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  • Pinealocytes  (8)
  • Ultrastructure  (5)
  • pineal  (5)
  • 1
    ISSN: 1435-1463
    Keywords: Melatonin ; 5-methoxytryptophol ; HIOMT ; pineal ; retina ; Harderian gland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The day and night rhythms in the activity of HIOMT in the formation of melatonin and of 5-methoxytryptophol have been determined in the pineal, retina and Harderian gland of the adult male golden hamster. In all hamsters used there was no detectable HIOMT activity in the deep pineal. In the superficial pineal HIOMT activity, involved in the synthesis of melatonin (Mel), was observed to be high at the end of the dark period and at the middle of the light period. Considering the HIOMT activity involved in the production of 5-methoxytryptophol (5-MTL), an increase in 5-MTL synthesis was observed only during the light period. Comparing the peak of Mel-production with that of 5-MTL it appears that during the light period the pineal produces more 5-MTL than Mel. In the Harderian glands, the circadian course of HIOMT activity involved in the synthesis of Mel seems to run parallel to that of the enzyme implicated in 5-MTL synthesis, both being stimulated at the end of the dark period. The activity of HIOMT in 5-MTL production is, however, always approximately 2 times higher than for Mel synthesis. In the retina the synthesis of Mel and 5-MTL is not significantly higher during the dark period than during the light period. However, the production of 5-MTL is larger than that of Mel. It appears that (1) with the exception of the end of the dark period, the extra-pineal synthesis of Mel and 5-MTL is always higher than that in the pineal; (2) the circadian synthesis of 5-methoxyindoles is different in each organ, and (3) in the pineal the circadian activity of HIOMT involved in 5-MTL formation is different from that of the same enzyme involved in the formation of Mel. The results are discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neural transmission 40 (1977), S. 47-68 
    ISSN: 1435-1463
    Keywords: Pinealocytes ; bat ; ultrastructure ; secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of the pinealocytes of noctule bats, mammals which live most of the time in darkness or very low light intensities, was examined and compared with the pinealocytes of other mammals. Two different populations of pinealocytes (I and II) were observed. They differ in general aspect, in location and especially in their content of cell organelles involved in synthetic processes. Mitochondria, ribosomes, lysosomes and lipid inclusions were present in the perikaryon of pinealocytes of both populations. In the pinealocytes of population I some granular vesicles, of presumed Golgi origin, and some other structures were observed. Pinealocytes of population II are characterized by many glycogen granules, more or less associated with a large vacuolar system. Moreover, some small vacuoles originating from cisterns of the granular endoplasmic reticulum and containing flocculent material of a moderate electron density are described. The possibility is discussed that these small vacuoles are involved in one of the secretory processes of the pineal gland while the granular vesicles of the pinealocyte of the population I are the products of another.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neural transmission 40 (1977), S. 289-304 
    ISSN: 1435-1463
    Keywords: Pinealocytes ; mammals ; secretory process
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The different categories of cells described by many authors in the pineal gland of mammals have been critically considered. In some mammalian species, two different populations of pinealocytes have been observed. To each of these populations a specific secretory process can be attributed. One is characterized by the formation of granular vesicles originating from the Golgi apparatus, the other by the formation of material directly from the cisterns of the granular endoplasmic reticulum. Both of these secretory processes appear to be also present in the pineal of the mole, the hedgehog, and the rat, mammals in which generally only one population of pinealocytes has been described. The physiological consequences of these findings have been discussed.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1435-1463
    Keywords: Pinealocytes ; mole ; sexual cycle ; ultrastructure ; paracrystalline structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Resume L'évolution quantitative de quelques paramètres ultrastructuraux (structures paracristallines, appareils de Golgi, grains de sécrétion) des pinéalocytes de la taupe, a été suivie pendant les différentes phases du cycle sexuel. Cette étude a permis de montrer une augmentation du nombre des structures paracristallines et des appareils de Golgi pendant la phase de pleine activité sexuelle chez les mâles et pendant l'œstrus, la gestation et la lactation chez les femelles. De plus, l'apparition d'un phénomène de vacuolisation des pinéalocytes a été observée pendant le proestrus. Ces résultats semblent démontrer d'étroites relations entre l'activité endocrine de l'axe adénohypophyse-gonades et l'accroissement des synthèses des pinéalocytes. Aucune évolution du nombre de grains de sécrétion n'a été observée pendant les différentes phases du cycle sexuel.
