Morphology and Morphometry of the Lung in Corn Snakes (Pantherophis guttatus) Infected with Three Different Strains of Ferlavirus.

Ophidian paramyxovirus (ferlavirus) is a global threat to reptilian sauropsids in herpetological collections, with occasional but fatal effects. This study characterizes the effects of three different genetic strains of ferlavirus on the dynamic changes of histology and morphometry of the lung of corn snakes (Pantherophis guttatus). Lungs from 42 corn snakes were either sham-infected or infected experimentally under standardized conditions. From 4 to 49 days after intratracheal inoculation, the lungs were examined qualitatively and quantitatively. Progressive microscopical changes were seen in the lung. Initially, increased numbers of heterophils were observed in the interstitium followed by proliferation and vacuolation of epithelial cells lining faveoli. Electron microscopy revealed loss of type-I pneumocytes, hyperplasia of type-II pneumocytes, and interstitial infiltrates of heterophils and mononuclear cells. With progression of disease the respiratory epithelium was initially overgrown by transformed type-II pneumocytes and later became multilayered. The results of the study suggest that the respiratory capacity of the lungs declines with disease development. The dynamics of disease development and histopathology differed in snakes infected with different ferlavirus genogroups. Animals infected with virus genogroup B developed histopathological changes and morphometric changes more rapidly and of greater intensity than snakes infected with viruses from genogroups A or C.

Using heart rate to predict energy expenditure in large domestic dogs.

The aim of this study was to establish heart rate as a measure of energy expenditure in large active kennel dogs (28 ± 3 kg bw). Therefore, the heart rate (HR)-oxygen consumption (V˙O2) relationship was analysed in Foxhound-Boxer-Ingelheim-Labrador cross-breds (FBI dogs) at rest and graded levels of exercise on a treadmill up to 60-65% of maximal aerobic capacity. To test for effects of training, HR and V˙O2 were measured in female dogs, before and after a training period, and after an adjacent training pause to test for reversibility of potential effects. Least squares regression was applied to describe the relationship between HR and V˙O2. The applied training had no statistically significant effect on the HR-V˙O2 regression. A general regression line from all data collected was prepared to establish a general predictive equation for energy expenditure from HR in FBI dogs. The regression equation established in this study enables fast estimation of energy requirement for running activity. The equation is valid for large dogs weighing around 30 kg that run at ground level up to 15 km/h with a heart rate maximum of 190 bpm irrespective of the training level.

Morphological Pulmonary Diffusion Capacity for Oxygen of Burmese Pythons (Python molurus): a Comparison of Animals in Healthy Condition and with Different Pulmonary Infections.

A qualitative and quantitative morphological study of the pulmonary exchange capacity of healthy and diseased Burmese pythons (Python molurus) was carried out in order to test the hypothesis that the high morphological excess capacity for oxygen exchange in the lungs of these snakes is one of the reasons why pathological processes extend throughout the lung parenchyma and impair major parts of the lungs before clinical signs of respiratory disease become apparent. Twenty-four Burmese pythons (12 healthy and 12 diseased) were included in the study. A stereology-based approach was used to quantify the lung parenchyma using computed tomography. Light microscopy was used to quantify tissue compartments and the respiratory exchange surface, and transmission electron microscopy was used to measure the thickness of the diffusion barrier. The morphological diffusion capacity for oxygen of the lungs and the anatomical diffusion factor were calculated. The calculated anatomical diffusion capacity was compared with published values for oxygen consumption of healthy snakes, and the degree to which the exchange capacity can be obstructed before normal physiological function is impaired was estimated. Heterogeneous pulmonary infections result in graded morphological transformations of pulmonary parenchyma involving lymphocyte migration into the connective tissue and thickening of the septal connective tissue, increasing thickness of the diffusion barrier and increasing transformation of the pulmonary epithelium into a columnar pseudostratified or stratified epithelium. The transformed epithelium developed by hyperplasia of ciliated cells arising from the tip of the faveolar septa and by hyperplasia of type II pneumocytes. These results support the idea that the lungs have a remarkable overcapacity for oxygen consumption and that the development of pulmonary disease continuously reduces the capacity for oxygen consumption. However, due to the overcapacity of the lungs, this reduction does not result in clinical signs and disease can progress unrecognized for an extended period.

