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At least 19 recordsLinked to original sources
PubMed1975

On the muscular fuel of the air sac in an air breathing fish.

The hyohyoideus muscle which is responsible for inflating and contracting the air sac in an air breathing fish, Amphipnous cuchia, belongs to white fibre type as it lacks muscle myoglobin. The muscle shows appreciable amount of glycogen and extracellular phospholipid globules. Staining of I bands in the muscle fibres with Alcian blue (1.0 less than or equal to pH less than or equal to 3.0) indicates presence of acid mucosubstances. The muscle does not show change in phospholipid content at the histochemical level but lowering of glycogen content (25 to 30%) when put to 51/2h of continuted physiological exercise. At the same time, increase in blood sugar level (20 to 30%) possibly indicates utilization of glycogen as the source of energy by the muscle. However, a clear cut priority of glycogen or phospholipid break down for energy source by the muscle could not be established.

Animals↗
PubMedDate not supplied

Evaluation of different procedures for processing avian air sac lavage fluid.

Air sac lavage has become a routine diagnostic tool used in pet birds; however, cytologic techniques for collection and handling of avian cells have not been reported. In this study, directed endoscopy was used to obtain the air sac washes. Different factors were compared that might affect final preservation of cell morphology, such as centrifugation speed, anticoagulant, storage temperature, time to processing, addition of glutaraldehyde to the sample, and addition of protein. The goal was to find the processing technique best suited for the evaluation of cells from air sac washes. The use of an anticoagulant did not influence cell quality. Optimal cell morphology was achieved when the sample was centrifuged at a speed of 1000 rpm (89.4 X g) and when prepared in less than an hour from the time of collection. Low temperature (5 C) tended to preserve cell quality better. The addition of protein (fetal bovine serum) helped to preserve cell quality and was of value if the sample storage time was greater than 30 min. The addition of glutaraldehyde resulted in a significant reduction in cell quality.

Air Sacs↗
PubMed1998

Differential air sac pressures in diving tufted ducks Aythya fuligula.

The air in the respiratory system of diving birds contains a large proportion of the body oxygen stores, but it must be in the lungs for gas exchange with blood to occur. To test the hypothesis that locomotion induces mixing of air sac air with lung air during dives, we measured differential pressures between the interclavicular and posterior thoracic air sacs in five diving tufted ducks Aythya fuligula. The peak differential pressure between posterior thoracic and interclavicular air sacs, 0.49+/-0.13 kPa (mean +/- s.d.), varied substantially during underwater paddling as indicated by gastrocnemius muscle activity. These data support the hypothesis that locomotion, perhaps through associated abdominal muscle activity, intermittently compresses the posterior air sacs more than the anterior ones. The result is differential pressure fluctuations that might induce the movement of air between air sacs and through the lungs during dives.

Abdominal Muscles↗
PubMed1985

Sources of carbon dioxide in penguin air sacs.

CO2 tensions in the caudal air sacs of birds cannot be quantitatively predicted by current models of avian respiration, mainly because the contribution of neopulmonic parabronchial gas exchange has not been determined. To overcome this problem we studied penguins that have purely paleopulmonic lungs. Three penguins were anesthetized, intubated, and ventilated at a constant respiratory rate and different tidal volumes (VT). PO2 and PCO2 were measured in arterial blood and end-expired, mixed-expired, interclavicular air sac, and caudal thoracic air sac gas. Interclavicular air sac and end-expired gas had similar compositions. Caudal thoracic air sac gas was intermediate in composition to end-expired and inspired gas, and its PCO2 was 1.5-3.5 times greater than the value predicted from reinhaled dead space. This difference between measured and predicted caudal thoracic air sac PCO2 increased with VT but showed no relationship to changes in dead space-to-VT ratio. The difference is not explained by stratification or diffusive gas exchange across air sac walls. The results can be explained by postulating that inspired gas passes over exchange surfaces on its path to caudal air sacs. This is unexpected in the purely paleopulmonic lungs of penguins and suggests that airflow may not be caudocranial in all paleopulmonic parabronchi.

Air Sacs↗
PubMed1976

Gas exchange in air sacs: contribution to respiratory gas exchange in ducks.

Air sac gas exchange was studied in ducks by measuring the rates of inert gas uptake and of O2 and CO2 equilibration in caudal thoracic air sac whose ventilation was prevented by surgival sealing of the ostia. The data were analyzed on a model incorporating three possible routes by which air sac gas could be exchanged with the surrounding tissue: (1) into the blood perfusing the air sac walls; (2) into the adjoining air sac via tissue membranes; (3) into the bronchial system of the lung via diffusion through lung tissue bordering upon the caudal thoracic air sac. Exchange rates of gases via the two latter paths were found to be small as compared with the first route. From application of model parameters to O2 and CO2 exchange in air sacs under physiological conditions the following conclusions were drawn: (1) the caudal thoracic air sac makes the major contribution to total gas exchange between air sacs and blood; (2) this exchange can account for less than 5% of total respiratory gas exchange; (3) the exchange is too small to account for the O2 and CO2 partial pressures in caudal thoracic air sacs of ducks. Other mechanisms like gas exchange in neopulmonic parabronchi, which conduct air to the caudal air sacs during inspiration or re-inspiration of dead space appear to play a more significant role in the deviation of O2 and CO2 partial pressures in the caudal air sacs from those in inspired air.

