The fine structure of the nucleus of the hypoglossal nerve of sheep and goats]

In the small domesticated ruminants the nucleus of the hypoglossal nerve is situated in close relationship to the median line in the middle of the elongated medulla. The nucleus is divided by the obex into a rostral and a caudal portion. In the sheep, four distinct subnuclei can be recognized, whereas in the dwarf goat great variations in the arrangement of cell groups exists. In both animals large and medium sized neurons are observed. The large neurons are characterized by densely packed small organelles. The medium sized neurons vary between a pale and an electron dense type. According to the size and morphology of the vesicles three types of synaptic contacts can be differentiated. Synapses of type 2 contain clear round and flattened vesicles and are partially accompanied by subsurface cisterns.     

The regulation of feed intake and selection with special reference to poultry]

Feed intake is regulated in a dialogue between the animal and the feed, which is influenced by numerous factors. The hypothalamus has a central integrative function. Furthermore, caudal brain areas (medulla oblongata, pons) are of importance because these areas are relays of peripheral signals and gustatory afferents. All peripheral informations are integrated by various neurotransmitters and neurohormones. The function of this neuronal system is not exactly known yet. Sensorial informations, mechano-, chemo- and osmoreceptors of the gastrointestinal tract and gastrointestinal hormones are discussed as influences of the periphery. The physiological satiety function of cholecystokinin is questionable in poultry. Hepatic chemoreceptors, which are activated by various metabolites, influence the amount of feed ingested. The feed choice appears to be regulated by the same mechanisms. Our knowledge about the translation of peripheral signals into choice behaviour by changes of neurotransmitter systems is limited.     

Q fever antibody titer--follow-up study in cattle with special reference to pregnancy]

In 290 Q fever positive cattle from three 2000 head dairy farms in the former district of Erfurt (Thüringen) the course of titers was examined serologically over several months by means of the complement fixation test (CFT). In 47.2% of the cows serologically observed for 2 up to 28 months complement fixing antibodies against Coxiella burnetii could be demonstrated til the end of the investigation period. Repeated tests during pregnancy showed increase of antibody titers in the first 4 months and after a short decrease again from the 5. til the 7. month. By observing the antibody titers during several pregnancies each time a new increase comparable to a booster immunisation could be found. This may explain the persistence of Q fever antibodies in cows for several years. The results of this investigation suggest that from a high antibody titer it can not be concluded an abortion in a positive cow being caused by a Coxiella burnetii infection.     

Immunology of helminth infections, with special reference to immunopathology.

Immune responses resulting in immunity to infection or disease, share the same basic humoral and cellular mechanisms. While immunity to helminth infection has evolved to mediate rapid elimination of the parasite, the strategies evolved by the parasites themselves aim to delay this rejection process and ensure the survival and distribution of their progeny. Ineffective or incomplete immunity results in persistence of parasites or their products within the host tissues, inappropriate or chronic stimulation by parasite antigens, hyper-reactivity and tissue damage or immunopathology. A long standing classification by Gell and Coombs identifies four major types of hypersensitivity responses accounting for most of the immunopathogenesis, three of which are mediated by antibody and one, delayed type hypersensitivity (DTH), by T cells. This paper aims to give a short review of these four classical hypersensitivity reactions with particular reference to infections of large animals with helminth parasites. In addition, in view of the functionally different helper T cell subsets now identified, the existing DTH response is redefined as DTH Type 1 (Th-1 mediated) and two new classes of T cell-dependent DTH responses are proposed; DTH Type II, associated with the Th-2 type cytokines IL-4 and IL-5 and eosinophilic granuloma formation, and DTH Type III, associated with IL-4 and TGF-beta and fibrosis. Finally, some implications of immunopathology on parasite control strategies are discussed.     

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.     

The significance of CELO virus as a hatching egg contaminant with special reference to its oncogenic properties]

A group of young hamsters was injected subcutaneously in the neck region with allantoic fluid containing CELO virus. A second group received transplants of cells from tumours induced by CELO virus. Tumours developed in both groups. The latent period was shorter after transplantation than after virus inoculation. The tumours grew progressively, histologically resembling fibrosarcoma. It is recommended that hatching eggs infected with CELO virus should not be used in vaccine production.     

The vascularization of the epididymis of the boar with special reference to perfusion fixation

Vasculature of the epididymis was investigated by means of corrosion casts. In the boar, epididymal arteries form a complex network around their stem vessel, the testicular artery. Proper perfusion fixation or complete casting therefore require direct injection into one of these branches. To reach the distal cauda, cannulation of the deferential artery is further needed. Connections between all of these feeding vessels occur at the level of the vascular cone. A prominent anastomosis between an epididymal branch and the testicular artery is regularly observed under the caput epididymis. Epididymal veins drain to a large extent into the pampiniform plexus. Unlike the situation in other species, vascularization of testis and epididymis are closely associated in the boar.