Ultrastructural response of pulmonary intravascular macrophages to exogenous oestrogen in the bovine lung: translocation of the surface-coat and enhanced cell membrane plasticity and angiogenesis.

The pulmonary intravascular macrophages (PIMs) of domestic ungulates are recognised by their specific surface coat, consisting of linearly arranged globules along the external leaf of the plasma membrane. The coat is sensitive to in vitro digestion with lipolytic lipase (LPL), intravenous heparin and clinical exposure to halothane anaesthesia. The sensitivity to these experimental manipulations suggests that the globules of the coat are predominantly composed of lipoproteins (LDL). The present administration of oestradiol proprionate in castrated male calves potentiated the translocation of the surface coat into the endocytotic pathway of the PIMs. Concurrently with mobilisation of the coat, the plasma membrane was thrown into prominent arrays of lamellipodial extensions. The sprawling macrophages made extensive adhesive contacts with the lining endothelium of the capillaries. Consequently, the endothelial cells were highly attenuated and precariously maintained the integrity of the vascular wall. At some focal points, the vascular wall was penetrated by the filopodial processes of PIMs, which protruded into the perivascular space. Furthermore, there were signs of neovascularisation in the form of overt mitotic changes, sprouting and precursor capillary formation. It is conceivable that the evolving profile of angiogenesis is due to the vascular endothelial growth factor (VEGF) paracrine function of PIMs. Endothelial cell specificity has been considered an important advantage of VEGF for neovascularisation. It allows pleotrophic response of endothelial cells to proliferate and to assemble into endothelial tubes.

Estrogen-induced microvilli and microvillar channels and entrapment of surfactant-lipids by alveolar type I cells of bovine lung.

The ATI cells are simple, flat squamous epithelial cells, which are evolved to function as a component of the alveolar-capillary membrane, ideally designed for gaseous exchange. They inherently lack an active metabolic machinery and lead a precarious existence in the face of hostile environment. On the other hand, the ATI cells of the lung of ruminating animals are endowed with structure-functional properties which enable them to exert a selective barrier function against a wide range of osmotic pressure gradients at their luminal surface. Such gradients are created by a complex gaseous homeostasis due to expectoration of several gases and volatile fatty acids originating from the complex stomach of the ruminants. The purpose of this study is to examine the effect of estradiol propionate on the ultrastructure of the ATI cells and their interaction with the surfactant lipids. The lungs of estrogen and dexamethasone treated male calves were harvested for electromicroscopic examination. The evidence is presented that estradiol induced the formation of microvilli and microvillar channels at the luminal surface. At these regional modifications, intense interactions with the surfactant lipids and their entrapment into the pathways of endocytosis, took place in the squamous part of the ATI cells. Concurrently, large basal protrusions ended up as long lamellipods deep into the alveolar interstitium. The filamentous cytoskeletal network and microtubules intermixed with the translocated organelles such as Golgi apparatus and associated coated and uncoated vesicles. The results of this study support the hypothesis that estrogen regulate the selective barrier-function of the ATI cells. The entrapment of surfactant lipids under the influence of estrogen by ATI cells is a significant change perhaps in response to extracellular stimuli and expression of transmembrane receptors. It implies that these epithelial cells are specially evolved to adapt to a complex gaseous homeostasis in the lung of the ruminating ungulates.

Histopathologic alterations induced in the lungs of sheep by use of alpha2-adrenergic receptor agonists.

