B.W. Manktelow

Generalized glycogen storage disease in sheep

Abstract Four cases of generalized glycogen storage disease are reported in a flock of Corriedale sheep. The storage occurred extensively in neurones, particularly of the brain stem and cord and in cardiac, striated and smooth musculature. The appearance and distribution of the lesions closely resemble glycogenosis Type II or Pompes disease of man.

Bordetella parapertussis from lambs.

Abstract Extract Madam:—An organism identified as Bordetella parapertussis has been isolated in significant numbers from nasal swabs, bronchial washings and the lungs of 6–10 month old lambs showing signs of pneumonia. It has also been isolated from normal lambs but attempts to recover it from adult sheep have so far been unsuccessful (Table I).

Hairy shaker disease of lambs

Abstract Extract Records from New Zealand diagnostic stations reveal that, at least since 1957, a syndrome in lambs has been encountered which is characterized at birth by excessively hairy fleeces and fine muscular tremors of head and limbs which are often severe enough to cause inco-ordination. These features have given rise to the apt colloquial name of hairy shaker disease. The condition was first reported by Hartley and Kater (1962). Histological examination of the central nervous system usually reveals hypomyelinogenesis which is most marked in the spinal cord and affects all columns of white matter. Some lambs may have a hairy fleece but do not show nervous signs or histological evidence of hypomyelinogenesis. Hairy lambs with and without chorea appear to have a low survival rate and may die within two or three months. Others survive but have a slow rate of growth. If nervous signs are present they tend to regress over a period of several months. The condition has been seen in Romney × Romney, Sout...

Respiratory tract-associated lymphoid tissue in conventionally raised sheep

The distribution and morphological features of respiratory tract-associated lymphoid tissue was investigated in 20 clinically healthy sheep aged from 6 months to 9 years. Five different forms of lymphoid tissue were identified, but their distribution varied between regions of the respiratory tract and between individuals. Scattered lymphoid cells were the most predominant form. Dense lymphoid aggregations were frequently seen in the pharyngeal tonsil and bronchioles. They were less common in the mid-nasopharynx and about the opening of the auditory tube, occasionally seen in the anterior nasopharynx, trachea and bronchus and rarely found in the regions of the nasal conchae, nostril, nasal vestibule and epiglottis. Nodular lymphoid aggregations with morphologically distinct lympho-epithelium were seen only in the pharyngeal tonsil and opening of the auditory tube region. Small numbers of intra-epithelial lymphoid cells were always present throughout the mucosa, but intraluminal lymphocytes were observed mainly in the regions of pharyngeal tonsil, trachea, bronchi and large bronchioles. The respiratory tract-associated lymphoid tissue is less developed in sheep than in most other species studied, except perhaps cattle.

Mast cells in the bovine lower respiratory tract: Morphology, density and distribution

The lower respiratory tract of six 8-day-old calves and six adult cows was fixed in either isotonic formal-acetic-acid or neutral buffered formalin in order to study the morphology, density and distribution of mast cells. They were found at all levels of the tract with the highest density in the major bronchi. Tissues from cows had significantly more mast cells than those from calves. There were significantly more mast cells detected in calf airways fixed with isotonic formal-acetic-acid compared with those seen in the same tissues fixed with neutral buffered formalin. Regardless of the age and fixation, mast cells were located predominantly in the alveolar septa and in the lamina propria of airways. They were also commonly encountered within the mucosal epithelium of the trachea. Ultrastructurally, mast cells in bovine airways and lung contained two types of intracytoplasmic granules as described in other species.

Pathogenesis and red blood cell destruction in haemoglobinaemic leptospirosis

Sequential morphological changes were seen in RBCs, spleen and liver from hamsters during the development of haemoglobinaemia following infection with Leptospira interrogans serovar ballum. Spleens from pre-haemoglobinaemic hamsters showed sequestration of RBCs and erythrophagocytosis but to a lesser degree than was seen in the haemoglobinaemic hamsters. Erythrophagocytosis and RBC sequestration were also seen in the liver, particularly in the haemoglobinaemic animals. None of these changes was seen in the RBCs, spleens and livers from moribund and dead hamsters suffering from non-haemoglobinaemic disease resulting from infection with Leptospira interrogans serovar pomona. Intracellular leptospires were readily identifiable within the spleens and livers of hamster infected with both ballum and pomona. It is suggested that leptospiral toxins affect RBC metabolism and eventually RBC morphology. The affected cells are detected and removed by the reticulo-macrophage system, usually before intravascular haemolysis can take place. If the toxins affect a certain enzyme or biochemical pathway, there are sufficient normal metabolic differences in RBCs between animals of different species and, in the same species of animal, between the same and different aged animals, to explain the differing susceptibilities of the RBCs to leptospiral toxins.

