Studies on the contractility of follicular wall with special reference to the mechanism of ovulation in hens

1. To investigate the mechanism of ovulation in the hen, histological and physiological investigations on the contractility of the follicular wall were carried out.

2. Smooth muscle bundles in the loose connective tissue coat from the stalk to the equator showed spontaneous rhythmic contractions with an alternation of contraction and pausing periods of about 4 min. The administration of prostaglandins F_2α (PGF_2α), E₂ (PGE₂), ovarian oviposition inducing factor (OOIF), oxytocin and acetylcholine increased the frequency and amplitude of the contractions.

3. The theca layer showed spontaneous contractions at a frequency of about 30 per 10 min. PGF_2α, OOIF, acetylcholine, adrenaline and noradren‐aline induced tonic contractions, whereas PGE₂, oxytocin and histamine induced relaxation.

4. It is suggested that the contraction of the follicular wall promotes the rupture of the stigma at ovulation and the neurotransmitters as well as prostaglandins and OOIF may be involved in this event.     

Features of follicular dendritic cells in ovine pharyngeal tonsil: an in vivo and in vitro study in the context of scrapie pathogenesis

Although the alimentary tract has been suggested as the most likely portal of entry in natural scrapie, a growing amount of data indicates that the respiratory system and more specifically the pharyngeal tonsils serve as a natural portal of entry for scrapie. This study describes for the first time the broad cell populations in the lymphoid compartment of pharyngeal tonsils and more specifically inside the lymphoid follicles where the scrapie agent accumulates during the period of latency. Follicular dendritic cells (FDCs), stromal cells located in the light zone of the germinal centre of lymphoid follicles, seem to be the principal causal factor in the accumulation of the infectious agent in transmissible spongiform encephalopathy (TSE) diseases. Knowing that efficient lymphoreticular prion propagation requires PrPc expression, we analysed the expression of PrPc with the mouse monoclonal antibody Pri 909 both in situ and on FDC-cluster-enriched cell suspensions. In situ, a positive staining was observed in the germinal centre of pharyngeal lymph follicles. The germinal centre labelling was due to the presence of a follicular dendritic network as revealed after immunogold staining of isolated FDC clusters. Our results suggest that the pharyngeal lymphoreticular system and more specifically PrPc expressing follicular dendritic cells could serve as a prion "reservoir" during the latency phase, thus playing a key role during the scrapie lymphoinvasion.     

Cardiac output technologies with special reference to the horse

Critical illness, anesthesia, primary cardiovascular disease, and exercise may result in marked hemodynamic alterations. Measuring cardiac output (CO) is central to defining these alterations for both clinician and researcher. In the past 10 years, several new methods of measuring CO have been developed for the human medical market. Some of these methods are now validated in the horse and are in clinical use. The Fick method has been used in equine research for more than a century. It depends on simultaneous measurement of mixed venous (pulmonary arterial) and peripheral arterial oxygen content and oxygen uptake by the lungs. The technique is technically demanding, which restricts its clinical use. Indicator dilution techniques, with indocyanine green, cold (thermodilution), or lithium as the marker, have also been widely used in the horse. The indocyanine technique is cumbersome, and thermodilution requires right heart catheterization, which is not a benign procedure, making both of these methods less than ideal for clinical use. Lithium dilution requires catheterization of a peripheral artery and a jugular vein. It has recently been validated in anesthetized adult horses and neonatal foals. Doppler echocardiography is a noninvasive ultrasound-based technique. More accurate measurements are obtained with transesophageal than with transthoracic measurements; however, both methods require considerable technical expertise. Bioimpedance and pulse contour analysis are 2 new methods that have yet to be validated in the horse. With the currently available technology, lithium dilution appears to be the method of measuring CO best suited to the equine clinic.     

Intercalated duct cells in the chicken pancreatic islet with special reference to the alloxan administration.

The intercalated duct cells were observed in the A and B islets of the chicken pancreas. These cells adhered with each other by intercellular junctional complexes at the apical side. They had many microvilli projecting into the lumen. Abluminally, they displayed extended slender cytoplasmic processes between islet endocrine cells. Administration of alloxan resulted to denser cytoplasm and a more prominent thickening of cytoplasmic processes of the intercalated duct cells, although the blood glucose levels did not show appreciable changes by the treatment. The intercalated duct epithelial cells appeared clearly as stellate cells. The lysosomes increased in size and number with passage of time after alloxan administration. The present findings may suggest that intercalated ducts are not only anatomically important as a structure passing through the islet but also play physiologically by protecting the islet endocrine cells.     

