A new dopaminergic terminal plexus in the ventral horn of the rat spinal cord. Immunohistochemical studies at the light and electron microscopic levels

Summary It has been thought that the ventral motor column in the rat spinal cord is virtually free of dopaminergic fibers. However, a new dopaminergic terminal plexus was visualized at all spinal levels in the ventral horn using electron as well as light microscopic immunohistochemistry.     

Fusion between a myogenic cell in the satellite cell position and undamaged adult myofibre segments

In this report we demonstrate for the first time that differentiating myogenic cells, geographically located between the plasmalemma and external lamina of myofibres in the satellite cell position³, can fuse directly with the plasmalemma of undamaged segments of mature myofibres.     

In vivo inactivation of transglutaminase during the acute acrylamide toxic syndrome in the rat

Summary The activity of liver and brain transglutaminase is rapidly lost following i.p. injection of acrylamide (50–200 mg/kg). Other enzymes investigated were not modified by the treatment, with the exception of brain enolase.     

Diabetes alters drug metabolism-in vivo studies in a streptozotozin-diabetic rat model

Summary The influence of experimental streptozotozin-induced diabetes on hepatic drug metabolism in vivo has been studied in rats, using¹⁴CO₂-exhalation after¹⁴C-aminopyrine injection. Male diabetic rats showed a decreased (–18%), females an increased (+19%)¹⁴CO₂-exhalation compared to controls, indicating altered hepatic drug metabolism due to diabetes.     

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     

FITC-dextrans as fluorescence and electron microscopic tracers in studies on capillary and cell permeability of the CNS

FITC-dextrans can be detected at the ultrastructural level as round electron dense particles, with no sign of distortion or aggregation. Because this tracer is a stable, non-toxic polymer of biological origin obtainable in a wide range of molecular weights, it may be useful for further studies of tissue permeability.     

FITC-dextrans as fluorescence and electron microscopic tracers in studies on capillary and cell permeability of the CNS

Summary FITC-dextrans can be detected at the ultrastructural level as round electron dense particles, with no sign of distortion or aggregation. Because this tracer is a stable, non-toxic polymer of biological origin obtainable in a wide range of molecular weights, it may be useful for further studies of tissue permeability.The author is grateful to Ms. H. Büscher and Ms. S. Klemt, Department of Pathology, for their excellent technical assistance.     

Peptide YY enhances NaCl and water absorption in the rat colon in vivo

Peptide YY (PYY) is thought to possess paracrine and endocrine functions. The highest concentrations of this peptide are in the colonic mucosa. The effect of PYY on electrolyte and water transport in the rat colon was studied in vivo. Under urethane anesthesia, rat colonic loops were perfused at a constant rate with physiological buffer solution containing phenol red as a nonabsorbable volume marker, and net movements of water, sodium, chloride and potassium in the perfused colon were determined every 10 min. Intravenous administration of PYY produced a dose-dependent increase in the net absorption of sodium chloride and water, as well as a decrease in the net secretion of potassium. PYY inhibited the reduction in net absorption of sodium chloride and water evoked by vasoactive intestinal peptide (VIP), but did not affect the VIP-evoked increase in net potassium secretion.These findings suggest that PYY acts as an enhancer of sodium chloride and water absorption and as an antagonist to VIP-induced secretion in the colon.     

Electron microscopic studies on hepatic cells in mice after the administration of glutathione mixtures

Zusammenfassung Anschwellung und Lysis von Mitochondrien im Reagenzglas (in vivo), durch Zugabe von Glutathiongemisch zur Nährlösung verursacht, wurde elektronenmikroskopisch geprüft. Die Mitochondrien wurden in Mäuseleberzellen nach i.p. Injektion zusammen mit dem Glutathiongemisch untersucht.     

In vitro morphological characterization of the bursal reticuloepithelial (REp) cells of chicken

Summary The REp cells of the bursa follicle medulla of chicken were isolated in vitro. Culture of the REp cells was maintained over a period of 10 days and the cells were observed at 3 and 10 days by means of transmission electron microscopy (TEM) and immunofluorescence. The use of an anticytokeratin monoclonal antibody confirmed their epithelial nature. TEM observations showed the presence of desmonsomes and tonofilaments, which are characteristic of epithelial cells. Furthermore, to some extent the cells regenerated in vitro the network they form in vivo. Though the growth rate becomes slower with time, the features of the REp cells do not significantly change.     

Comparison of the time courses of luteinizing hormone (LH) secretion rates during continuous stimulation by LH-releasing hormone (LH-RH) in vivo and in vitro

Summary The patterns of LH secretion during constant stimulation of the pituitary glands of estradiol-treated ovariectomized rats with a maximally stimulating amount of LH-RH in vivo and in vitro correspond with each other qualitatively and quantitatively. In vitro the changes with time of the LH secretion rate are somewhat retarded, especially the occurrence of desensitization.