Showing papers on "Pinealocyte published in 1972"

Electron microscopic and experimental studies of the pineal organ in the white-crowned sparrow, Zonotrichia leucophrys gambelii

Abstract: The structure of the pineal organ of Zonotrichia leucophrys gambelii, as revealed by light- and electron-microscopy, resembles that of Passer domesticus (Oksche and Kirschstein, 1969; Ueck, 1970). The typical cellular element is the pinealocyte with certain basic structural features of the pineal photoreceptors of lower vertebrates (see Oksche, 1971). However, instead of the characteristic, cone-like outer segments, there are, as in other species of birds, only bulbous cilia with ectopic whorls of lamellae. This structure of the outer segment is, in a sense, contrary to the demonstration of synaptoid contacts, numerous unmyelinated, and occasional myelinated nerve fibers by electron microscopy. In Nissl preparations it was possible to demonstrate typical nerve cells. The pinealocytes of Z. l. gambelii are secretory; their Golgi complex forms granulated vesicles (800–1,400 A in diameter) that belong to the group of granular inclusions characteristic of monoamines. Autonomie nerve fibers course within the connective tissue capsule of the pineal organ. In many pinealocytes of Z. l. gambelii, the granular endoplasmic reticulum contains extensively expanded cisternae that are filled with a flocculent material and closely associated with bundles of filaments. In a number of cases such loop-like structures are selectively stainable with aldehyde fuchsin. It was not possible to demonstrate specific secretory activity in the supporting cells. Extirpation of the pineal organ in Z. l. gambelii had no definitely detectable influence on the photoperiodic control of testicular growth.

Transformation of centrioles in pinealocytes of adult guinea pigs

Abstract: Pinealocytes from adult guinea pigs contain conventional centrioles and microtubular sheaves composed of varying numbers of doublet and/or triplet tubules of indefinite length embedded in a dense matrix, which are assumed to be formed by elongation and dissociation of the centriolar wall. The observations suggest that one end of the wall of elongated centriolar formations may remain unbroken, while the other end may split into microtubular sheaves arranged in straight or skewed arrays. Additionally, maturing pinealocytes may possess two pairs of centrioles, of which some undergo lengthening and disintegration of the wall, giving rise to microtubular sheaves, while others remain unbroken. Cross-striated structures named denticulate or striped borders are often seen apposed to the elongated centriolar formations and are possible precursors of adjacent striated fibres.

Alterations in the distribution of yellow fluorescing rabbit pinealocytes produced by P-chlorophenylalanine and different conditions of illumination.

Abstract: Fluorescence Microscopy Changes in the density of yellow autofluorescent and serotonincontaining pinealocytes in the rabbit pineal gland have been studied under different experimental conditions such as p-chlorophenylalanine, environmental lighting and permanent darkness, using fluorescence microscopy. The yellow autofluorescent pinealocytes (Type II), particularly present in a circumscript area of the organ, increased in number during treatment of the animals with pCPA as well as during the night under environmental lighting conditions. This increase probably accurred at the cost of the decrease in number of serotonin-containing pinealocytes (Type I) in the same area, originally present. Moreover it could be demonstrated that under environmental lighting conditions both, the number of Type I and Type II cells, showed a day and night rhythm. During continuous darkness the circadian rhythm in the serotonin content of the Type I cells persists. Evidently, this rhythm is not controlled by exogenous environmental lighting conditions but endogenously. In contrast to the persisting circadian serotonin rhythm, no such fluctuations could be observed in the yellow autofluorescing compound in the Type II cells.