Search results for "Pineal organ"
showing 7 items of 7 documents
Electrophysiological evidence for circadian rhythmicity in a mammalian pineal organ
1980
Long-term electrophysiological recordings from the guinea-pig pineal organ show that three types of intrinsic cells can be distinguished: (i) Cells showing constant firing rates over periods of up to 24 hours. (ii) Cells which are highly active during the day and show a low firing rate during the night. (iii) Cells which exhibit low activity during the day and enhanced activity during the night; these cells can be strongly inhibited by 1 min of light given during the night. Both the light- and darkness-activated cells show activity patterns which closely follow season-dependent differences in day- and night-lengths. In addition, both cell types show an oscillatory pattern in maintained acti…
Effects of an Earth-strength magnetic field on electrical activity of pineal cells
1980
Although magnetic fields can influence biological systems, including those of man and other vertebrates1–5, no central nervous structure has been identified that might be involved in their detection. From a theoretical point of view, the pineal organ might be such a structure for the following reasons: (1) It is involved in the regulation of circadian rhythms6 and is thus essential for migratory restlessness (‘Zugunruhe’)7. Orientation at that time can be altered by an artificial magnetic field (MF) with a direction differing by 90° from that of the Earth. Circadian rhythms can be inhibited from phase shifting by compensation of the Earth's MF and can be influenced by an artificial MF8. (2)…
Perspectives of Comparative Anatomy of the Mammalian Pineal Gland
1983
As the precise role of the pineal gland has been established in a few mammalian species only, every effort should be made to elucidate the function of this potentially important neuroendocrine organ in as many species as possible. One way in which the morphologist can contribute to reach this goal is to carry out comparative studies. Comparative anatomical studies with respect to the pineal gland can be, and should be, carried out at different structural levels: (a) At the gross anatomical level; (b) at the tissue level; (c) at the cellular level, and (d) at the level of cell organelles.
Electrophysiology of the Mammalian Pineal Gland: Evidence for Rhythmical and Non-Rhythmical Elements and for Magnetic Influence on Electrical Activity
1982
Although the mammalian pineal gland has been extensively studied by biochemical, pharmacological and morphological techniques, the precise nature of the intrinsic cells, the pinealocytes, was unknown for a long time. Biochemically the pinealocyte has been shown to be an endocrine cell synthesizing melatonin and other hormones. In view of the importance of the mammalian pineal as a neurotransducer, and of the limited usefulness of the methods mentioned, an attempt was made to characterize the cells electro-physiologically.
The Use of Electron Microscopy and Stereology in the Study of the Mammalian Pineal Gland
1983
Now that transmission electron microscopy (TEM) has been used for many years to study the pineal gland it is timely to evaluate what progress has been achieved by using this technique and to speculate which aspects of pineal research may benefit most by its application in the future.
Neuropeptide Y (NPY)-like immunoreactivity in the guinea pig pineal organ.
1986
Relatively little is known about mammalian pineal neuropeptides. In the present study neuropeptide Y-like immunoreactivity (NPY-LI) was examined in the guinea pig pineal gland. NPY-LI was restricted to few intrapineal nerve fibers of faint fluorescence intensity. They showed no preferential localization with regard to the different pineal portions. As catecholaminergic fibers are abundant in the guinea pig pineal gland, the scarcity of NPY-LI fibers indicates that in the pineal colocalization of noradrenaline and NPY-LI is not a regular feature, in contrast to other organs. The possibility exists that in the pineal NPY-LI fibers are not of peripheral sympathetic but of central origin.
Comparative Morphology of the Vertebrate Pineal Complex
1979
Publisher Summary This chapter explores whether there is evidence for the assumption that the mammalian pineal organ is a complex rather than a single organ with a uniform function. It is pointed out that the pineal organ is structurally very complex, especially in rodents. The uneven development of the pineal organ in rodents and the topographical relationships of the pineal organs in other mammalian orders have prompted a classification which is based on the shape, the size, and localization of the pineal organ. A tentative classification of the pineal organs of thoroughly studied species shows that closely related species have similar types of pineals. Based on the different localization…