Air Sacs↗
PubMed2001

The influence of locomotion on air-sac pressures in little penguins.

Air-sac pressures have been reported to oscillate with wing beat in flying magpies and with foot paddling in diving ducks. We sought to determine the impact on air-sac pressure of wing beats during swimming and of the step cycle during walking in little penguins (Eudyptula minor). Fluctuations averaged 0.16+/-0.06 kPa in the interclavicular air sacs, but only 0.06+/-0.04 kPa in the posterior thoracic sac, generating a small differential pressure between sacs of 0.06+/-0.02 kPa (means +/- S.E.M., N=4). These fluctuations occurred at approximately 3 Hz and corresponded to wing beats during swimming, indicated by electromyograms from the pectoralis and supracoracoideus muscles. There was no abdominal muscle activity associated with swimming or exhalation, but the abdominal muscles were active with the step cycle in walking penguins, and oscillations in posterior air-sac pressure (0.08+/-0.038 kPa) occurred with steps. We conclude that high-frequency oscillations in differential air-sac pressure enhance access to and utilization of the O(2) stores in the air sacs during a dive.

Abdominal Muscles↗
PubMed2005

Tracheal branch repopulation precedes induction of the Drosophila dorsal air sac primordium.

The dorsal air sacs supply oxygen to the flight muscles of the Drosophila adult. This tracheal organ grows from an epithelial tube (the air sac primordium (ASP)) that arises during the third larval instar (L3) from a wing-disc-associated tracheal branch. Since the ASP is generated by a program of both morphogenesis and cell proliferation and since the larval tracheal branches are populated by cells that are terminally differentiated, the provenance of its progenitors has been uncertain. Here, we show that, although other larval tracheae are remodeled after L3, most tracheal branches in the tracheal metamere associated with the wing disc (Tr2) are precociously repopulated with imaginal tracheoblasts during L3. Concurrently, the larval cells in Tr2 undergo head involution defective (hid)-dependent programmed cell death. In BX-C mutant larvae, the tracheal branches of the Tr3 metamere are also repopulated during L3. Our results show that repopulation of the larval trachea is a prerequisite for FGF-dependent induction of cell proliferation and tubulogenesis in the ASP and that homeotic selector gene function is necessary for the temporal and spatial control of tracheal repopulation.

Animals↗
PubMed1978

Spectrographic analysis of laryngeal air sac resonance in rhesus monkey.

Laryngeal air sacs are circular out-pocketings, located in the hyoid bone with their ostium in the midline of the anterior part of the larynx. From previous cadaver studies of the rhesus monkey it was deduced that the function of the air sac is to act as a resonating chamber. The present study was designed to test this hypothesis. Recordings were made of three rhesus monkeys before and after surgical removal of the air sac. Spectrographic analysis of the monkeys' vocalizations indicated that differences in formant frequency characteristics between pre-and post-surgical recordings were negligible. This finding suggests that the laryngeal air sac does not play an important role in the resonant properties of the monkeys' vocal tracts.

Animals↗
PubMed1980

Incomplete gas mixing in air sacs of the duck.

During normal breathing, the CO2 concentration in caudal air sacs of birds is higher, and the O2 concentration lower, than expected on the basis of the known air flow pattern. We have experimentally tested two hypotheses which could explain this finding: (1) Preferential shunting of re-inspired dead space gas into caudal air sacs; (2) Incomplete mixing of inspired and residential air sac gas. - Different portions of the inspired air in anesthetized ducks were labeled by injecting a small bolus of argon (Ar) into the trachea. The resulting Ar concentration was recorded continuously in the caudal thoracic air sac at the ostium and in deeper regions.-The amount of Ar entering the sac was found to be independent of the volume inspired prior to injection of the label, and hypothesis (1) thus dismissed. However, during inspiration and subsequent expiration the Ar bolus was found to be neither perfectly mixed within the inspired gas nor with the air sac residential gas. More than 10 sec of breath-hold were necessary for air sac gas to approach an equilibrium value. Gas layering (stratification) in caudal air sacs gas is proposed to cause the high CO2 and low O2 levels during steady state breathing, as air sac residential gas equilibrates with a layer of dead space gas that enters the air sac on each breath and contains a higher CO2 and lower O2 concentration than the mixed inspirate.

Animals↗
PubMed2004

Vagal innervation of the air sacs in a songbird, Taenopygia guttata.

