Pear-shaped Body Research Articles

THE CRIOLLO SHEEP IN PERU

SUMMARYThere are approximately ffteen million sheep in Peru, with more than 50% of this population being located in peasant communities and considered to be Criollo. Sheep were introduced by the Spanish, producing an almost complete displacement of the native camelid population. These animals were the foundation of the Criollo sheep presently found in the peasant communities of the Peruvian Andes. The Criollo sheep has a typically pear-shaped body, with a relatively small head, most often with horns. Productive characteristics among the Criollo sheep in the sierra are highly variable and depend mainly on the locations where they were raised. Criollo sheep andtheir crosses with improved breeds show a higher survival rate than crosses among the improved breeds of sheepin Peru. This indicates that although not as productive in conventional terms (weaning weight or fleece production) the criollo are well adapted to their environment.

Effect of Cerophyl growth medium on exocytosis in Tetrahymena thermophila.

Culturing the ciliate Tetrahymena thermophila in Cerophyl has provided an opportunity for studying the assembly and/or synthesis of the intramembrane particle array, the rosette, which marks the site of exocytosis in these cells. Cultures grown in this medium cease cell division after only 12h and enter 'stationary phase' earlier (12h of growth) relative to growth in standard medium (proteose peptone). In addition, the cell changes from the normally observed pear-shaped body to a thinner more ellipsoid form. Despite the initial similarities to starving cells, several differences are observed in the Cerophyl-grown cells. One is that cell size remains constant for at least 72h in contrast to starved cells. Secondly, in spite of this block in cell division, results from freeze-fracture replicas of the cell membrane of these cells show that they continue to assemble rosettes, the number of which increases approximately six times, from 0.34 rosette/microgram2 to 2.1 rosettes/microgram2. Addition of the protein synthesis inhibitor, cycloheximide (6h exposure), during growth in Cerophyl shows that 70% of rosettes can be assembled, despite the blockage of translation, by using pre-existing component(s) from a pool. The remaining 30% must involve de novo synthesis of one or more components; this percentage can be increased with longer exposure to the drug. Thirdly, an apparent increase in the number of mucocysts is observed by thin-section electron microscopy. At first (12-24h) only docked mucocysts seem to accumulate in the cell. However, by 36h a considerable increase seems to have taken place, particularly in the number of mucocysts located in the cytoplasm. In the cycloheximide-treated cells this increase in mucocysts begins to be blocked after 6h of exposure to the drug. These observations are in agreement with the results obtained from the freeze-fracture data on the concomitant increase in number of rosettes. This system therefore offers the first possibility of exploring the biosynthesis of these components.

Morphologie und Infraciliatur von Perispira pyriformis nov. spec., Cranotheridium foliosus ( Foissner, 1983) nov. comb. und Dileptus anser ( O. F. Müller, 1786) (Protozoa, Ciliophora)

Summary The morphology and the infraciliature of Perispira pyriformis nov. spec., Cranotheridium foliosus ( Foissner , 1983) nov. comb., and Dileptus anser Muller , 1786 are described from small alpine water bodies. Perispira pyriformis differs from known species of this genus by its marked pear-shaped body. The infraciliature consists of approximately 19 somatic kineties, 1 perioral kinety with paired basal bodies and a dorsal brush of 3 rows. The spiraling oral bulge may be derived from the straight oral bulge of Spathidium . This is supported by the observation that nematodesmata occur only in the anterior part of the oral bulge. Cranotheridium foliosus differs from the other species of this genus by its body shape and the nuclear apparatus. The infraciliature consists of about 25 somatic kineties and 1 perioral kinety with paired basal bodies from which very delicate nematodesmata originate. The dorsal brush is composed of several short rows at the left lateral side and 3 longer rows at the dorsal side. Perispira pyriformis and Cranotheridium foliosus have the peculiarities of the Spathidiidae and can be classified without difficulty into this family. Dileptus cygnus Claparede and Lachmann , 1859 is synonym with Vibrio anser O. F. Muller , 1786 (compare Dingfelder 1962). It is characterized by the conspicuous long and contractile proboscis and numerous contractile vacuoles extending to the top of the proboscis. The strongly varible number of the somatic kineties in different populations (see Grain and Golinska 1969) suggests the occurrence of presently inseparable sibling species.

