Histochemistry of the parenchyma of Cysticercus bovis.

The contents of mucosubstances, proteins and lipids, and the activity of several enzymes were studied in the parenchyma of the bladder wall and the invaginated portion of Cysticercus bovis aged 108 days. The parenchyma of both parts contained a large amount of glycogen and minute bodies with a high activity of acid phosphatase and non-specific esterase. By contrast to older larvae, the young larvae contained a minute amount of hydrophobic lipids. The rostellum was developed and similar to the suckers contained glycogen.     

Tissue reaction to Cysticercus bovis in the lung of artificially infected cattle

The tissue reaction to Cysticercus bovis in the lung of cattle with an experimental infection was an inflammatory rim originating in the immediate vicinity of the cysts. The cysts recovered at days 83 and 102 p.i. contained living cysticerci. The rim was composed either of a layer of high histiocytes organized in palisades (at day 83 p.i.), or a lyer of flat histiocytes (at day 102 p.i.). The outer layer of the rim consisted of fibroblasts, reticular cells and a different number of eosinophil- and neutrophil luekocytes. On the periphery, the rim was formed by granulation tissue infiltrated with lymphoplasmocytes. At the border between the layers of the inflammatory rim there were conspicuous foci of a necrotic appearance typical of a tissue reaction to C. bovis.     

Morphological and histochemical demonstration of hooks in the rostellar region of Cysticercus bovis.

Hooklets and early developmental stages of hooks were discovered in the tegument among the microtriches in the rostellar region of 83- and 108-day-old Cysticercus bovis. The cortical layer of hooks consists of proteins with tyrosine and SS groups. The rostellar sac and bulb are distinctly developed in the parenchyma of the rostellar region.     

Morphological determination of the age of Cysticercus bovis in very young calves with cysticercosis.

Characteristics and measurements are given for early developmental stages of Cysticercus bovis. The data emerging from our study indicate that the age of a one to two month-old larva from a spontaneous infection can reliably be determined in histological sections. On these grounds we have been able to determine that the cysticercus infection in the two calves (aged 21 and 27 days respectively) had been acquired prenatally.     

Tissue reaction in the heart of cattle with a spontaneous and artificial Cysticercus bovis infection.

Results of detailed studies on tissue reactions to Cysticercus bovis in the heart of cattle, together with a comparison of findings in animals with spontaneous and experimental infection, and an evaluation of tissue reactions in relation to the location, morphology and morphogenesis of C. bovis provided evidence for the fact that in general, the response of the heart to the presence of C. bovis was an inflammatory reaction characterized by the origin of a pseudoepithelial border and a zone of granulation tissue. Later, when necrotic changes started to affect the cysticercus, the inflammatory reaction started to develop anew. It was accompanied by an exudation and a subsequent resorption. Characteristic features were focal necroses both of the exudate and the inflammatory border followed by a dystrophic calcification, focal necroses and a dystrophic calcification of individual collagenous fibres and groups of these fibres in addition to a regular appearance of necrotic-like foci typical of a reaction to C. bovis. The location of the cysticercus in a certain part of the lymphatic system of the heart and in skeletal muscles was shown to have a considerable effect on the course of the inflammatory reaction. Differences in the development of the inflammatory reaction explained concomitant findings of dead and live cysticerci at the same time after an experimental infection.     

Pathology of experimental Cysticercus bovis infection in the reindeer (Rangifer tarandus Linné, 1758)

In the present study, the tissue reaction of the brain, skeletal muscles and heart in experimental C. bovis infection of the reindeer is described. There is non-purulent cysticercal leptomeningites with formation of multinucleate symplasms in the cerebral meninges, and lymphocytic encephalitis in the superficial layers of the cerebral cortex. The tissue reaction around the morphologically differentiated cysticercus in the meningeal location is similar to that in muscle cysticercosis of cattle. In muscles and heart, larvae die very soon after infection and they are resorbed in the course of formation of fibroplastic granulation tissue around them. C. bovis reaches the infective stage in cerebral localization only. The authors suppose that this phenomenon is due to a certain degree of immunological tolerance in the brain.     

Histochemistry of the racemose form of Cysticercus cellulosae.

The racemose form of brain cysticercosis arises from an intense proliferation of the bladder wall after the scolex part has degenerated. The proliferating zones are 2-3 times thicker than the remaining parts of the bladder and are characterized by a densely folded tegument and thick subtegumental and parenchymal layers. The tegument and subtegumental cells contain a large amount of acid mucosubstances with sulpho groups and hydrophilic lipids, and exhibit a high activity of alkaline and acid phosphatases. The parenchyma contains a large amount of glycogen. With the gradual aging of the bladder wall and with the first signs of autolysis, the enzymatic activity as well as the amounts of glycogen, neutral and acid mucosubstances, and proteins decrease, and the hydrophobic lipids prevail over the hydrophilic ones. The results obtained are important for the differential diagnostics of cestode larval stages in the human brain.     

Ultrastructural study of the glandular system and its participation in tegument formation in Echinostoma revolutum cercaria

Six types of gland cells occurring in the body of developing Echinostoma revolutum cercaria are described at ultrastructural level. Three types of the gland cells, lateral, ventral and dorsal, release their secretion into the tegument of cercaria during its development in the media. Another three types, paraoesophageal, penetration and proper cytogenic gland cells are preserved in the body of the free-swimming cercaria. The paraoesophageal gland cells open on the tegument surface. Secretory granules of all types of gland cells and stratification of the body tegument arising by gradual release of the contents of the above mentioned three types of gland cells are characterized in detail.     

