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R D Yates

Publications and source records attributed to R D Yates.

At least 37 records · Page 2Linked to original sources
PubMed1981

Autoradiographic localization of alpha-bungarotoxin-binding sites in the carotid body of the rat.

Radioiodinated alpha-bungarotoxin (alpha-Bgt) was used to localize alpha-Bgt-acetylcholine receptors in the carotid body of the rat. The gamma spectrometer analyses indicated a high uptake of [125I] alpha-Bgt in carotid bodies incubated in vitro (1.51 fmole per organ). Incorporation of the isotope was effectively blocked by pretreatment of carotid bodies with d-tubocurarine and unlabeled alpha-Bgt, but not by atropine. Light microscopic autoradiography showed a heavy labeling of some parenchymal cells. Electron-microscopic autoradiography revealed that labeling was localized along the interface between parenchymal cells, especially where their cytoplasmic processes engage in complex interdigitations. The silver grain counts on electron-microscopic autoradiographs suggest that labelings are preferentially associated with the plasma membrane of certain Type I cells. It is suggested that these Type I cells in the rat's carotid body probably are provided with nicotinic acetylcholine receptors on their plasma membranes.

Animals↗
PubMed1981

Age-related alterations in epicardial arteries of spontaneously hypertensive rats.

Proximal portions of the left coronary arteries were examined microscopically in aging female normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). The age-related intimal alterations in SHR were largely limited to endothelial cells, which demonstrated a proliferation of organelles (most notably Weibel-Palade bodies). In the media, degenerative alterations appeared to be most marked near the medio-adventitial junction. Compared to WKY and increasing with age, the media of the SHR epicardial artery demonstrated an accumulation of extracellular elements that included basement membrane-like material, collagen fibers and debris. Complex carbohydrates, as determined with the silver methenamine reaction, were noted to accumulate in a lamellar fashion. Smooth muscle cells demonstrated an age-related tendency (which was exaggerated in SHR) toward development of invaginations and irregular profiles. These observations indicate that age-related structural alterations in epicardial arteries of SHR are progressive, and they support the concept that structural alterations in SHR coronary arteries may represent accelerated aging phenomena.

Age Factors↗
PubMed1980

An electron microscopic study of the baroreceptors in the internal carotid artery of the spontaneously hypertensive rat.

The carotid baroreceptor field of normotensive (NTR) and spontaneously hypertensive rats (SHR) examined in this study extends for about 0.5 mm along the length and about 1/3 to 1/2 of the circumference of the wall of the internal carotid artery opposite to the carotid body. The vascular wall of the baroreceptor field exhibits neither a marked dilation to form a carotid sinus nor histological differences in the intima and media compared to other parts of the carotid artery. Histologically the adventitia of the baroreceptor field is characterized by (1) an increased thickness and by less well developed elastic lamellae in comparison with other parts of the arterial wall, (2) a profuse blood and nerve supply, and (3) a richness of cellular elements. The presumptive baroreceptor terminals are localized in the inner 1/3 of the adventitia and display local enlargements that appear to show preferential association with the cell body or processes of the Schwann cell but not with other components of the adventitia. the enlargements are characterized by an accumulation of very densely packed mitochondria, and glycogen particles. No morphological alterations were noted in the baroreceptor terminals of SHR except for proliferated basal laminae that invest the terminals. Our work does not support the concept that resetting of the baroreceptors is due to degeneration of the terminals.

Animals↗
PubMed1980

Brain aging in normotensive and hypertensive strains of rats. II. Ultrastructural changes in neurons and glia.

A variety of age-related changes occur in the structure of neurons in the cerebral cortex of Wistar-Kyoto and spontaneously hypertensive rats. The most marked alteration associated with increasing age was the deposition of lipofuscin pigment, primarily at the bases of apical dendrites of pyramidal neurons. While no strain-related differences in the amount of lipofuscin pigment were observed in the youngest (3 months) and in the aged (22-27 months) groups of rats, it appeared that hypertensive rats had larger pigment deposits at 12 months of age. At the ultrastructural level, neurons of the aged brains exhibited numerous nuclear invaginations and filamentous nuclear inclusions, increased amounts of Golgi complex and two types of cytoplasmic inclusions. The number of degenerative structures in the neuropil (membranous whorls, dystrophic axons and alterations in myelin sheaths) was also apparently increased in the aged brains. Neurofibrillary tangles were observed in dendritic processes of a 27-month-old Wistar-Kyoto rat. Glial cells accumulated distinctive pigment granules by which the three types of glia could be identified.