OBJECTIVE: To study effects of central- and peripheral-acting alpha2-adrenergic receptor agonists on lung parenchyma, platelets, and pulmonary intravascular macrophages (PIM) of sheep. ANIMALS: 12 healthy mature female sheep. PROCEDURE: Group-1 (control, n = 2) sheep received 5 ml of physiologic saline solution IV and were euthanatized 3 minutes later. Sheep of group 2 (n = 8) received xylazine (150 microg/kg of body weight, IV), then 2 sheep each were euthanatized 3, 10, or 60 minutes, or 12 hours later. Sheep (n = 2) of group 3 were given ST-91 (30 microg/kg, IV), then were euthanatized 3 minutes later. Immediately after euthanasia, the lungs were fixed intratracheally and tissue was obtained for light and electron microscopy after 1 hour. RESULTS: Pulmonary parenchymal damage or morphologic alterations in PIM and platelets were not evident in control sheep. Three minutes after xylazine administration, morphologic changes in PIM were appreciable. After 10 minutes, extensive damage to the capillary endothelium and alveolar type-I cells, intra-alveolar hemorrhage, and interstitial and alveolar edema were evident. Most PIM had complete internalization of the surface coat. Similar changes were seen 60 minutes after xylazine administration; however, by 12 hours, morphologic features of PIM and lung parenchyma were almost completely restored. Evidence of PIM activation, obvious damage to capillary endothelium, and extensive pulmonary edema also were evident 3 minutes after ST-91 administration. CONCLUSIONS: XYLAZINE induces severe pulmonary parenchymal damage when administered at clinical sedative doses in sheep; morphologic changes in PIM within 3 minutes after administration of these drugs are substantial; and platelet aggregation is not apparent.

Transmission electron microscopy of the epithelium of distal airways and pulmonary parenchyma of the goat lung.

Lungs from eight goats of mixed sexes and breeds (Cashmere, Nubian and Toggenburg) aged between 10 and 48 months were used in this study. Tissues from lung parenchyma were minced and routinely prepared for transmission electron microscopy (TEM) after using different methods of fixation. Thick sections were examined with a light microscope and samples, to include terminal bronchioles, respiratory bronchioles, alveolar ducts and alveolar membrane, were selected for ultrathin sectioning. Six cell types, ciliated, non-ciliated bronchiolar epithelial, mucus-producing, alveolar Type I, alveolar Type II and capillary endothelial cell were identified and characterised cytologically. It was established that the cell population in the distal airways is similar to that observed in other domestic mammals. The mucus-producing cell, which appears to be a common cell type in the distal airways of man and Rhesus monkey, was encountered particularly in adult goats in the present study. This study has also established that the Clara cell of the goat shows some cytological differences from those of some other mammalian species by having a large amount of SER, particularly in the apical region. Lipid vacuoles were seen to be a feature of the alveolar Type II cells; these do not appear to have been reported in other mammalian species. The study has provided a basic understanding of the morphological features of the cell population of the epithelium lining the distal airways in the goat's respiratory tract. The difference in junctional complexes between the various alveolar epithelial cells perhaps signify a different pattern of intercellular transport, thus influencing the pathogenesis and resolution of alveolar pulmonary edema.

Ultrastructural and immunocytochemical study of the pulmonary intravascular macrophages of Escherichia coli lipopolysaccharide-treated sheep.

BACKGROUND: Pulmonary intravascular macrophages (PIMs) of sheep, cattle, goats, and horses have a novel heparin-sensitive chain of globules, called a surface coat, on their plasma membrane. The globules are arranged at a distance of 32-39 nm from the plasma membrane of PIMs. Intravascular nonbiological tracer particles complex with these globules prior to their endocytosis by the PIMs. METHODS: We conducted a preliminary in vivo time-course study in sheep to investigate responses of the coat globules to a single dose of Escherichia coli lipopolysaccharide (E. coli LPS). Six sheep (6-9 months of age) were used in this study, and five of them were intravenously injected with E. coli (1 microgram/kg body weight) and euthanised at 3, 8, 10, 30, and 180 min (n = 1 each) after treatment. One sheep injected with saline solution served as the control. Acid phosphatase (AcPase) cytochemistry and immunocytochemistry using a polyclonal antibody were employed to localize secretory activity and E. coli LPS respectively in the PIMs. RESULTS: The surface coat of PIMs disappeared rapidly following the LPS administration. Escherichia coli LPS micelles and coat globules were colocalized as a complex in the endosomes of PIMs. At 8-10 min following the treatment, endosomal and the other membranes were disrupted, and the LPS was identified in cytoplasm and nuclear matrix of PIMs simultaneously with the development of pulmonary interstitial edema. Progression of AcPase reactivity along the nucleus-Golgi complex axis coupled with intense buildup of coated transport vesicles within 30 min of the LPS injection suggested enhanced biosynthetic activity in the PIMs. CONCLUSIONS: This study provides initial data on the sensitivity of the coat globules and their possible role in the endocytosis of E. coli LPS by the PIMs. Rapid biosynthetic activation of PIMs concurrent with loss of the coat and treatment with the LPS probably results in the secretion of inflammatory substances and contributes to the enhanced susceptibility of sheep to endotoxin-induced lung pathology.