Histochemistry and fine structure of the bladder tegument of a larval Multiceps endothoracicus

Certain differences were found in the histochemistry and fine structure of an active bladder tegument of an infective larva of M. endothoracicus and a regressively changing bladder of an aging larva of this species. The bladder tegument of an aging larva contained an accumulation of acid mucosubstances and phospholipids, that of a younger larva neutral mucosubstances, and it reacted less strongly than the former to tyrosine, cystine and tryptophane. Evidence was obtained with the scanning (SEM) and transmission (TEM) microscope for regressive changes in the bladder of an aging larva: its microtriches were more slender, less tightly packed and fibrously interconnected, and there were spherical formations adhering to the microthrix border. Sometimes, the vacuolation of rod-shaped bodies was so much advanced that these bodies looked like vacuoles arising to the surface of the distal cytoplasm. Another sign of bladder regression was the formation of vacuoles in the cytoplasm of subtegumental cells with contents of a granular to crystalline structure.     

Ultrastructure of the forebody and foregut tegument and eccrine gland cells of Crepidostomum metoecus (Trematoda: Digenea: Allocreadiidae)

The forebody and foregut of Crepidostomum metoecus Braun, 1900 are invested with a tegument bearing regularly arranged surface tubercles comparable with the aspidogastrean surface structures. The tegument of the ventrolateral lobes and of the prepharynx is penetrated by ducts of eccrine gland cells. The frontal and prepharyngeal gland cells, localised in the parenchyma, discharge electron-dense granules. Their ducts are lined by peripheral microtubules and fixed to the tegument plasmalemma by a septate junction. The functional roles of these glands are discussed.     

On the regularities of distribution of Hypoderma bovis De Geer larvae parasitizing cattle herds in different parts of the range of this warble fly.

The type and parameters of the distribution of the second and third instar larvae of Hypoderma bovis in cattle herds in Czechoslovakia (54 herds, 7233 head), Mongolia (20 herds, 1809 head) and the USSR (48 herds, 4978 head) were studied. A statistical analysis showed a) that in the majority of cases negative binomial distribution serves as a model of the distribution of larvae with sufficient reliability; b) that the regularity of dependence of the distribution exponent k of the negative binomial distribution on the incidence of infestation remains constant in different parts of the range of this warble fly. The latter fact indicates that the regulatory systems limiting the population numbers of this warble fly are associated with host-parasite relationships and do not depend on a complex of conditions specific for various natural zones. In order to understand the regulatory processes in parasite populations it is necessary to study equally the regulatory mechanisms operating primarily on the level of specimens as well as the regulatory systems operating on the level of populations.     

Phytophthora ramorum: the situation in Scotland1

In Scotland inspections for Phytophthora ramorum on plants in the horticulture nursery trade started in July 2001 and are currently carried out four times per year. In addition, approximately 130 established gardens have been inspected for the disease during the years 2003 and 2004. Phytophthora ramorum has been found on Rhododendron, Viburnum, and lilac (Syringa vulgaris); the most important host plant is Viburnum tinus. The pathogen is confined to nurseries and garden centres with the exception of one private garden. The first finding was in April 2002 with 17 more outbreaks the same year. Since then the number of outbreaks per year has declined dramatically to 6 in 2003, 5 in 2004 and 3 until November 2005. Altogether, there have been 21 different outbreaks sites since the first finding, some with repeated occurrences of the disease.     

Pesticide residues: Food surveys in the United Kingdom

The development of food surveys for levels of pesticide residues, toxic metals and polychlorobiphenyls and related compounds is outlined. The role of the surveys in monitoring the effect on the levels of compounds in specific foods following changes in pesticide usage is explained. Studies over 8 years on levels in the total diet show they are well below the acceptable daily intakes recommended by the Food and Agriculture Organisation/World Health Organisation for organchlorine and other pesticides. During this period the levels found have in general declined.     

Rodents in the Tropics: Their Effects and Control

Abstract

Twenty four varieties of cowpea were evaluated for field resistance to Aphis craccivora Koch under natural infestation at Ile‐lfe, Nigeria. The varieties EW/1, TVu 1037, TVu 2896, TVu 2994 and TVu 3000 showed the lowest field infestation. This may be explained by antixenosis with respect to varietal selection or feeding and antibiosis. Screenhouse studies showed that the mechanism of resistance in TVu 1037, TVu 2896 and TVu 3000 includes antibiosis, manifested as high mortality of nymphs, reduced lifespan and low fecundity of adults.     

Bacterial canker on kiwifruit in Italy: anatomical changes in the wood and in the primary infection sites

The bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae is a severe threat to kiwifruit production worldwide. Many aspects of P. syringae pv. actinidiae biology and epidemiology still require in-depth investigation. The infection by and spread of P. syringae pv. actinidiae in xylem and phloem was investigated by carrying out artificial inoculation experiments with histological and dendrochronological analyses of naturally diseased plants in Italy. We found that the bacterium can infect host plants by entering natural openings and lesions. In naturally infected kiwifruit plants, P. syringae pv. actinidiae is present in the lenticels as well as in the dead phloem tissue beneath the lenticels, surrounded by a lesion in the periderm which appears to indicate the importance of lenticels to kiwifruit infection. Biofilm formation was observed outside and inside plants. In cases of advanced stages of P. syringae pv. actinidiae infection, neuroses of the phloem occur, which are followed by cambial dieback and most likely by infection of the xylem. Anatomical changes in wood such as reduced ring width, a drastic reduction in vessel size, and the presence of tyloses were observed within several infected sites. In the field, these changes occur only a year after the first leaf symptoms are observed suggesting a significant time lapse between primary and secondary symptoms. It was possible to study the temporal development of P. syringae pv. actinidiae-induced cambial dieback by applying dendrochronology methods which revealed that cambial dieback occurs only during the growing season.