[Echocardiography in Boid snakes: Demonstration and blood flow measurements]. / Echokardiographische Untersuchungen bei Boiden: Darstellung und Blutflussmessungen.

OBJECTIVE: Comparative echocardiography and blood flow measurements in different boid species. MATERIALS AND METHODS: 51 healthy snakes from seven different species were examined echocardiographically under standardized conditions. The heart and the great vessels were displayed using 2-D-ultrasonography. Pulsed-wave doppler technique measurements of the blood flow within the vessels were performed and results analyzed statistically. RESULTS: The examinations could be performed in non-sedated snakes in ventral recumbency. The best image quality was obtained using the ventrolateral coupling site. An examination scheme applicable to all examined snake species was established. Diversity in the anatomy of vessels could be detected in different snake species. A characteristic shape of the curve demonstrating the blood flow against time could be shown for the respective vessels. There were positive correlations between the size of the snakes and the absolute blood flow (total flow, systemic flow, pulmonary flow to body length: p<0.001; r=0.770; r=0.627; r=0.766; respectively to body mass: p<0.001; r=0.815; r=0.698; r=0.788), as well as negative correlations between the size of the animals and the blood flow relative to body mass (total flow, systemic flow, pulmonary flow to body length: p<0.001; r=-0.533; r=-0.512; r=-0.478; respectively total flow to body mass: p<0.001; r=-0.768). CONCLUSION AND CLINICAL RELEVANCE: When using standardized conditions, echocardiography in boid snakes is a useful diagnostic tool for the assessment of cardiac function. Reference values provided in this study serve as a basis for ultrasound examination in veterinary practice.

Exposure to cold but not exercise increases carbon turnover rates in specific tissues of a passerine.

Carbon turnover differs between tissues within an animal, but the extent to which ecologically relevant increases in metabolism affect carbon turnover rates is largely unknown. We tested the energy expenditure and protein turnover hypotheses that predict increased carbon turnover, either in association with increased daily energy expenditure, or in concert with tissue-specific increased protein metabolism. We used stable-isotope-labeled diets to quantify the rate of carbon turnover in 12 different tissues for three groups of zebra finches (Taeniopygia guttata): cold-exposed birds kept at ambient temperatures below their thermoneutral zone, exercised birds that were flown for 2 h per day in a flight arena, and control birds that were kept at ambient temperatures within their thermoneutral zone and that were not exercised. We found that increases in metabolism associated with cold-exposure but not exercise produced measurable increases in carbon turnover rate of, on average, 2.4+/-0.3 days for pectoral muscle, gizzard, pancreas and heart, even though daily energy intake was similar for exercised and cold-exposed birds. This evidence does not support the energy expenditure hypothesis, and we invoke two physiological processes related to protein metabolism that can explain these treatment effects: organ mass increase and tissue-specific increase in activity. Such changes in carbon turnover rate associated with cold temperatures translate into substantial variation in the estimated time window for which resource use is estimated and this has important ecological relevance.

Structural flexibility of the intestine of Burmese python in response to feeding.

The small intestine of Burmese pythons, Python molurus bivittatus, undergoes a remarkable size increase shortly after feeding. We studied the dynamics, reversibility and repeatability of organ size changes using noninvasive imaging techniques. We employed light and electron microscopy, flow cytometry and immunohistology to study the cytological mechanisms that drive the size changes of the small intestine. Within 2 days of feeding, the size of the small intestine increased to up to three times the fasting value. The size changes were fully reversible and could be elicited repeatedly by feeding. These enormous size changes were possible because the mucosal epithelium of the small intestine is a transitional epithelium that allows for considerable size changes without cell proliferation. Histological evidence suggested that a fluid pressure-pump system (lymphatic, blood pressure) was the driving force that inflated the intestinal villi. The rates of cell proliferation were not elevated immediately after feeding but peaked 1 week later when small intestine size was already declining. In contrast to the current paradigm, we suggest that the small intestine is not part of the previously proposed 'pay-before-pumping' model. Instead, the size of the python's small intestine may be upregulated without major metabolic investment. It can occur even if the individual is energetically exhausted. An evolutionary perspective of the transitional epithelium mechanism suggests superior functionality compared with the pay-before-pumping model because it allows for long periods of fasting and depletion of energy reserves, while still enabling the snake to digest prey and absorb nutrients.