Surface coat of sheep pulmonary intravascular macrophages: reconstitution, and implication of a glycosyl-phosphatidylinositol anchor.

BACKGROUND: Pulmonary intravascular macrophages (PIMs) of sheep have a globular surface coat that facilitates endocytosis of tracer particles and Escherichia coli lipopolysaccharide, and is disrupted by the heparin and Brefeldin A treatments. The present study investigated the in vivo dynamics of the coat globules following heparin-mediated removal, and the mechanism of globule organization on the plasma membrane of PIMs in vitro. METHODS: Sheep were administered heparin at a dose of 50 IU/kg body weight IV, and euthanised at 30 min, 3, 6, 12, 48, and 120 hr (n = 2 for each treatment) after the treatment. Control sheep (n = 2) were injected with normal saline solution. The tissues were processed for an ultrastructural examination and acid phosphatase (ACPase) cytochemistry. Heparin-treated lungs were subjected to morphometric analysis of the coat globules. Lung tissues from normal sheep (n = 2) were incubated with phosphatidylinositol-specific-phospholipase C (PIPLC; 2 IU/ml PBS) in vitro for 30 and 75 min. RESULTS: Heparin study: The ultrastructural and morphometric data showed that the coat globules were removed at 30 min and reconstituted within 48 hr of the treatment. The PIMs showed prominent Golgi complexes associated with secretory vesicles, microtubules, and centriole between 3-12 hr of heparin treatment. Acid phosphatase cytochemistry also demonstrated secretory activity in the Golgi complexes of PIMs during the coat reconstitution. PIPLC study: The coat globules of PIMs were removed in a time-dependent mode by the PIPLC treatment without damage to other cell organelles. CONCLUSIONS: This study demonstrates a time-dependent reconstitution of the coat of PIMs in conjunction with secretory activity following heparin-mediated removal, probably through sequestration of the globules from blood. This ability is of functional significance as the coat mediates particle endocytosis by the PIMs. The results also suggest the presence of a glycosyl-phosphatidylinositol (GPI) anchor in tethering of globules on the plasma membrane of PIMs to offer a structural basis for their integrity in pulmonary vascular flow.

Surface coat of sheep pulmonary intravascular macrophages is reconstituted following brefeldin A-mediated endocytosis.

Pulmonary intravascular macrophages (PIMs) of sheep have a globular coat on their surface which is mobilized by heparin and halothane, and is implicated in the endocytosis of tracer particles and Escherichia coli lipopolysaccharide. Brefeldin A (BFA) was used in vivo to investigate the effects of a pre-Golgi secretion blocker on the integrity of surface coat, and to know whether PIMs produce coat globules. Sheep were injected intravenously with BFA to reach a one time concentration of 2-5 microgram/ml of plasma, and euthanised at 10, 30, 45, 120 and 180 min (n = 1) post-treatment. Lungs were fixed in situ with 2% glutaraldehyde and 2.5% paraformaldehyde for 30 min. Lung tissues were processed for routine ultrastructural examination including treatment with tannic acid (0.1%), and for the acid phosphatase (ACPase) cytochemistry to identify Golgi complex and enzyme-rich endocytic vesicles. Surface coat was endocytosed by the PIMs within 10 min of BFA treatment through long ACPase-negative endocytic channels and degraded in the acid hydrolase-rich lysosomes. Golgi complex membranes were tubulated and were associated with prominent microtubules, centrioles and secretory vesicles. However, trans-Golgi network was not affected by BFA administration. The coat of PIMs was reconstituted within three hours of BFA-induced endocytosis, in concurrence with signs of enhanced biosynthetic activity. It seems that PIMs do not synthesize the globules, and rather sequester from the plasma to organize a surface coat. It is possible that PIMs contribute a membrane anchor or a receptor to facilitate reconstitution of the coat to perform multiple rounds of globule-mediated cell functions.