Pathogenesis of experimental bovine spongiform encephalopathy: preclinical infectivity in tonsil and observations on the distribution of lingual tonsil in slaughtered cattle

The infectivity in tissues from cattle exposed orally to the agent of BSE was assayed by the intracerebral inoculation of cattle. In addition to the infectivity in the central nervous system and distal ileum at stages of pathogenesis previously indicated by mouse bioassay, traces of infectivity were found in the palatine tonsil of cattle killed 10 months after exposure. Because the infectivity may therefore be present throughout the tonsils in cattle infected with BSE, observations were made of the anatomical and histological distribution of lingual tonsil in the root of the tongue of cattle. Examinations of tongues derived from abattoirs in Britain and intended for human consumption showed that macroscopically identifiable tonsillar tissue was present in more than 75 per cent of them, and even in the tongues in which no visible tonsillar tissue remained, histological examination revealed lymphoid tissue in more than 90 per cent. Variations in the distribution of the lingual tonsil suggested that even after the most rigorous trimming of the root of the tongue, traces of tonsillar tissue may remain.     

FDC-B1: a new monoclonal antibody directed against bovine follicular dendritic cells

Follicular dendritic cells (FDCs) are a unique population of accessory cells located in the light zone of the germinal centres of lymphoid follicles. Their involvement in the generation of humoral immune responses implies a potential role for these cells in many disorders. Indeed, in prion diseases, FDCs seem to be the major sites of extraneuronal cellular prion protein expression and the principal sites of the infectious agent accumulation in lymphoid organs. The identification of FDC is useful for the analysis of their distribution in reactive lymphoid tissue as well as in pathological conditions. The production and characterisation of a new mouse monoclonal antibody directed against bovine follicular dendritic cells (FDC-B1) is reported. The antigen detected by FDC-B1 is expressed exclusively on the surface of FDCs in ruminant lymphoid organs. The antigen has an approximate molecular weight of 28 kDa.     

Ecological basis of parasite control: Trematodes with special reference to fascioliasis

In this paper the main ecological components of selected animal trematode infection cycles are considered with regard to the possibilities of control. The geographical distributions of Fasciola hepatica, F. gigantica, Paramphistomum microbothrium, Schistosoma bovis and S. mattheei are compared in relation to the distribution patterns of their snail intermediate hosts. In order to constitute an effective lifecycle host, intermediate host and the eggs and freeliving stages of the parasite overlap in the effective biotope. Comparing the biotopes of the different trematodiases it becomes evident that they have much in common particularly as the snail intermediate hosts occupy identical niches in a food-chain in which the pollution by the host species results in abundant food for the snail. Moreover, the physical activaties of herbivores, e.g. trampling down the turf, create favourable habitats for the intermediate host.The dynamic nature of the freshwater snail habitats characteristic for trematodiasis, regularly results in a complete disappearance of the effective biotopes in the field. With regard to the parasite these effects are overcome by a long life-expectancy of egg producing parasites in the host population. Small scale changes in availability of appropriate hosts for successful cercarial establishment are compensated by the extended period of cercarial shedding from the snail population.These features in combination with the survival of eggs and the grazing and drinking behaviour characteristics of the hosts tend to stabilize the potential oscillations in transmission rate. Because of the complicated nature of interdependency within the host-trematode-intermediate host complex, the ecological base with regard to practical measures is fundamentally wide. However, the pressure upon the situation by social and economic conditions limits operative possibilities considerably.     

Paratuberculosis with special reference to cattle. A review

Paratuberculosis is a chronic, granulomatous enteritis caused by Mycobacterium avium subspecies paratuberculosis affecting domestic and wild ruminants. The symptoms of clinical paratuberculosis are chronic diarrhoea and progressive weight loss while subclinically infected animals mainly have decreased production. The infection is widespread throughout the world and causes substantial financial losses for the farming industry. One of the major obstacles in the control of this disease, is the difficulty of identifying subclinically infected animals. This review gives a summary of several aspects of paratuberculosis including clinical importance, pathology, immunology and properties of the infectious agent. Special emphasis will be on the available diagnostic methods, their use and limitations.     