Effects of food shortage and oversupply on energy utilization, histology, and function of the gut in nestling song thrushes (Turdus philomelos).

We measured food intake, digestive efficiency, body mass increments, resting metabolic rate (RMR), carcass fat content, size and histological structure of the gut, and the rate of intestinal brush border uptake of l-proline in song thrush (Turdus philomelos) nestlings subjected to food shortage or food surplus under laboratory conditions. We assigned nestlings between 3 and 7 d of age to one of the following treatments: (1) food restriction, which resulted in a slowed growth at the rate found in undernourished, wild nestlings; (2) overfeeding, which totally suppressed begging; and (3) intermediate feeding. Threefold differences in energy consumption caused fivefold differences in body mass increments of the nestlings. Despite this, body mass-corrected RMR and intestinal mass were not affected by the feeding regime. The energy content of fecal output was highest in food-restricted birds, while their carcass fat content was lowest among treatment groups. Intestinal uptake rates of l-proline were low in the overfed and intermediate-fed young but significantly increased in the food-restricted birds, who attempted to maximize their rates of growth and development within the restrictive limits set by feeding regime. We noted a marked decrease of intestinal villi height in overfed birds as compared to intermediate-fed and food-restricted nestlings. We conclude that song thrush nestlings are characterized by a limited plasticity of their developmental program, which prohibits overfed nestlings from significantly up-regulating their gut function to accommodate increased food intake. This suggests that they already grew at a rate close to their physiological maximum. We suggest two interpretations: (1) under natural conditions, song thrush nestlings do not face frequent, unpredictable fluctuations in food abundance that could select for developmental plasticity, or (2) strong selection for uniform adult phenotypes prevents flexible developmental trajectories, which would result in a diversity of adult phenotypes.

Intestinal nutrient uptake measurements and tissue damage: validating the everted sleeves method.

The reliability of methods for nutrient uptake measurements across the intestinal epithelium relies on the integrity of the mucosal epithelium and the enterocytes. We tested effects of tissue handling during the "everted sleeves method" on the length of intestinal villi, the surface magnification, the circumference of the gut, and the thickness of the muscle layer in sunbirds (Nectarinia osea), chicken (Gallus gallus), and mice (Mus domesticus). The sunbird has thin and delicate intestinal villi that are greatly affected by the everted sleeves method. After eversion and incubation, villi lost 30% of their original length. The severe tissue damage coincides with uptake measurements for glucose that were an order of magnitude lower than in other nectar-feeding (nectarivorous) birds of similar body size. Tissue handling during the everted sleeves method had significant effects on morphometric parameters of chicken and mouse intestines, but on a light-microscopical level, the tissue integrity and the cytology of the enterocytes were not altered. Therefore, we think that the everted sleeves method renders reliable and reproducible measurements of nutrient uptake in those species. We conclude that a histological evaluation is necessary to assess the reliability of the method before it is applied to adults or to the developmental stage of any species.

Intestinal growth in altricial European starling (Sturnus vulgaris) and precocial Japanese quail (Coturnix coturnix japonica). A morphometric and cytokinetic study.

