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Pinealocyte

About: Pinealocyte is a research topic. Over the lifetime, 1605 publications have been published within this topic receiving 55609 citations.


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Book ChapterDOI
TL;DR: This chapter examines whether pineals of higher vertebrates still retain the potency to differentiate into their ancestral phenotypes, into lens and various other ocular cells, when cultured in vitro, and investigates the multiplicity of differentiation of pineals.
Abstract: Publisher Summary The pineal complex of lower vertebrates is a photoreceptive organ known as the “median eye” that furnishes function and morphology comparable with two lateral eyes. In the course of phylogenic development, the pineal changes its major function from photoreceptive to endocrine. A number of pinealogists have suggested repeatedly that photoreceptive cells in the pineal of lower vertebrates are the direct ancestors of endocrine pinealocytes of higher vertebrates. It has been well demonstrated that nonlenticular cells of vertebrate eyes can convert their cell types, or transdifferentiate, into lens in cell culture conditions. This chapter, therefore, examines whether pineals of higher vertebrates still retain the potency to differentiate into their ancestral phenotypes, into lens and various other ocular cells, when cultured in vitro . Recent results along this line indicate that pineals of higher vertebrates are provided with an unexpectedly wide repertoire of differentiation. This system may not only offer another interesting example of transdifferentiation, but also provides a unique opportunity to analyze the nature of an exogenous cue by which multipotent cells can select a given pathway of differentiation. The chapter also reviews studies on the multiplicity of differentiation of pineals.

12 citations

Journal ArticleDOI
TL;DR: It appears that non-alpha1-adrenergic-regulated PKC possesses a regulatory rote in NO-induced cyclic GMP formation, which is likely to interfere with cytosolic guanylyl cyclase activation.

12 citations

Journal ArticleDOI
TL;DR: It is suggested that the macrophages/microglia in the pineal gland are active phagocytes which are also probably involved in the immunoregulatory function in the gland.
Abstract: The pineal gland of rats of various ages (1-21 days old) was examined by immunohistochemistry and electron microscopy. Numerous widely distributed cells identified as macrophages/microglia were immunoreactive with the monoclonal antibodies OX-42, OX-18, OX-6, and ED1, indicating that they expressed complement type 3 (CR3) receptors, major histocompatibility complex class I and II antigens, and antigens of monocyte/macrophage lineage as detected by the antibodies, respectively. Following an intraperitoneal injection of rhodamine isothiocyanate (RhIC) in all age groups, the cells emitted a bright fluorescence. They were also labeled by horseradish peroxidase (HRP), as demonstrated in both light and electron microscopy. An HRP reaction was observed in vesicles and lysosomes at the ultrastructural level. A remarkable feature was the uptake of these tracers by pinealocytes. In light microscopy, the pinealocytes showed a punctate reaction product 3-24 hours after HRP injection. By electron microscopy, the reaction product was observed in vesicles, lysosomes, and some rod-like structures in the cytoplasm. On the basis of their immunophenotypic features, it is suggested that the macrophages/microglia in the pineal gland are active phagocytes which are also probably involved in the immunoregulatory function in the gland. The avid uptake of RhIC and HRP from the circulation by these cells suggests that serum-derived substances that may gain access to the parenchyma of the gland are being constantly monitored. The labeling of pinealocytes with HRP suggests that the functional activities of these cells are being modulated by serum-derived substances.

12 citations

Journal Article
TL;DR: Using enzyme histochemistry and immunohistochemistry, the presence of NOS has been confirmed in the pineal gland of some species and NOS immunoreactivity has been shown to be present in pinealocytes of the rat and bovine but not in the sheep.
Abstract: The recent discovery of nitric oxide (NO) as a biological messenger molecule with unique characteristics has opened a new field in pineal research. This free radical gas is synthesized by the enzyme nitric oxide synthase (NOS) from L-arginine. The activation of adrenoreceptors in the membrane of the pinealocytes mediates the increase in NO through a mechanism that involves G proteins. In the pinealocyte, NO stimulates guanylyl cyclase resulting in an increased intracellular content of cGMP. The role of cGMP in pineal metabolism, however, is still enigmatic Using enzyme histochemistry and immunohistochemistry, the presence of NOS has been confirmed in the pineal gland of some species. In the rat and especially in the sheep, NOS is located in nerve fibres innervating the gland. These nerve fibres also contain the neuropeptides vasoactive intestinal peptide (VIP) and peptide histidine isoleucine (PHI), and are probably of parasympathetic origin. In cell cultures and tissue sections NOS immunoreactivity has been shown to be present in pinealocytes of the rat and bovine but not in the sheep. Finally, NOS is also present in the endothelial cells of the blood vessels of the pineal gland. Accordingly, in the mammalian pineal gland, NO is synthesized in both presynaptic nerve fibers and pinealocytes, as well as in blood vessels. However, the anatomical location of NO synthesis varies considerably among species. NO released in the pineal gland, might influence both the pineal metabolism and the blood flow of the gland.

12 citations

Journal ArticleDOI
TL;DR: The melatonin content measured by radioimmunoassay was significantly higher in the pineal gland from intact females killed during the night compared with that of intact females dead during the day or of ganglionectomized females, and the discrepancy between the results obtained may arise because immunohistochemistry can detect very small amounts of melatonin.
Abstract: An antiserum raised against N-amino-3-propyl melatonin bound to a protein carrier was used to visualize melatonin by immunohistochemistry and to measure melatonin concentration by radioimmunoassay in the pineal gland of intact mink females killed throughout the 24 h cycle and females killed after a bilateral ablation of the cervical superior ganglion. Melatonin immunoreactivity revealed by immunofluorescence or by the peroxidase-antiperoxidase complex was observed in the cytoplasm of presumed pinealocytes of all the females. Circadian changes in pineal melatonin content were not visualized by immunohistochemistry; furthermore, immunoreactivity was also present in the pineal gland of the ganglionectomized females. However, the melatonin content measured by radioimmunoassay was significantly higher in the pineal gland from intact females killed during the night compared with that of intact females killed during the day or of ganglionectomized females. The discrepancy between the results obtained using the two methods may arise because immunohistochemistry can detect very small amounts of melatonin.

12 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202310
202219
202116
202011
201915
201817