Evidence that halothane anaesthesia induces intracellular translocation of surface coat and Golgi response in equine pulmonary intravascular macrophages.

The pulmonary intravascular macrophages (PIMs) of horse contain a unique electron-dense globular surface-coat which is arranged in a linear fashion in conformity with the contours of the cell membrane. The coat is sensitive to heparin treatment and to the digestive effect of lipolytic lipase, suggesting that the coat is predominantly composed of lipoproteins. During the present study, ultrastructural features of PIMs were analysed after exposing horses to halothane inhalation which was chosen as the model agent of lipid-soluble anaesthetic. The surface-coat showed acute sensitivity to halothane by disappearing almost completely from the surface after 1-2 h of exposure. The cell membranes were thrown into extraordinary arrays of lamellipods, pseudopods and veils. Concurrently, the globular units of the coat were translocated into the endosomal-lysosomal system, most probably via receptor-mediated endocytosis. There was a high profile of the expanded Golgi apparatus especially the trans Golgi network (TGN) in close association with the centrioles and microtubules. Cytochemistry revealed an enrichment of the Golgi complex with acid phosphatase activity. On the other hand, halothane showed an inhibitory effect on the lysosomal acid phosphatase of the PIMs. It is proposed that the Golgi response occurred as an obligatory concomitant of internalization of the surface-coat and its subsequent passage through endosomal-lysosomal system. The acid phosphatase activity as a marker enzyme of the expanded Golgi is correlated with metabolic effects of the internalized coat which is unique to the pulmonary intravascular macrophages. Furthermore, the intense expression of acid phosphatase at the Golgi level of the PIMs may signify a component of secretory phenotype in order to produce vasoactive mediators at the onset of stressful stimuli triggered by the halothane anesthesia.

Ultracytochemical study of multiple dose effect of monastral blue uptake by equine pulmonary intravascular macrophages (PIMs).

The pulmonary intravascular macrophages (PIMs) of the ponies possess all the characteristics of a fully differentiated resident macrophage, which forms adhesive plaques with the capillary-endothelial cells. In addition, it has a unique surface coat which does not conform to the concept of a carbohydrate rich membrane bound glycocalyx generally associated with macrophages. We studied the responses of these cells especially in the context of its globular surface coat to multiple doses of MB intravenously: 0.2 ml/kg body copper tracer substance. The ponies were treated with three doses of MB intravenously: 0.2 ml/kg body weight on day 0, 0.1 ml/kg at 48 h and a 0.05 ml/kg at 96 h after the first dose. The examination of lung tissue at the ultrastructural level revealed internalization of MB following complexing with the surface coat globules along the entire cell surface. The cell surface was extensively ruffled in the form of several lamellipods. The MB-globule complex was internalized mostly at the coated pits whereas concurrent internalization of nascent globules of the coat took place at the ruffled surface. In the former, the internalized material was seen in small, medium and large phagolysosomes which stained intensely for acid phosphatase, whereas in latter case enzyme activity was entirely absent in all the nascent globules carrying endosomes. Simultaneously there was hypertrophy of the Golgi complex, which showed intense staining for acid phosphatase. Relative to the Golgi response, acid phosphatase-positive tubular lysosomes in close association with extensive bundles of microtubules were conspicuous, thus adding to the battery of cell organelles of secretory pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Presence of pulmonary intravascular macrophages in the equine lung: some structuro-functional properties.