The potential role of the ovine pharyngeal tonsil in respiratory tract immunity: A scanning and transmission electron microscopy study of its epithelium

The mucosal epithelium of the pharyngeal tonsil was studied in 10 conventionally raised sheep by scanning and transmission electron microscopy. The surface of the tonsil was covered by two types of topographically and ultrastructurally distinct epithelium. The epithelium overlying the lymphoid follicle region (follicle-associated epithelium) was compressed by adjacent ciliated epithelium and consisted of predominantly non-ciliated cells of varying height. The majority of these cells possessed microvilli or microfolds of varying number, height and density on their surface. Small numbers of squamous cells and, occasionally, intermediate cells were also present in these areas. Ultrastructurally, the microvillous cells showed features similar to M cells which occur in other mucosal sites. They contained cytoplasmic vesicles and vacuoles and formed intercellular digital junctions. Between these cells was a heavy infiltration of lymphoid cells. Focal disintegration of the mucosal epithelium was occasionally seen. The epithelium covering non-follicle areas consisted of mainly ciliated cells interspersed with some goblet cells and squamous cells, morphologically resembling those elsewhere in the respiratory tract. These findings have provided evidence which confirms that the ovine pharyngeal tonsil is part of the respiratory tract-associated lymphoid tissue.

Mast Cells in the Ovine Lower Respiratory Tract: Heterogeneity, Morphology and Density

The lower respiratory tract (LRT) of 6 adult sheep was fixed in either isotonic formalin-acetic acid or neutral buffered formalin in order to study the heterogeneity, morphology and density of mast cells (MCs). Two subtypes of MCs were found, one histochemically similar to connective tissue MCs (formalin resistant) and the other similar to mucosal MCs as found in the intestine of the rat (formalin sensitive). Although both subtypes were present at all levels of the tract, formalin-sensitive MCs were significantly more abundant (p less than 0.01) at all levels, and their density increased distally from the trachea to the peripheral lung. The formalin-sensitive MCs were predominantly located in the alveolar septa and in the superficial lamina propria of airways and less frequently within the airway epithelium. The MCs in the ovine LRT were found to be morphologically heterogeneous at both the light-microscopic and electron-microscopic levels. These findings indicate that ovine respiratory tract MCs have similarity to human lung MCs, and therefore potential for use as a model for the study of human allergic disease of the respiratory system.

Pneumonia in Lambs Inoculated with Bordetella parapertussis: Bronchoalveolar Lavage and Ultrastructural Studies

Eight colostrum-deprived lambs were inoculated intratracheally with ovine isolates of Bordetella parapertussis. Fluids obtained by bronchoalveolar lavage had a large increase in total cell counts 24 hours after inoculation; up to 93% of cells were neutrophils. From 3 days after inoculation, the number of alveolar macrophages in lavage samples was markedly increased. From 5 days onwards, many alveolar macrophages had moderate to severe cytoplasmic vacuolation. Topographically, tracheal and bronchial epithelium was covered by a large amount of inflammatory exudate 24 hours after inoculation. Later, the tracheobronchial epithelium showed focal extrusions from ciliated cells, which were occasionally associated with B. parapertussis organisms. Ultrastructurally, cytopathological changes associated with B. parapertussis infection were mild focal degeneration of airway epithelium with slight loss of cilia, moderate to severe degeneration of type I and type II alveolar epithelial cells, and focal inflammation in the lungs. These results suggest that the primary targets of B. parapertussis infection are alveolar macrophages and the epithelial cells of bronchioles and alveoli.

Experimental induction of pneumonia in mice with Bordetella parapertussis isolated from sheep

The intranasal inoculation of mice with a suspension of ovine isolates of Bordetella parapertussis killed about 11 per cent of animals (four out of 34) between 2 to 3 days post-inoculation and produced a subacute bronchopneumonia morphologically similar to early lesions of naturally occurring ovine chronic non-progressive pneumonia. Pulmonary lesions characterized by alveolar septal congestion and oedema, focal alveolar haemorrhage and intraalveolar and septal infiltration by neutrophils and macrophages were seen in the early stages. Bronchioles often contained an exudate of macrophages, neutrophils and fibrin and later hyperplasia of perivascular and peribronchiolar lymphoid tissue and fibrosis of the interalveolar septa were evident. Electron microscopy revealed extensive degenerative changes in the alveolar epithelium and alveolar macrophages. Pure cultures of B. parapertussis were consistently recovered from infected lungs from 12 h after inoculation to pid 6. Intact organisms and organisms showing varying degrees of degeneration were found free in alveolar spaces or phagocytosed by alveolar macrophages.