Pinealocyte

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

Cerebrospinal fluid-contacting neurons, sensory pinealocytes and Landolt's clubs of the retina as revealed by means of an electron-microscopic immunoreaction against opsin.

Abstract: Opsin-immunoreactive sites of hypothalamic cerebrospinal fluid (CSF)-contacting neurons, pinealocytes and retinal cells were studied in various vertebrates (Carassius auratus, Phoxinus phoxinus, Triturus cristatus, Bombina bombina, Rana esculenta) by means of postembedding immuno-electron microscopy with the use of the protein A-gold labeling method. The retina of the rat served as a general reference tissue for the quality of the immunocytochemical reaction.

5HT7 receptors in the rodent suprachiasmatic nucleus.

Abstract: Serotonergic modulation of circadian rhythms in rodent model preparations has received considerable attention over the past decade. Investigators have also been trying to determine which of the many serotonin receptor subtypes may be mediating the effects of serotonin in the suprachiasmatic nucleus, the location of the biological clock that generates the circadian rhythms. A single study in 1993 using the in vitro rat hypothalamic slice preparation suggested that serotonergic modulation of circadian rhythms at the level of the suprachiasmatic nucleus was acting via the newly discovered 5HT7 receptor subtype. Since that initial claim, serotonin modulation of circadian rhythms at the level of the suprachiasmatic nucleus has generally been attributed to 5HT7 receptor activation. However, when trying to cite relevant literature in support of 5HT7 involvement, it becomes evident that attributing rhythm-related serotonin activity in the suprachiasmatic nucleus to 5HT7 receptors may be somewhat premature. There are issues related to pharmacological specificity, species-specific results, and significant knowledge gaps that necessitate a careful review of the literature to make a judgment as to whether 5HT7 receptors are responsible for serotonergic activity in the rodent suprachiasmatic nucleus. In addition, there is sufficient data available at present to make an initial determination as to the degree of 5HT7 receptor involvement at any level in the generation or modulation of circadian rhythms in rodent species.

Morphologic evidence for differentiation of pinealocytes from photoreceptor cells in the adult noctule bat (Nyctalus noctula, Schreber)

Abstract: 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.

Electron microscopic observations on neuron-like cells in the ground squirrel pineal gland

Abstract: Ultrastructural details of neuron-like cells as well as synaptic nerve endings in the pineal gland of the ground squirrel are described. The neuron-like cells are situated mainly in the distal portion of the gland. Since the neuron-like cells differ considerably from the pinealocytes and exhibit cytological features characteristic of nerve cells, they are presumably true neurons. The cell bodies or processes of the neuron-like cells receive many synapses. The nerve endings synapsing on these cells contain numerous small non-granulated and some large granulated vesicles but no small granulated vesicles. These synaptic nerve endings are rather abundant within the parenchyma but they are also found in perivascular spaces ensheathed completely or partially by the Schwann cell cytoplasm. Similar nerve endings occasionally make typical synaptic contacts with the cell bodies or processes of the pinealocytes. Since the adrenergic nerve endings do not form synapses on the pinealocytes in the ground squirrel, it is clear that nerve endings other than adrenergic ones also distribute within the pineal gland of this animal. These synaptic nerve endings may contribute, at least to some extent, to the innervation of the ground squirrel pineal gland, whether they are derived from the nerve fibers penetrating the pineal gland or from the neuron-like cells.