Age Factors↗
PubMed1980

Effects of aging on the structural and permeability characteristics of cerebrovasculature in normotensive and hypertensive strains of rats.

This study demonstrates that markedly different patterns of age-related changes in blood pressure and body weight occur among normotensive Wistar-Kyoto (WKY) and Sprague-Dawley (SD) rats and spontaneously hypertensive rats (SHR). In addition, a variety of age-related structural alterations occurred in the walls of arterioles, capillaries, and venules of the frontal cortex. These changes include: (1) an increase in the thickness of the vascular wall by deposits of collagen and basal lamina which, in some cases, extended into the surrounding neuropil; (2) the presence of a flocculent material in the adventitia of intracerebral arterioles; (3) vesicular inclusions in perivascular macrophages, pericytes and smooth muscle cells which were labelled with i.v. administered horseradish peroxidase (HRP); (4) fragmentation of smooth muscle cells; and (5) accumulation of lipofuscin-like pigments in perivascular glial processes. The hypertensive rats exhibited these changes, but they were more advanced and more widely distributed throughout the cerebral cortex. The aged hypertensive rats occasionally had large bundles of 10 nm diameter, intermediate filaments in the endothelial cells. Whereas no change in blood-brain barrier permeability to HRP was observed in the aged normotensive rats, all age groups of the hypertensive rats exhibited increased permeability to HRP in the initial segment of penetrating arterioles in laminae I and II of the cerebral cortex.

Age Factors↗
PubMed1977

Stability of the intra-epithelial component of the blood-testis barrier in epinephrine-induced testicular degeneration in Syrian hamsters.

Adult male Syrian hamsters were given daily intraperitoneal injections of epinephrine (1.0 mg/kg) and papaverine, a vasodilator, (60 mg/kg) for a period of ten days. After the treatment period, lanthanum and horseradish peroxidase tracer studies were used to examine the intra-epithelial component of the blood-testis barrier. Degenerating tubules often exhibited only Sertoli cells and spermatogonia, or Sertoli cells alone. Sertoli cell processes in the degenerating tubules often arched out from the main cell body to make contact with other Sertoli cell processes, forming a series of vacuole-like spaces in the germinal epithelium, adluminal to the Sertoli-Sertoli junctions. At the site of contact between these arching Sertoli cell processes one to eight tight junctions had formed with hexagonal arrays of Sertoli cell cytoplasmic filaments located immediately adjacent to these junctions. Cisternae of the Sertoli cell endoplasmic reticulum lay deep to the layer of cytoplasmic filaments. It appeared that these junctions had originated after the expulsion of the germinal elements of the seminiferous epithelium. Penetration of the tracers in the degenerating seminiferous tubules was prevented by what appeared to be normal Sertoli-Sertoli junctions located between apposed Sertoli cells, adluminal to the remaining spermatogonia when these resisted degeneration, or just adluminal to the basal lamina in those tubules in which spermatogonia were absent.

Animals↗
PubMed1976

Light and electron microscopic localization of ATPase in normal and degenerating testes of Syrian hamsters.

The distribution of Mg++-activated ATPase was determined with light and electron microscopy in normal and degenerating seminferous tubules. In the normal animals ATPase was localized in the interface between spermatids and Sertoli cells, in association with the cytoplasmic filaments contained within Sertoli cell processes, and in the lymphatic endothelium. ATPase activity increased in degenerating tubules as observed by light microscopy. Electron microscopic investigations of the degenerating tubules which contained only spermatogonia and Sertoli cells revealed reaction product on the outer surface of the Sertoli cell processes and within the interface between adjacent Sertoli cells. Reactaction product was also observed in the Sertoli cell processes between the cytoplasmic filaments and the cell membrane. Where filaments were absent in Sertoli cell processes, no reaction product was observed. These electron microscopic studies indicate that the increase in ATPase activity in testicular degeneration is probably a relative increase due to a loss of the germinal elements of the tubular epithelium and subsequent apposition of the Sertoli cell processes. We speculate that the ATPase activity localized within the Sertoli cell processes may be involved in providing an energy source for filament motility.

Adenosine Triphosphatases↗
PubMed1975

Light, fluorescence and electron microscopic studies of rabbit subclavian glomera.

