, and can be regarded as scavengers of the cleft. Considering the close topographical association between the hypophysial cleft and the floor or the 3rd ventricle, supramarginal cells may be members of the motile macrophagic Kolmer cells populating the ventricular surfaces of the brain.Work supported by grants from MPI-60%-193/84     

The recovery of electron microscope grids

Zusammenfassung Es wird ein einfaches Verfahren zur Reinigung elektronenmikroskopischer Trägernetzchen aus Kupfer beschrieben: Abflammen der Netzchen und nachfolgende Reduktion der gebildeten Oxydschicht durch Alkohol.     

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.     

Multinucleated cells in the retinal pigment epithelium: A scanning electron microscopic study

Summary Multinucleated cells in the retinal pigment epithelium of the albino rat are shown with the scanning electron microscope beside normal mononucleated cells. We suggest that such elements are formed during foetal life, owing to the absence of any mitotic activity in adult rats.     

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.