Light and electron microscopic studies on capillaries of the goat cardiac muscle with special reference to the topographical relationship between the vessels and Purkinje fibers

The capillaries of the cardiac muscle were investigated in the goat by means of light microscopy, transmission electron microscopy and scanning electron microscopy, and the following results were obtained. The capillaries of the working cardiac muscles were numerous, arranged mainly parallel to the long axis of muscle cells and formed dense elongated networks. On the contrary, those of the terminal Purkinje fibers were relatively few in number, oriented in various directions and formed loose and circularly meshed networks surrounding the fibers. Such findings were discussed in correlation with the physiology and functional morphology of various types of the cardiac muscle cells.     

Bacterial transposons and the mechanisms of their transposition

The published data on molecular mechanisms of transposons movement inside and between genomes are reviewed. The replicative mechanism of transposition of the family of Tn3-like elements is discussed, as well as the modes of bacteriophage Mu, Tn9, Tn10, Tn903 transposition. The factors affecting the choice of transposition pathways are analysed.     

Apomorphine-induced upregulation of serotonin 5-HT2A receptors in male rats is independent from development of aggressive behaviour.

The [3H]ketanserin binding characteristics in the apomorphine-induced aggressive and nonaggressive adult male Wistar rats were studied. Repeated apomorphine (0.5 mg/kg, once daily) treatment gradually induced aggressive behaviour in sixteen animals from twenty. Thereafter the animals were retrospectively divided into apomorphine-induced aggressive and nonaggressive group. The maximal number of the [3H]ketanserin binding sites was increased in the apomorphine-treated animals in the frontal (233.9+/-26.5, 364.6+/-31.7, and 367.0+/-34.8 fmol/mg protein for the vehicle, apomorphine-nonaggressive, and apomorphine-aggressive group, respectively) and cerebral cortex (164.2+/-6.7, 289.7+/-29.3, and 249.0+/-15.4 fmol/mg protein for the vehicle, apomorphine-nonaggressive, and apomorphine-aggressive group, respectively). In conclusion, our experiments demonstrate that repeated apomorphine treatment upregulates the maximal number of the 5-HT2A receptors in rat frontal and cerebral cortex as measured by [3H]ketanserin binding and this phenomenon is independent from the development of aggressive behaviour.     

Degeneration of the laminated corpuscles (of Vater--Pacini) following colchicine application to a nerve]

Laminated pacinian corpuscles from the cat mesentery have been studied morphologically and morphometrically after nerve section and colchicine application to the nerve and the results obtained are represented. Similar interventions in the nerve produce changes in the receptors resembling those of wallerian type degeneration, degeneration rate after sectioning being higher than after colchicine application. At early stages after colchicine application the internal cone and its nuclei increase in size. The data obtained suggest the nuclei of the internal cone to be under neurotrophic control of the sensory neuron that might be realized via axoplasmic transport of substances.     

Additive stimulation of hepatic putrescine production by glucagon and insulin after partial hepatectomy in rats

When rats received glucagon or insulin every 2 h after partial hepatectomy (Hx), hepatic putrescine content was increased above control levels at 6 and 12 h, respectively. When the two hormones were combined, the increased levels were additive. Hepatic ornithine decarboxylase activity was above control levels at 12 h after insulin treatment. Hepatic spermidine N1-acetyltransferase activity was enhanced at 6 h only when glucagon was dosed. Putrescine administration from 0 to 4 h or from 6 to 10 h increased hepatic DNA synthesis to similar levels 22 h after Hx. These results suggest that glucagon and insulin additively stimulate hepatic putrescine production after Hx. This may explain the cooperative stimulation of liver regeneration by both hormones.