The pulmonary intravascular macrophages (PIMs) have been described in several species of animals. This study demonstrates for the first time that the equine lung has PIMs as resident phagocytes in its microvasculature. Their salient features such as globular surface coat, structures of the endocytic pathway, and related cell organelles closely resemble those of the calf, goat, and sheep. The exquisite organization of the coat globules in the form of a linear chain was structurally similar to the lipolytic lipase and the heparin-sensitive globular coat from PIMs of calf, goat, and sheep. Monastral blue (MB) when employed as a tracer to assess the phagocytic properties of equine PIMs induced similar modification of the globules of the coat into lipid droplets, reminiscent of neutral lipids. Lipids droplets (modified coat globules) were delivered into acid phosphatase-positive endosomes and lysosomes. Concurrently, the unaltered globules of the coat, probably internalized via fluid-phase constitutive pinocytoses, followed a different endocytic pathway. Large-scale platelet uptake by the PIMs was observed with thrombocytopenia in MB-treated ponies. The possible significance of hypothetical LDL-coat and the endocytic organelles as equivalents of synthetic apparatus of vasoactive lipids in the PIMs of horse needs to be assessed in future studies.

In vivo interaction of cationised ferritin with the surface coat and endocytosis by pulmonary intravascular macrophages: a tracer kinetic study.

The pulmonary intravascular macrophages (PIMs) of goat lung contain a unique electron-dense coat consisting of globular units arranged in a linear fashion along the cell surface. The globules showed a high affinity for cationised ferritin (CF) within 2-5 min of its intravenous injection, whereas native ferritin did not bind with the globules of the coat. The CF-labelled (hybrid) globules were subsequently internalised via receptor-mediated endocytosis. During 2-5 min of CF treatment, hybrid globules rapidly reached endosomes, multivesicular bodies and lysosomes, which acquired a high visibility in the form of interconnected tubular structures in the area of the Golgi complex. It is suggested that globular units of the surface coat, by showing high affinity for CF, resemble negatively charged large low density lipoprotein molecules. It supports our earlier postulate that heparin and lipolytic lipase sensitive globules of the surface coat of PIMs may be composed of lipoprotein-like substances. The ubiquity of the surface coat as a differentiated surface structure perhaps enables PIMs to cope with a barrage of stimulatory and suppressive signals within the microcirculatory units of the lungs of these animals.

In vivo monastral blue-induced lamellar-bodies in lysosomes of pulmonary intravascular macrophages (PIMs) of bovine lung: implications of the surface coat.

We previously reported that the pulmonary intravascular macrophages (PIMs) of sheep, goat, and calf lung contained a heparin and a lipolytic lipase sensitive surface coat by using tannic acid as a component of paraformaldehyde-glutaraldehyde-based fixative. The implication of this sensitivity was that the surface coat was predominantly comprised of lipoprotein-like substance. In this study we report that monastral blue (MB) used as a vascular tracer interacted with the coat globules and lost its original particulate appearance. Its precise localization in the PIMs was in combination with altered macromolecules of the surface coat in the form of lipid droplets, which conformed to the conventional view of neutral lipids. In contrast, pigment particles examined in their native state resembled metallic particles as electron-dense elliptical rods. The lipid droplets were subsequently internalized through endocytic route and found their access into the lysosomal compartments of PIMs at the electron microscopic level. Lamellar bodies (LLBs) arose from the lysosomal matrix after the entry of lipid droplets in the secondary lysosomes. Acid phosphatase activity was located in secondary lysosomes as well as in endosomes. These observations suggest that coat granules of the PIMs acted as a carrier of exogenous MB particles to deliver the complex to the lysosomal compartment where partial digestion lead to the formation of lamellar bodies. The implications of MB (cationic dye) as a vascular tracer for studying phagocytic index of PIMs in the light of their coat and the rapid development of LLBs are discussed. It is proposed that MB by initially combining with the surface coat provokes mobilization of intracellular lipid pools. In this way metabolism of vasoactive lipid in the PIMs is stimulated to influence the dynamics of pulmonary circulation in the calves.

An uptake of cationized ferritin by alveolar type I cells in airway-instilled goat lung: distribution of anionic sites on the epithelial surface.

The present study has investigated ultrastructural localization of anionic sites on the luminal surface of the alveolar epithelium of goat lung by direct airway instillation of cationized ferritin (CF) in the cranial lobe of the right lung through a bronchoscope. The cationic probe decorated preferentially the luminal plasmalemmal vesicles and plasmalemma proper of alveolar type I cell. This indicated the presence of highly charged anionic microdomains at these binding sites. The ligand was internalized in the free plasmalemmal vesicles of alveolar type I cell within 2 min. Heavy decoration of vesicles at 5 min of perfusion indicated that the amount of CF internalization increased with its concentration in the alveoli. It is suggested that exposure of alveolar surface to several gases of ruminal-origin induces changes in the surface charge of luminal plasmalemma of alveolar type I cells. The significance of these anionic plasmalemmal sites is discussed in relation to the adjustment of osmotic pressure gradient across the alveolar-capillary membrane of the ruminant lung.

