Search results for "Microscopy"
showing 10 items of 3390 documents
Ultrastructural observations on the central innervation of the guinea-pig pineal gland.
1981
In the present study the central innervation of the guinea-pig pineal gland was investigated. The habenulae and the pineal stalk contain myelinated and non-myelinated nerve fibres with few dense-cored and electron-lucent vesicles. Some myelinated fibres leave the main nerve fibre bundles, lose their myelin-sheaths and terminate in the pineal gland. Although direct proof is lacking, the non-myelinated fibres appear to end near the site where the bulk of the myelinated fibres are located. Here a neuropil area exists where synapses between non-myelinated fibre elements are abundant. Neurosecretory fibres were also seen. The results support the concept of functional interrelationships between h…
Pineal ?synaptic? ribbons and spherules during the estrous cycle in rats
1983
In previous studies pineal "synaptic" ribbons have been shown to undergo striking numerical changes under various physiological and experimental conditions and to be regulated by beta-adrenergic mechanisms. The aim of the present investigation was to study the numbers of pineal "synaptic" ribbons and spherules in Wistar rats throughout the estrous cycle and to compare them with those in males. There were no statistically significant differences in the numbers of ribbons and spherules between males and females and in the females at the different stages of the estrous cycle, indicating that the structures in question, in vivo, do not appear to be regulated by naturally occurring changes of se…
Simultaneous determination in situ of DNA fragmentation and 8-oxoguanine in human sperm.
2009
Deoxyribonucleic acid fragmentation and oxidative DNA damage were simultaneously determined in the same sperm cell, incubating with an 8-oxoguanine DNA probe on human spermatozoa processed by the sperm chromatin dispersion test. The assay was validated by incubation with agents that induce DNA fragmentation with or without oxidative base damage. In all samples examined, increased levels of 8-oxoguanine were present only in those spermatozoa with fragmented DNA, suggesting a link between both DNA damage types.
Electron microscopic study on the larval and adult corpus allatum of Oncopeltus fasciatus dallas (insecta, heteroptera)
1973
1. The ultrastructure of the corpora allata of last larval instars and adults of Oncopeltus was studied. The unpaired gland undergoes submicroscopic alterations and shows signs of degradation in old animals. The organ is partly covered and penetrated by corpus cardiacum tissue. Axons with different types of neurosecretory granules form synaptoid contacts with the corpus allatum cells.
Prostasome-like vesicles stimulate acrosome reaction of pig spermatozoa
2007
Abstract Background The presence of small membranous particles characterizes the male genital fluids of different mammalian species. The influence of semen vesicles, denominated prostasomes, on sperm functional properties has been well documented in humans, but their biological activity is scarcely known in other species. The present work investigated prostasome-like vesicles in pig semen for their ability to interact with spermatozoa and to affect acrosome reaction. Methods Prostasome-like vesicles have been isolated from pig seminal plasma by high-speed centrifugation and Sephadex G-200 gel chromatography. Morphology of purified vesicles has been checked by scanning electron microscopy wh…
No Correlation of Pineal "Synaptic" Ribbon Numbers and Melatonin Formation in Individual Rat Pineal Glands
1984
As previous circadian studies of pineal "synaptic" ribbon numbers and melatonin formation suggested that a positive correlation of the two variables exists, in the present investigation this problem was examined in individual pineal glands of rats killed at 1200 h and 2400 h, respectively. For this purpose, one half of the gland was processed for electron microscopy and the ribbons were counted in an area of 20,000 micron2 tissue; in the other half serotonin N-acetyltransferase (NAT) activity and melatonin content were determined. No correlation was found to exist between ribbon numbers and pineal NAT activity, pineal melatonin levels and serum melatonin levels, either at day- or at nightti…
In vitro effects of putative neurotransmitters on synaptic ribbon numbers and N-acetyltransferase activity in the rat pineal gland
1992
The pineal contains a large number of classical transmitters and neuropeptides. Some of these neurochemicals are involved in the regulation of serotonin N-acetyltransferase (NAT) activity and hence in melatonin synthesis. Synaptic ribbons present in the pineal gland also exhibit a numerical day/night rhythm parallel to that of NAT activity. There is scarcity of information regarding the regulation of synaptic ribbon (SR) numbers. In the present study, we have investigated in vitro effects of a number of classical neurotransmitters and neuropeptides. NAT activity was used to monitor melatonin synthesis under the experimental conditions used. Norepinephrine (NE), Delta sleep-inducing peptide …
Quantitative analysis of "synaptic" ribbon profiles in the pineal complex of male and female Pirbright-White guinea pigs.
1990
Previous studies have pointed in the direction of sex differences as well as regional differences in the pineal gland of guinea pigs. In the present investigation these aspects were studied at the electron-microscopic level by quantitating different types of “synaptic” bodies, intrinsic to pinealocytes. The two major types of “synaptic” organelles, ribbons and spherules, did not exhibit regional or sex differences. “Synaptic” structures intermediate in appearance to ribbons and spherules were significantly larger in number in males in the distal region of the pineal gland, compared to females. As previous studies have shown that ribbon and spherule numbers undergo characteristic changes dep…
The effects of short pulses of light at night on numbers of pineal "synaptic" ribbons and serotonin N-acetyltransferase activity in male Sprague-Dawl…
1986
To characterize further the functionally enigmatic "synaptic" ribbons (SR) of the mammalian pineal gland and to study possible relationships to melatonin synthesis, in the present investigation rats were exposed to short pulses of light at night when both SR numbers and serotonin N-acetyltransferase (NAT) activity are high in comparison to day-time values. Male Sprague-Dawley rats were killed at 13:00 and 01:00 h, respectively, and at 01:10 and 02:00 h after exposure to light for 10 and 60 min, respectively. The pineals were rapidly taken out and cut sagittally in half. One half was processed for electron-microscopic quantitation of SR numbers and the other half for NAT determinations. It w…
Synaptic ribbons of the rat pineal gland: responses to in-vivo and in-vitro treatment with inhibitors of protein synthesis.
1990
To elucidate the role of protein synthesis in the nocturnal increase of synaptic ribbons in the rat pineal gland, actinomycin-D, which inhibits transcription, and cycloheximide, an inhibitor of translation, were used. To assure that the drugs were effective and to relate morphological changes to pineal biosynthetic phenomena, the activity of N-acetyltransferase and levels of pineal indoleamine were measured. Results of in-vivo, short-term and long-term treatment with either drug suggest that transcription of proteins related to synaptic ribbon formation occurs during the first half of the light phase, whereas translation takes place during the first few hours of the dark phase. In contrast,…