Search results for "Pineal gland"

Effects of an earth-strength magnetic field on pineal melatonin synthesis in pigeons

1987

A Case Report of Adult Pineoblastoma Occurring in a Pregnant Woman.

2019

Background/aim Pineoblastoma of the adult age is an uncommon tumor with only 200 cases reported. A standardized approach for an optimal adjuvant strategy is currently lacking. The case presented herein also deals with the issue of central nervous system tumors in pregnancy. Case report A 21-year-old pregnant woman presented with massive hydrocephalus due to a mass in the pineal region detected with MRI. After positioning an urgent ventricular derivation, a cesarean section was performed. During a third ventriculocisternostomy, a biopsy revealed a pineoblastoma. After a maximal safe resection, postoperative craniospinal irradiation for a total dose of 36 Gy plus a sequential boost to the tum…

Ocular pseudomyasthenia: report of a case with a pineal region tumor.

1991

A case presenting with clinical features of ocular myasthenia and a false-positive edrophonium test is reported. Brain CT and MRI scan revealed a pineal region tumor histologically verified as germinoma. We recommend evaluating patients with clinical features of myasthenia gravis (MG) confined to the ocular muscles for intracranial mass lesions.

Anomalous occurrence of immunoreactive calcitonin cells in the thymus of the rat.

1982

In a study of the effect of pinealectomy on thyroid C-cell number, 8 animals out of 66 were found to have thymic tissue in close association with the thyroid. Cells containing immunoreactive calcitonin were found in all of the thyroids but in only one of the 8 pieces of thymus. These cells found in a piece of thymic tissue associated with the right thyroid lobe were located immediately under the capsule and did not form or associate with follicles. Unlike the other animals the rat with thymic calcitonin cells had an unequal distribution of C-cells between the left and right thyroid lobes, but the total number of thyroidal C-cells was the same as that of the other rats. Since the thymus prop…

Time-related changes in size of nuclei of pinealocytes in rats

1981

In a study of 96 adult male Sprague-Dawley rats, da- and time-related changes of the mean nuclear volume of pinealocytes were determined with the aim of testing the reproducibility of the karyometric findings described by Quay and Renzoni (1966). It is shown (i) that statistically significant differences exist between the central and peripheral mean volumes of pinealocyte nuclei/group of animals and time point (p less than 0.001), (ii) that the day and time related differences are statistically different in both regions (p less than 0.001), (iii) that in the center and periphery of the pineal body different diurnal patterns exist, and (iv) that the diurnal patterns are not parallel in the t…

No short‐term effects of high‐frequency electromagnetic fields on the mammalian pineal gland

1997

There is ample experimental evidence that changes of earth-strength static magnetic fields, pulsed magnetic fields, or alternating electric fields (60 Hz) depress the nocturnally enhanced melatonin synthesis of the pineal gland of certain mammals. No data on the effects of high-frequency electromagnetic fields on melatonin synthesis is available. In the present study, exposure to 900 MHz electromagnetic fields [0.1 to 0.6 mW/cm2, approximately 0.06 to 0.36 W/kg specific absorption rate (SAR) in rats and 0.04 W/kg in Djungarian hamsters; both continuous and/or pulsed at 217 Hz, for 15 min to 6 h] at day or night had no notable short-term effect on pineal melatonin synthesis in male and femal…

Pineal 'synaptic' ribbon numbers and melatonin synthesis of rat are resistant to guanethidine sympathectomy.

1995

Chemical sympathectomy is widely used to study the impact of the noradrenergic system on neuronal and neuroendocrine circuits. We tested the effects of intraperitoneal injections of guanethidine, an adrenergic neuron blocking agent, on selected functional parameters of the rat pineal gland which are known to be under sympathetic influence. The reliability of the method was demonstrated by the clear enophthalmus developed by experimental animals. However, neither the numbers of 'synaptic' ribbons nor melatonin synthesis differed between treated and control rats, both parameters exhibiting the nocturnal increase seen in intact animals. These results are in striking contrast to those obtained …

Magnetic Sensitive Pineal Cells in Pigeons

1982

The electrical activity of about 30% of a homing pigeon’s pineal cells can be altered by changing the horizontal or vertical component of the natural magnetic field, using two pairs of Helmholtz coils. The cells respond to a rapid and/or gradual change in the magnetic field with either excitation or inhibition. In some of the sensitive cells the responses to magnetic field changes could not be repeated.

Intramitochondrial crystalloids in rat pinealocytes.

1982

In the present study the rare occurrence of intramitochondrial crystalloid inclusions in the rat pinealocytes is described. They lie within the mitochondrial matrix and consist of a lattice of moderately electron-dense lines. Intersections at regular intervals form rhomboid-like subunits. The significance of these inclusions is not known.

The response to isoproterenol of synaptic ribbon numbers in the rat pineal gland changes during postnatal development

1995

Abstract In the mammalian pineal gland synaptic ribbons (SRs) are dynamic organelles of pinealocytes undergoing a day/night rhythm, with small numbers during daytime and significantly higher numbers at night, similar to the formation of the pineal hormone melatonin. Whereas the day/night rhythm of melatonin synthesis is adrenergically regulated, data on the adrenergic regulation of SR numbers in the rat pineal gland are at variance. While some authors have demonstrated that isoproterenol (ISO) stimulates SR numbers, others could not find any effect. To clarify the issue, we carried out identical experiments in two age groups. It was found that in male Sprague-Dawley rats, administration of …