Morphology of pulmonary intravascular macrophages (PIMs) in ruminants: ultrastructural and cytochemical behavior of dense surface coat.

Recent studies have indicated that pulmonary intravascular macrophages (PIMs) are a resident cell population which in structure and function resemble mature macrophages of the mononuclear phagocyte system (MPS) in various domestic species, particularly the ruminants. The ultrastructural features of PIMs of the goat and calf lungs were studied by using vascular perfusion and direct airway instillation of fixatives. Staining with tannic acid as a component of paraformaldehyde-glutaraldehyde-based fixative revealed the presence of an electron-dense coat on the surface of the cell membrane of the PIMs. The surface coat disappeared after heparin infusion and after enzymatic digestion with lipolytic lipase, suggesting that the surface coat was predominantly lipoprotein in nature. The lipoprotein coat was organized in the form of a linear chain of spherical globules with a consistent periodicity created by the intervening translucent space between individual globules. The surface coat was separated from the outer-leaflet of the cell membrane by an empty space measuring 35-39 nm in width. PIMs possessed a significant number of coated pits and coated vesicles, the cell organelles of receptor-mediated endocytosis of lipoproteins. In concurrence with the coated pits and vesicles, microtubules, multivesicular bodies, and lipoprotein-positive vesicles were also observed. It is conceivable that PIMs are involved in lipid metabolism and are the major source of vasoactive substances, which significantly influence both the dynamics of pulmonary circulation and the surfactant turnover of the ruminant lung.

Histologic and ultrastructural alterations in lungs of rats exposed to sub-lethal concentrations of hydrogen sulfide.

Fischer-344 rats were killed 1, 18, and 42 hr after a single 4-hr exposure to an atmosphere of 0, 116, or 615 mg m-3 of hydrogen sulfide (H2S). Lungs, fixed by the intratracheal route, were examined by light and electron microscopy. Histologic changes were transient and mainly present in rats exposed to 615 mg m-3 H2S. Lesions included severe but transitory pulmonary edema and fibrinocellular alveolitis which was restricted to the proximal alveolar region of the lung. Electron microscopically, ciliated bronchiolar cells were the only cells that developed necrosis; they were rapidly replaced by mitosis. Alveolar endothelium had cytoplasmic blebs, but alveolar epithelium had minor changes. No mast cell degranulation was detected in lungs with edema. A 4-hr exposure to 615 mg m-3 is markedly edematogenic for the lung but only moderately cytotoxic for pulmonary cells.

Cytotoxic effects of 3-methylindole on alveolar epithelial cells and macrophages: with special reference to microtubular and filamentous assemblies in alveolar type I cells of bovine lung.

The alveolar type I cell is a major permeability barrier between the pulmonary interstitium and alveolar spaces and its thin cytoplasmic processes are greatly susceptible to injury. These cells are often observed to undergo progressive vesiculation, vacuolization and desquamation during 3-methylindole (3MI)-induced acute pulmonary edema after oral administration in goats and cattle. The present study describes proliferation of SER and the presence of polymerized tubulin in the form of microtubules arranged in large bundles shown at ultrastructural level as well as with immunofluorescence staining for tubulin in alveolar type I cells 72 hours after 3MI treatment. Such changes were not seen in pulmonary endothelial cells, alveolar type II cells, alveolar macrophages and neutrophils. The possible role of microtubules in alveolar type I cells as a mechanistic support to resist disruption against the forces of interstitial and alveolar edema is compared with alveolar type II cells, alveolar macrophages and neutrophils. The latter cells undergo dynamic movements in response to inflammatory stimuli and therefore did not show microtubules in their cytoplasm.