Salmon in New Zealand with special reference to the quinnat salmon

Of the 3 species of salmon successfully acclimatised in New Zealand, the quinnat, Oncorhynchus tshawytscha (Walbaum) is the most widespread. It is found mainly in the east coast rivers of the South Island. Although adults live in the sea and return to freshwater to breed, lake populations have developed either voluntarily or because egress to the sea is blocked by dams. Sea-living adult quinnat salmon return to rivers in summer to spawn in their natal streams and once in freshwater, cease feeding and the gut degenerates. Eggs laid by the females in redds are fertilised by the male, after which both parents die. Most young salmon emerging from the redds migrate downstream but their fate is uncertain. The few remaining feed and grow and migrate to sea in early summer. Examination of the ridges on fish scales reveals information about migration patterns which assists in studies conducted by the Ministry of Agriculture and Fisheries in the Glenariffe Stream. Marking and tagging of smelts is expected to provide information on survival to adult return and on movements of salmon at sea. The quinnat is the salmon species most favoured by anglers and it is also considered to have a commercial future in New Zealand, using the method of ocean ranching.     

Bovine mammary dendritic cells: a heterogeneous population, distinct from macrophages and similar in phenotype to afferent lymph veiled cells

Dendritic cells (DC) are a heterogeneous population of professional antigen presenting cells and are potent stimulators of na?ve T-cells. However, there is little previous research describing DC in bovine mammary tissue, primarily because of the difficulty distinguishing these cells from macrophages, which possess a similar phenotype. Using immunohistofluorescence and a combination of markers (MHC-II, CD205, CD11c), DC were localized in the bovine mammary gland and supramammary lymph node. In mammary tissue DC were found within the alveolar epithelium and within the intralobular connective tissue. In the lymph node DC were found on the periphery of B-cell areas, in the cortex, and among T-cells in the paracortex and medulla. DC in mammary parenchyma and supramammary lymph nodes were quantified and further characterized using flow cytometry. DC were CD11c(hi), CD14(lo) cells that expressed MHC-II and CD205. DC could be distinguished from macrophages based on their low CD14 expression. This research provides a better understanding of mammary gland immunology, while potentially aiding in the targeting of antigens to mucosal DC for vaccine development.     

Degenerative joint disease (osteoarthrosis): A review with special reference to the dog