The Weissenberg effect in molten polymers

The climb of viscoelastic liquids up a rotating rod, often called the Weissenberg effect, has often been observed in polymer solutions, and several theoretical analyses of this phenomenon have been published. However, no observations of rod-climbing in polymer melts have been reported. In the present work, three commercial polyethylenes were melted in a special chamber under a controlled atmosphere, and a rod was rotated in the pool of molten polymer. The behavior of the free surface was noted as a function of time and rotational speed. In the case of the resin with the lowest molecular weight and the highest density, the free surface reached a steady-state shape within seconds of changing the rotational speed. For the other two resins, the development of the shape of the free surface took place over periods of the order of one hour or more. In the cases where the starting transient was very long-lasting, the melt first climbed the rod and accumulated in a large bulge. Then, the fluid in the bulge flowed down to the bottom of the raised column and a pear-shaped body of liquid was formed whose shape continued to undergo gradual change for periods up to several hours. At high speeds, inertial effects destabilized the flow and led to asymmetry and time unsteadiness in the shape of the raised body of liquid.

Die Feinstruktur des Epithels des Ductus pancreaticus major des Schafes

Light-and electron-microscopic and some histochemical investigations on the epithelium or the ductus pancreaticus major were carried out in sheep. At least six different cell types are recognizable: (1) nondifferentiated duct cells; (2) cells containing apical secretory granules; (3) goblet cells; the mucosubstances of type 2 and 3 are PAS- and Alcian-blue-positive, also reacting wih methenamine silver; (4) ciliated cells, containing a single cilium with the microtubular pattern 9+2; (5) tuft cells with extremely long and wide microvilli and a pear-shaped cell body; (6) migrating cells, mainly lymphocytes and some assumed eosinophils, showing reaction to Mg++-activated ATPase.

Jamdat Nasr fund fra Oman

Jamdat Nasr fund fra Oman

Structure of the Sucker of Echeneis

A CENTURY ago Gunther1 stated thus: “There is scarcely a fish of the existence of which the ancients have been equally certain and which has so much occupied their imagination—from a power thought to be inherent in the creature to counteract the strongest physical agencies—as the Echeneis of the Greeks or the Remora of the Latins”. This was followed in 1918 by Gudger2, who called it “The most interesting of the marine fishes not merely from the popular but even more from the scientific point of view”. He, however, could not reconcile himself to the view that the fish could exert enormous pressure, and accepting Ekman's “deadwater theory” said “Another myth of the ancients is dissipated in thin air”. Norman3 describes the sucker as being a highly specialized structure but goes no further. I have directed attention4 to the presence of a pear-shaped body, the pyriboss, and a chamber in front of it, and the possibility that the plates are lowered rather than raised adhering. Mention is made of the pyriboss as “a curious round ossification” and the chamber as “a notch at the posterior extremity” by Storms5.

TUMORS OF THE PINEAL BODY

Tumors of the pineal body are rare, and their symptoms often vague. Like hypophyseal tumors, pineal (or epiphyseal) tumors, may give the general symptoms of brain tumor, with certain focal signs, and in addition, by interfering with physiological function, may bring about distinct and characteristic disturbances in nutrition. When these two separate and distinct classes of symptoms, namely, the neurological and metabolic, are present, the diagnosis becomes reasonably certain and operative removal becomes a possibility. The pineal body arises from a diverticulum of the roof of the third ventricle. As seen in the 3 to 4 months' embryo, it is a pear-shaped body, which in section shows a number of radiating compartments (lobuli), containing the parenchyma of the gland, irregularly separated by connective-tissue and vessels, which sink in from a connective-tissue capsule. Its connections with the rest of the mid-brain are extremely difficult to trace out, especially the

Meteors

LAST Friday evening (October 19) we in Aberyst with saw a very beautiful meteor. It was ten minutes past six in the evening, when as I was walking along the shore and looking seaward (west), I saw the meteor rapidly descending as a pear-shaped body of red, yellow, and purple light, increasing much in brightness till it reached about twenty feet, as it looked, from the sea surface, when it suddenly and completely disappeared. Its track seemed a part of it—a tail to it—being at first a pale golden light continuous with the body of the meteor below, extending vertically up and ending rather abruptly above.