This paper introduces the comparison of altricial and precocial birds as a model system for the study of patterns of intestinal growth. It reports on comparative morphometric and cytokinetic studies of intestinal growth in altricial European starling (Sturnus vulgaris) and precocial Japanese quail (Coturnix coturnix japonica). Morphometric data at five gut segments of neonates and adults of both species are provided to evaluate the growth of the intestine. A double labelling technique combining 3H-thymidine autoradiography with 5-bromo-2'-deoxy-uridine immunohistochemistry gives labelling index, length of S-phase, and tissue turnover time for hatchlings and adults of both species. The results of morphometry show a similar pattern of intestinal growth in both species, a strong dependency of intestinal growth on body size, and a clear topographic separation of areas of cell proliferation from the functional mucosal epithelium. The results of the cytokinetic experiments indicate a constant length of the S-phase independent of species, development, and age. The 3H-thymidine labelling index is significantly higher in neonate quail than in neonate starling. Between adult animals of both species, the labelling index goes not differ significantly except for the duodenum which has a higher index in starling. The turnover time necessary to replace the mucosal epithelium is 3 days in hatchlings of both species and ranges between 10 and 17 days in adults. A diurnal pattern of cell proliferation, as previously reported in adult quail, is not present in neonate quail. Thus, differences in intestinal growth among altricial and precocial birds are primarily based on size differences of proliferation areas whilst cellular proliferation rates have only minor impact on intestinal growth. The short turnover time and the high rates of proliferation suggest that the intestine is a flexible organ that may be adjusted in size and function to the actual needs of the growing bird.

Structural responses of Japanese quail intestine to different diets.

Japanese quail were fed five diets of different nutrient composition and the structural responses of the intestinal tract were measured. Six morphometric variables were recorded. Depending on the diet, we found drastic changes in those factors affecting surface dimensions of the mucosa epithelium and the thickness of the muscle layers of the intestinal wall. We performed a principal component analysis to describe the interrelationship among the different variables and the response of the intestine to different diets. Two principal components were found accounting for surface and muscle layers respectively. Cytokinetic experiments (TdR/BrdU double labelling of S-phase nuclei) were performed to estimate the epithelial turnover time. We found a labelling index between 1.5% and 3% depending on the segment of the intestine. The length of the S-phase was found to be constant along the gut at 6.5 (+/- 2.5) hours. The epithelial turnover time, necessary to rebuild and adjust the intestine, ranged between 10 and 17 days. We discuss evolutionary ecology perspectives as well as applied poultry aspects of the data.

Comparative anatomy of the external and middle ear of palaeognathous birds.

This study provides new anatomical data, morphometric measurements, and functional hypotheses about the middle ear of paleognathous and a basal neognathous bird. The introduction discusses current theoretical concepts and basic functional approaches in vertebrate morphology. A cautious and somewhat skeptical evaluation of the techniques used, errors made, and personal experience gained in this study forms the background of the interpretation of the structural data. The comparative discussion extracts phylogenetic information from the structural data. The external ear opening of paleognathous species is large and unprotected. The auricular feathers show no structural specialization and provide only incomplete opercularization. No muscles insert into the external ear opening. Special attention has been paid to modifications in the cassowary's skin. The skin of its head has developed cavernous blood sinuses that may be flooded and thus inflate the head during booming display. The external auditory meatus of paleognathous birds is large, bends ventrally, and reaches the tympanic membrane from the ventral side. No peculiarities can be described. The osteology of the tympanic region is described in detail. The fusion of all bony elements and the ossification of connective tissue are important features of the avian middle ear region. The fusion of bone is a necessary prerequisite for extended pneumatization. The ossification of connective tissue, however, complicates morphological description since it deviates from morphologically defined bones. Especially in the neognathous button quail, most of the ventral wall of the middle ear cavity consists of ossified connective tissue; it also includes elements of the extracolumella. The fixation of the eardrum to the bony wall of the tympanic cavity is described in detail. The fixation includes the kinetic quadrate and loose connective tissue in the ventro-lateral part of the middle ear cavity. Movements of the bill must change the tension of the eardrum and thus affect the hearing of birds. The recesses of the middle ear cavity have been investigated using X-ray computed tomography. Using this technique, subsequent three-dimensional reconstruction provides unusual and unique insights into the anatomy of such "nonstructures" as air-filled cavities. It has been shown that three tympanic recesses are a character shared by all birds. Of more functional importance is the interaural pathway provided by the anterior tympanic recess and connecting the contralateral middle ear cavities. This structure is present in all recent and mesozoic birds. It has been suggested that the interaural pathway might function as a sound pressure gradient receptor. Physiological data are controversial but in many cases supportive.(ABSTRACT TRUNCATED AT 400 WORDS)