    Notes: Summary Changes of some ultrastructural parameters (paracrystalline structures, Golgi apparatus, secretory granules) in mole pinealocytes were quantitatively studied during the various phases of the sexual cycle. An increase in quantity of paracrystalline structures and of the Golgi apparatuses was demonstrated during the period of high sexual activity in male pinealocytes and during oestrus, gestation and lactation in female pinealocytes. Moreover, the appearance of vacuoles in female pinealocytes was observed during pro-oestrus. These results seem to demonstrate close relationship between the endocrine activity of the hypophyseo-gonadal axis and the synthesis of some compounds by the pinealocytes. No increase in the quantity of secretory granules was observed during the various phases of the sexual cycle studied.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1435-1463
    Keywords: 5-methoxytryptamine ; pineal ; hamster ; reproductive function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Subcutaneous implantation of 5-methoxytryptamine-filled silastic capsules overcomes, in natural as well as in experimental conditions, the inhibitory effect of short photoperiod on the gonadal axis. The results obtained are similar to those obtained after pinealectomy. They indicate that 5-methoxytryptamine when constantly available presents, like melatonin, a progonadal (or counter-antigonadal) effect. Evidently, 5-methoxytryptamine, like melatonin, is involved in the control of the reproductive function.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1435-1463
    Keywords: melatonine ; 5-methoxytryptamine ; pineal ; hamster ; photo-period
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Late-afternoon-administered 5-methoxytryptamine (5-MT) induces gonadal atrophy in male hamsters kept under long photoperiods (14 hL/ 10 hD). Morning-injection of 1mg 5-MT does not show antigonadal effects. However, 1 mg melatonin (MEL) administered in the morning completely prevents the antigonadotropic effect of 5-MT administered in the late afternoon. This result is specific of MEL since morning injections of 1mg 5-MT do not present this counterantigonadotropic property. When interpreted according to Reiter's concept of down-regulation of MEL receptors, these results suggest that the physiological effects of 5-MT are indirectly due to MEL.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neural transmission 55 (1982), S. 95-99 
    ISSN: 1435-1463
    Keywords: 5-methoxytryptamine ; hamster ; pineal ; photoperiod
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Daily (6 days on 7) subcutaneous injections of 25μg of 5-methoxytryptamine in saline 0.9% into intact male hamsters given between 9.00 and 9.30 (lights on from 8.00 to 18.00; 10hL/14 hD) during 8 weeks block short photoperiodically induced testicular atrophy. Under these experimental conditions, however, this blockage is not total since the weight of the testes and of the accessory sex organs of the pinealectomized hamsters is higher than that of treated animals. The results indicate that 5-MT, like melatonin, is a physiologically active compound implicated in the control of the reproductive function.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0878
    Keywords: Pinealocytes ; Photoreceptor cells ; Bat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Des dèrivès ciliaires identiques aux segments externes des photorècepteurs rudimentaires prèsents dans l'èpiphyse des vertèbrès infèrieurs ont ètè observès dans quelques pinealocytes de la Noctule (chauve-souris) adulte. Quelques autres observations ont, de plus, permis de classer les pinéalocytes de la population I en plusieurs types, l'un d'entre eux prèsentant de nombreuses ressemblances morphologiques avec les photorècepteurs rudimentaires. Ces diffèrentes observations confirment une nouvelle fois le concept de la lignèe de cellules sensorielles dans l'organe pinèal des vertèbrès. L'appartenance de la deuxième population de pinealocytes à la lignèe des cellules sensorielles est discutèe.
    Notes: Summary An electron microscopical investigation of the pineal gland of the adult noctule bat revealed the presence of some peculiar ciliary derivatives, similar to the club-shaped outer segment of rudimentary photoreceptor cells in the pineal organ of nonmammalian vertebrates. The pinealocytes of population I can be classified in several morphological types, one of them displaying morphological features resembling those of rudimentary photoreceptor cells. These results reconfirm the concept of the sensory cell line in the vertebrate pineal organ. The question whether the pinealocytes of population II belong to the same sensory cell line is discussed.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 216 (1981), S. 253-271 
    ISSN: 1432-0878
    Keywords: Pinealocytes ; Cell populations ; Bat ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the pineal gland of the pipistrelle bat two different populations of pinealocytes and glial cells were observed electron microscopically. The pinealocytes of populations I and II differ in their content of metabolically active cell organelles. In the pinealocytes of population I, granular vesicles originating from the Golgi apparatus were found in the perikaryon and especially in the endings of the pinealocyte processes. Granular vesicles appeared to be more numerous in hibernating nulliparous females. The pinealocytes of population II are characterized by the presence of small cytoplasmic vacuoles, probably originating from cisternae of the granular endoplasmic reticulum and containing flocculent material of moderate electron density. The classification of the pinealocytes belonging to population II is discussed.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 254 (1988), S. 247-249 
    ISSN: 1432-0878
    Keywords: Pinealocyte ; Light exposure ; Ultrastructure ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Although it is generally known that light strongly influences N-acetyltransferase activity and melatonin production in the pineal gland, little information is available concerning morphological changes following light exposure. As exposure of rats to a short light pulse at night rapidly depresses melatonin synthesis, we decided to determine whether this experimental condition produces rapid changes in the pinealocyte organelles. A 30-min light pulse at night (six hours after lights out) provoked rapid changes in the relative volumes of some pinealocyte organelles. The volume fractions of mitochondria, Golgi apparatus and lipid droplets, and the numbers of dense-core vesicles and “synaptic” ribbons decreased, whereas the volume fraction of lysosomes increased. There were no differences in the volumes of granular endoplasmic reticulum and vacuoles containing flocculent material in those animals exposed to light compared with control animals. These results indicate that a short light pulse at night causes ultrastructural changes that can be interpreted as morphological features of diminished activity of pinealocytes.
    Type of Medium: Electronic Resource
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