The subclavian glomera (aortic bodies) of young New Zealand white rabbits were studied with the light, fluorescence, and electron microscopes. Two cell types were identified: type I, granule-containing (chief) cells, and type II, agranular (sustentacular) cells. The type I cells possessed large nuclei, the normal complement of cytoplasmic organelles and numerous electron-opaque cytoplasmic granules. The type II cells were agranular with attenuated cytoplasmic processes which partially or completely ensheathed the type I cells. The glomera were well vascularized. Capillary endothelial cells contained numerous pinocytotic vesicles, but few fenestrae. Two profiles of nerve terminals were observed. One, apposing the type I cells, contained numerous electron-lucent vesicles, several dense-cored vesicles, mitochondria and possessed membrane specializations resembling those usually observed in synaptic zones. The other profile contained abundant mitochondria and a few electron-lucent and dense-cored vesicles. Structural specializations were not observed on the apposed membranes of these terminals or adjacent to type II cells. Fluorescence histochemistry revealed an intense yellow-green fluorescence in the glomera, which indicated the presence of biogenic amines, possibly primary catecholamines or an indolamine. The electron-opaque granules observed in the type I cells were believed to be the storage sites for these amines. The subclavian glomera were found to be morphologically similar to the carotid body which is a known chemoreceptor.

Animals↗
PubMed1975

An electron microscopic study on the effects of reserpine on the subclavian glomera of the rabbit.

Young male and female New Zealand white rabbits were given a daily subcutaneous injection of reserpine (Serpasil, Ciba; 3 mg/kg) for two days and were sacrificed 24 hours after the last injection. The subclavian glomera (aortic bodies) were processed for electron microscopy to determine the effects of this biogenic amine depleting agent on the electron-opaque cytoplasmic granules of the parenchymal type I cells. Observations of glutaraldehyde-osmium tetroxide fixed glomera from reserpinized animals showed a slight decrease in granule density of the type I cells. Glomera fixed in glutaraldehyde and incubated in potassium dichromate (pH 4.1) demonstrated a reduction in granule opacity following reserpine treatment. Control glomera incubated in potassium dichromate displayed electron-opaque granules. These results indicate that reserpine does deplete the amines without granule disappearance or changes in granule population. The positive reaction of the control tissue granules to potassium dichromate incubation suggests that the predominant biogenic amines in the electron-opaque granules are unsubstituted monoamines. Persistence of the opaque granules following reserpinization and glutaraldehyde-osmium tetroxide double fixation, may be due to amine-binding protein within the granules. The mode of granule depletion could not be ascertained with certainty.

Animals↗
PubMed1975

The fine structure and phosphatase cytochemistry of the golgi complex and associated structures in the sertoli cells of Syrian hamsters.

The Golgi complex in the Sertoli cell of the Syrian hamster is well developed and consists of stacks of cisternae and associated vesicles. The inner- and outermost cisternae of the Golgi stacks are usually moderately dilated and exhibit numerous fenestrations. The middle portions of the intermediate cisternae are greatly flattened and not fenestrated, but toward the periphery these cisternae gradually become dilated and show a few fenestrations. On the inner aspect of the Golgi stacks the following structures are seen frequently: (1) one or two series of linearly arrayed circular profiles some of which are interconnected by tubules; (2) networks of anastomosing tubules with circular or oval meshes (800 to 1200 A in diameter); and/or (3) irregularly disposed tubules. The circular profiles and tubules are approximately 450 A in diameter. Acid phosphatase activity was localized in these anastomosing tubules when the tissues were incubated for more than one hour in a modified Gomori's medium (Barka and Anderson, 1963). Strong thiamine pyrophosphatase activity was demonstrated in the inner one to three cisternae of the Golgi stacks but not in the associated tubules. The system of the Golgi associated tubules is morphologically and histochemically distinct from the Golgi stacks and is probably equivalent to the Golgi-endoplasmic reticulum-lysosome system (GERL) in other cell types. The three dimensional aspects of the GERL-equivalent system are discussed.

Acid Phosphatase↗
PubMed1975

A glutaraldehyde/potassium dichromate tracing method for the localization and preservation of abdominal extra-adrenal chromaffin tissues.

The present work introduces a method for the localization in situ of the abdominal paraganglia. After treating retroperitoneal tissue blocks with a near-neutral glutaraldehyde/potassium dichromate solution following routine glutaraldehyde perfusion, intra- and extraadrenal chromaffin tissues develop a pronounced brown color from the interaction of glutaraldehyde/potassium dichromate with amines. In this manner, visualization of the abdominal extra-adrenal chromaffin organs is enhanced at the same time that cellular ultrastructure is preserved. Subsequent examination of the dichromate-reacted tissues with the electron microscope confirms that they represent the amine-rich paraganglia. This method offers an effective alternative to extensive sampling of plastic-embedded blocks for localizing peripheral chromaffin tissue and has been used to define the exact distribution of abdominal paraganglia in the rabbit.

Abdomen↗