Nomenclature, incidence, etiology, pathogenesis and morphological appearance of primary and secondary osteoarthrosis (osteoarthritis) are discussed. Differences and similarities between osteoarthrosis in man and the dog are mentioned. Primary osteoarthrosis occurs in the dog but secondary osteoarthrosis seems to be more frequent. In the dog hip dysplasia, Legg-Perthes' disease, osteochondritis dissecans of the shoulder and ununited anconeal process are conditions which, among others, give rise to osteoarthrosis. Changes in the knee caused by instability after rupture of the cruciate ligaments are not those of true osteoarthrosis. There is only minimal involvement of the joint cartilage in spite of osteophyte formation, thickening of the synovium and derangement of the menisci. Clinical signs in degenerative joint disease are usually insidious in onset. For a varying period of time they are as a rule not very conspicuous. In more advanced cases the cljnical manifestations are pain, limitation of movement and muscle atrophy. The underlying changes are cartilage destruction, subchondral sclerosis, osteophytes and thickening of the synovium. In very advanced cases in man there is even attrition of bone, which clinically leads to instability and subluxation. In human coxarthrosis cyst formations are frequently seen. Etiology and pathogenesis are obscure, or only partly understood, and in animals diagnosis is sometimes difficult. There is often poor correlation between severity of radiographic changes and clinical signs. Résumé. On examine la nomenclature, l'incidence, l'étiologie, la pathogénie et l'aspect morphologique de l'ostéo-arthrose (ostéo-arthrite) primaire et secondaire. On mentionne les différences et similitudes entre I'ostéo-arthrose rencontrée chez l'homme et chez le chien. L'ostéo-arthrose primaire se rencontre chez le chien, mais les cas d'ostéo-arthrose secondaire sont plus fréquents. Chez le chien, la dysplasie de la hanche, la maladie de Legg-Perthes, l'ostéochondrite disséquante de l'épaule et I'apophyse anconée disloquée sont des états qui, entre autres, engendrent l'ostéo-arthrose. Des transformations du genou, causées par une instabilité après rupture des ligaments croisés, ne sont pas celles de I'ostéo-arthrose proprement dite. Le rôle du cartilage articulaire n'est que minime, malgré l'apparition d'ostéophytes, l'épaississement des membranes synoviales et les troubles des ménisqua. Les signes cliniques des maladies articulaires dégéntratives sont généralement insidieux au départ. Pendant une période de temps variable, ils ne sont d'ordinaire pas très marqués. Pour les cas plus graves, les manifestations cliniques sont la douleur, la restriction des mouvements et l'atrophie musculaire. Les transformations qui sont à base de ces manifestations comprennent: destruction du cartilage, sclérose sous-cartilagineuse, ostéophytes et épaississement des membranes synoviales. Si chez l'homme, l'etat est très grave, on assiste même à l'attrition des os, qui, du point de vue clinique, mène à I'instabilité et la subluxation. En cas de coxarthrose chez l'homme, on observe fréquemment la formation de kystes. On ne connaît pas bien et ne comprend que partiellement l'étiologie et la pathogénie de ces maladies et, chez les animaux, le diagnostic est beaucoup plus difficile à établir. Très souvent on n'obtient pas de bonne corrélation entre I'importance des changements radiographiques et les signes cliniques. Zusammenfassung. Nomenklatur, Häufigkeit, Ätiologie, Pathogenese und morphologisches Aussehen von primärer und sekundärer Osteoarthrosis (Osteoarthritis) werden besprochen. Unterschiede und Ähnlichkeiten zwischen Osteoarthrosis des Menschen und des Hundes werden erwähnt. Primäre Osteoarthrosis tritt beim Hund auf, jedoch scheint die sekundäre Osteoarthrosis häufiger zu sein. Beim Hund sind Hüftendysplasie, Legg-Perthessche Krankheit, Osteochondritis dissecans der Schulter und unvereinigte anconeale Prozesse Zustände, die unter anderem zu Osteoarthrosis führen. Verändemngen am Knie, die durch Instabilität nach Ruptur der Kreuzbänder verursacht werden, sind nicht die echter Osteoarthrosis. Der Gelenkknorpel ist nur minimal betroffen, trotz Osteophytenbildung, Verdickung der Synovia und Meniskusverlagerung. Klinische Zeichen degenerativer Gelenkerkrankungen sind gewöhnlich anfangs mehrdeutig. In der Regel sind sie unterschiedlich lange nicht sehr auffällig. In fortgeschritteneren Fällen sind die klinischen Merkmale Schmerz, Bewegungsbehinderung und Muskelatrophie. Die zugrundeliegenden Veränderungen sind Knorpelzerstörung, subchondrale Sklerose, Osteophyten und eine Verdickung der Synovia. In sehr fortgeschrittenen Fällen beim Menschen tritt selbst Knochenabnutzung auf, die klinisch zu Instabilität und Subluxation führt. Bei Coxarthrosis des Menschen wird häufig Zystenbildung beobachtet. Ätiologie und Pathogenese sind dunkel oder nur teilweise aufgeklärt, und bei Tieren ist die Diagnose viel schwieriger. Oft besteht eine schlechte Korrelation zwischen der Schwere der radiographischen Verändemngen und den klinischen Zeichen.     

Bovine laminitis: clinical aspects, pathology and pathogenesis with reference to acute equine laminitis

This review deals with the features of clinical and subclinical laminitis in cattle. Prominent clinical signs of acute laminitis are a tender gait and arched back. The sole horn reveals red and yellowish discolourations within five days. In subacute and chronic cases clinical signs are less severe. In chronic laminitis the shape of the claws is altered. Laminitis is frequently followed by sole ulceration and white zone lesions. Blood tests showed no significant changes for laminitic animals. Arteriographic studies of claws affected by laminitis indicated that blood vessels had narrowed lumens. Gross pathology revealed congestion of the corium and rotation of the distal phalanx. Histopathologic studies indicate that laminitis is associated with changes of the vasculature. Peripartum management and nutrition are important factors in its aetiology. It is hypothesised that laminitis is evoked by disturbed digital circulation. In the pathogenesis of acute laminitis three factors are considered important: the occurrence of thrombosis, haemodynamic aspects of the corium, and endotoxins which trigger these pathologic events.     

Development of porcine digestive enzymes with special reference to ribonuclease

The activity of digestive enzymes was determined in the gastrointestinal tract of newborn, 1-, 3- and 5-week-old piglets and in adult pigs. The pancreas of newborn piglets contained considerable ribonuclease (RNase) activity, which continued to increase with age. After the initial values an opposite tendency was found in the intestinal contents, probably due to the increase of proteolytic degradation with advancing age. Serum RNase showed little age dependence. The time-course of development of pancreatic RNase resembled more that of proteolytic enzymes than tha of amylase. The data indicate that a high pancreatic secretion of RNase commences much before the appearance of RNA in the diet.