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[On the growth of cultured bovine aortic endothelial cells. Preliminary observations on ultrastructural morphology by freeze-etching and quantitation of growth rate by phase contrast microscopy: effect of glycosaminoglycans].

Bovine aortic endothelial cells (BAEC), detached from thoracic aorta by collagenase treatment, have been studied after adding a mixture of glycosaminoglycans (GAGs) (the composition of which has been studied by Casu et al. -6), at different concentrations. GAGs at the concentration of 90 mg/100 ml of medium (Dulbecco's modification of Eagle's MEM with 10% foetal calf serum) produced an increase in the growth speed. We have quantitized these data both by counting the number of cells 24 h after trypsinization in phase-contrast-microscopy, and by measuring the time necessary to reach a certain number of influences. Ultrastructural observation at transmission electron microscope after freeze-etching preparation, didn't show any relevant modification either in the organization of cell membrane or in the cytoplasmatic structures. In some observations a conspicuous increase of "vesicular openings" ("pits") on the plasmatic membrane was evident. Statistical evaluation of this phenomenon is under consideration.

Animals↗

[A study of the polyploid nuclei of the giant trophoblast cells of several species of rodents using phase contrast microscopy].

Patterns of chromosome morphology in high polyploid trophoblast nuclei of placenta were compared in the rat, rabbit and Microtus arvalis. In the rat and rabbit placenta two types of nuclei were recognized. Some nuclei have ribbon-like chromosomes, while others display thin oligotene fibrils with paired chromomers evenly distributed throughout all karyoplasm. In the latter case, the polytenic structure of chromosomes is seen preserved only near the nucleoli. In the rat and rabbit trophoblast nuclei, the ribbon-like polytene chromosomes could be distinguished only with phase contrast microscopy. In the trophoblast nuclei of Microtus arvalis polytene chromosomes were found only at early stages of embryonic development (9 day old embryo). On later stages of cell differentiation, the chromosomes or chromosome rosetts are seen. Similarities in mechanisms of polyploidization in the high polyploid nuclei of Diptera and in trophoblast nuclei of rodents are discussed.

Animals↗

Recording of single-particle hysteresis loops with differential phase contrast microscopy.

The magnetic behaviour of laterally patterned structures on a micrometer or nanometer scale in external magnetic fields can be described by their hysteresis loops. However, it is very difficult to record the hysteresis loop of a single (sub-) micron-sized particle. Furthermore, extensive calculations are necessary in order to interpret the shape of the loop and to conclude the micromagnetic domain configuration in the sample from the hysteresis loop only. We have developed a technique which yields both the hysteresis loop and the magnetic domain structure simultaneously. This method uses differential phase contrast microscopy and a microscope with remote control capability for the automatic recording of a single-particle hysteresis loop.

Journal Article↗