Stellate Structure Research Articles

A critical velocity interaction between fast barium and strontium atoms and the terrestrial ionospheric plasma

A disk of barium and strontium vapor traveling radially outward, perpendicular to the geomagnetic field lines, may be created by the detonation of a high-explosive, radially shaped charge with a liner composed of the two metals in the upper atmosphere. Because of solar radiation resonance, both the barium and the strontium may be optically tracked. Observations indicate the early formation of the metal ions thus evolved into a disk-shaped, stellate structure with a dark hole at the center of a radial structure. The results of these experiments indicate that the process could occur on a cosmic scale, and that unconfirmed aspects of the theory relating to this process could be determined through variation of the parameters in future radial rocket experiments.

Peroxidatic activity of catalase in the sea urchin ovary.

Endogenous catalase activity in the ovary of two sea urchin species, Hemicentrotus pulcherrimus and Anthocidalis crassispina, was investigated by 3, 3′-diaminobenzidine (DAB) method.Osmicated DAB products were located at the lamellar (in H. pulherrimus) or stellate (in A. crassispina) structure of the cortical granule (Cg) in the mature egg and that of the presumptive cortical granule (pCg) in the oocyte.As for the A-type giant granule (A-g.) in the nurse cell, the same product was also found at the cortical granule-like structure (Cgls), but not at the other part of A-g.. In the present study of sea urchin ovary it is clear that the A-g. is “Heterophagosome”, and that the heterophagic substance may be regenerated as a nutrient for the growing oocyte after autolysis of nurse cell.

Tendril and glomerular collaterals of climbing fibers in the granular layer of the rat's cerebellar cortex.

Rapid Golgi preparations show that two kinds of collaterals issue from the climbing fiber in its course through the granular layer. The first resembles the tendrils found in the molecular layer and consists of globose varcosities connected by a very fine thread. In electron micrographs these varicosities in the granular layer contain dense aggregates of round synaptic vesicles at least 520 A in diameter and the connecting threads contain numerous microtubules. The varicosities synapse on the somata of Golgi II cells and on the shafts of dendrites belonging to both Golgi II and granule cells. The second type of collateral emerges from the main stem of the climbing fiber as a stout branch that sprays out abruptly into a large efflorescence. In electron micrographs this terminal appears as the central stellate structure in a glomerulus and is packed with round synaptic vesicles like those in the tendril varicosities. Granule cell dendrites encircle the terminal and occasionally synapse with it. Often the terminal in the glomerulus also forms an extensive junction—a synapse en marron—with the some of Golgi II cell. In this region the surface of the cell is wrinkled like a Spanish chestnut and the glomerular terminal is reciprocally ridged and furrowed to match. Synaptic complexes occur only in the furrows of the cell surface. A broad subsynaptic zone is filled with a fine filamentous matrix. This study provides the first morphological identification and description of climbing fiber terminations in the granular layer, the existence of which has been suggested by earlier Golgi studies and postulated by neurophysiologists. The fact that climbing fibers synapse on both granule cells and Golgi II cells complicates the analysis of the way in which the cerebellar cortex operates, because these two cells have postsynaptic effects of opposite sign. The climbing fiber is known to evoke a complex discharge from the Purkinje cell, consisting of a large primary spike and smaller secondary potentials. It is suggested that when a climbing fiber volley traverses the granular layer, the granule cells on which it synapses are induced to excite stellate and basket cells in the molecular layer which in their turn inhibit the secondary spikes of the climbing fiber response in the Purkinje cell. Meanwhile the Golgi II cells, stimulated by the same climbing fiber volley, suppress the granule cells and thus transsynaptically limit the duration of the inhibitory effects exerted by the interneurons in the molecular layer.

A Unique Stellate Plant Hair on Human Skin

An unusual stellate structure has been noted in the skin scrapings of diseased and nondiseased skin. It has a thick potassium hydroxide-resistant wall suggestive of cellulose. Its morphology is that of the stellate pubescence found on the leaves and stems of viburnum dentatum, arrowwood, an abundant deciduous plant that grows over much of the United States and Canada. We hope this report will familiarize both the dermatologist and the pathologist with this distinctive skin and slide contaminant of plant origin.

The ameloblastomatous potentiality of odontogenic epithelium demonstrated in tissue culture

Histologically, the ameloblastoma may show all of the structures normally seen in odontogenic epithelium, but a single biopsy specimen illustrates only a given static phase in the process of neoplasia. Tissue culture studies of rat embryo tooth buds demonstrated epithelial proliferation from the borders of odontogenic epithelium and the formation of lamellar-like structure observed in ameloblastomas. Later, the tooth buds grown in vitro showed formation of stellate reticulum-like structure in the epithelial outgrowths and formation of microcysts characteristic of ameloblastomas. Dissected epithelial outgrowths recultivated in vitro showed similar changes. These studies offer additional experimental evidence that ameloblastomas originate from epithelium with odontogenic potentiality.

On some Bivalve Entomostraca, chiefly Cypridinidæ, of the Carboniferous Formations

On some Bivalve Entomostraca, chiefly Cypridinidæ, of the Carboniferous Formations