Ultrastructural study of the alveolar-capillary membrane and the tubular endoplasmic reticulum in alveolar type I cells of the caprine lung.

The ultrastructural features of alveolar type I cells of the goat lung were studied by using vascular perfusion and direct airway instillation of fixatives. The morphological features of smooth endoplasmic reticulum (SER) were characterized by measuring the diameter of individual SER tubules which conformed in size and appearance to the tubular endoplasmic reticulum (TER) already described in various types of epithelium. The TER appeared as large tubular aggregates in a palisade arrangement; these aggregates ramified into various areas of the extended cytoplasm of alveolar type I cells. The TER also existed as a mixture of short cisternae and vesicles, and glycogen alpha particles were present in the non-perikaryonic portion of the cell. The different forms of TER had varying relationships to the plasmalemma. The interchangable configurations seen in the structure of TER indicated the functional modalities of the cells and were comparable to similar structural modifications in electrolyte-secreting cells. The role of TER, microtubules, and large populations of endocytic vesicles in the alveolar type I cells in the goat lung is examined in the context of physiological eructation of rumenal gases and the absorption of electrolyte-rich fluids which escape into the lung at each eructation in ruminants.

Impairment of sympathetic pulmonary vasoconstriction by 3-methylindole in cattle.

Sixteen Holstein cattle allotted into 4 groups (4 cattle/group) were each given a single oral dosage of 0.2 g of 3-methylindole (3MI)/kg of body weight. The groups were killed at 12, 24, 48, and 72 hours, respectively, after 3MI administration. Comparison of clinical signs, pathologic pulmonary lesions, and in vitro pulmonary artery responses to pharmacologic stimuli was made between the 4 treated groups and 8 control Holstein cattle of similar age. Clinical signs of pulmonary distress first appeared 8 to 12 hours after 3MI administration. After 20 hours, clinical signs included dyspnea, moderate depression, and a marked expiratory grunt. A partial remission of these clinical signs was seen between 30 and 45 hours after 3MI administration. After remission, the cattle had clinical signs of severe dyspnea and depression and expiratory grunts were more pronounced. Pathologic pulmonary lesions, including heavy rubbery lungs, dilated interlobular septae, and subplural air bullae characteristic of pulmonary edema and interstitial emphysema were observed. The lungs of treated cattle did not collapse when the thorax was incised at necropsy. In vitro pulmonary artery strips contracted dose dependently to norepinephrine (NE). Group I tissues (12 hours after 3MI administration) responded similarly to control samples. Group II tissues (24 hours after 3MI administration) had a significant inhibition (P less than 0.05) in response to NE stimulation as compared with controls.

Erythrophagocytosis in alveolar capillaries of goat lung: ultrastructural properties of blood monocytes.

Glutaraldehyde-perfused lungs of 5 adult male and female goats were prepared for electron microscopy to study the properties of blood monocytes in the alveolar capillaries, with particular reference to intravascular erythrophagocytosis. Ultrastructural evidence is presented that the majority of intravascular monocytes were active in forming large uropods and filipods and were vigorously phagocytic for erythrocytes. Erythrocytes were engulfed intact and subsequently fragmented. The fragments were hemolyzed and eventually converted into ghost erythrocytes and siderosomes. An electron-dense protein coat was consistently seen on the outer surface of the cell membrane of monocytes. Coated pits, endocytosis and some indication of internalization of the surface coat were evident. It is suggested that blood monocytes in the lung undergo a process of maturation to differentiate into active phagocytes as immediate precursors of alveolar macrophages.

Atypical cilia in ciliated cysts of the parathyroid glands of dogs exposed to ozone.

This report deals with the occurrence of atypical cilia in ciliated cysts of parathyroid glands in dogs after exposure to ozone inhalation at 0.75 ppm close level for 48 h. Electron microscopic examination revealed cytoplasmic blebs with none, one, two ore more axial microtubule complexes (compound) surrounded by a single membrane and containing little or excessive matrix. Also seen where helicoidal cilia. The present anomalous behaviour of the cilia in the prevalent ciliated cysts in ozone treated dogs is consistent with the previously described effects of ozone inhalation on the parathyroid glands.