The air sacs of birds are thin-walled chambers connected to the lung that act as bellows in the ventilatory mechanism. Physiological evidence exists to suggest that they may contain receptors that are innervated by the vagus nerve, but no morphological study has examined the vagal innervation of these putative structures. To do this, we injected the cervical vagus nerve with choleragenoid and examined the innervation of the air sacs using light and confocal microscopy. We identified vagally innervated structures in the air sac wall that resemble the neuroepithelial bodies (NEBs) described in the airways of many vertebrates. Although NEBs have been proposed to have a dual chemoreceptive and mechanoreceptive role, their specific function in the air sacs of birds remains unclear.

Air Sacs↗
PubMedDate not supplied

Endoscopic gross anatomy findings of the thoracic air sac of the turkey.

The gross anatomy of the cranial thoracic air sacs was studied in the live turkey with a fiber-optic endoscope fitted with a video system. Thirty-five out of 39 (89.7%) of the turkeys had paired single thoracic air sacs with two ostia. The other 10.3% of the turkeys had paired cranial and caudal thoracic air sacs, each with a single ostium. The air flow pattern through the common thoracic air sac with two ostia is unknown. Furthermore, 42.3% of the turkeys with a single thoracic air sac had an invagination arising from the floor of the air sac that partially divided the single thoracic air sac creating a blind-ended sac. The blind sac formed by the invagination may trap small inhaled particulate matter.

Air Sacs↗
PubMedDate not supplied

Air sac cannula placement in birds.

Air sac cannulas are indicated in birds with upper respiratory obstruction or for ventilation during surgical procedures involving the head and neck. Proper technique, knowledge of potential complications, and an understanding of the indications for air sac tube placement are important for scientists, veterinarians, and technicians who work with birds.

Air Sacs↗
PubMed1999

An anatomical study of the respiratory air sacs in ostriches.

An accurate description of the number, location and relative position of the air sacs and their diverticula in the ostrich is essential for a better understanding of the pathogenesis of air sacculitis in this bird. The air sacs were studied in ten ostriches of varying ages by latex or silicone casting of the respiratory tract and dissection. Results revealed that the air sacs of the ostrich conform to the general pattern in birds. Cervical, lateral and medial clavicular, cranial and caudal thoracic, and abdominal air sacs are present. The left and right medial clavicular air sacs fuse with each other ventrally to the trachea to form a single, median compartment. A unique, large gastric diverticulum which covers the caudal aspects of the proventriculus and gizzard originates from the median compartment of the clavicular air sac. The lateral clavicular air sacs and their diverticula are similar to those of other bird species, with the exception that humeral diverticula are absent. Both abdominal air sacs are relatively small, with the left sac being the larger. Perirenal and femoral diverticula, similar to those found in other bird species, are present. However, the entire femur is aerated by the femoral diverticulum which also forms a large, subcutaneous division caudally and caudo-laterally to the femur. The presence of this subcutaneous part has practical implications for injury and intramuscular injections. The number and location of ostia connecting the air sacs to the bronchial tree are generally similar to those reported in other bird species.

Air Sacs↗
PubMed2003

NANC nerves in the respiratory air sac and branchial vasculature of the Indian catfish, Heteropneustes fossilis.

Gill and air sac of the Indian catfish Heteropneustes fossilis harbour a nerve network comprising an innervated system of neuroepithelial endocrine cells; the latter cells are found especially in the gill. A series of antibodies was used for the immunohistochemical detection of neurotransmitters of the neural non-adrenergic, non-cholinergic (NANC) systems such as the sensory neuropeptides (enkephalins), the inhibitory neuropeptide VIP and neuronal nitric oxide synthase (nNOS) responsible for nitric oxide (NO) production which is an inhibitory NANC neurotransmitter. NADPH-diaphorase (NADPH-d) histochemistry was used as marker of nNOS although it is not a specific indicator of constitutively-expressed NOS in gill and air sac tissues. A tyrosine hydroxylase antibody was used to investigate adrenergic innervation. Nitrergic and VIP-positive sensory innervation was found to be shared by gill and air sac. Immunohistochemistry revealed the presence of enkephalins, VIP, NOS and NADPH-d in nerves associated with branchial and air sac vasculature, and in the neuroendocrine cell systems of the gill. Adrenergic nerve fibers were found in some parts of the air sac vasculature. The origin of the nerve fibers remains unclear despite previous findings showing the presence of both NADPH-d and nNOS in the sensory system of the glossopharyngeal and vagus nerves including the branchial structure. Scarce faintly stained nNOS-positive neurons were located in the gill but were never detected in the air sac. These findings lead to the conclusion that a postganglionic innervation of the airways is absent. Mucous goblet cells in the gill were found to express nNOS and those located in the non-respiratory interlamellar areas of the air sac were densely innervated by nNOS-positive and VIP-positive nerve fibers. Our immunohistochemical studies demonstrate that most arteries of the gill and air sac share a NANC (basically nitrergic) innervation which strongly suggests that they are homologous structures.

Adrenergic Fibers↗
PubMedDate not supplied

The functions of laryngeal air sacs in primates: a new hypothesis.

A possible function of laryngeal air sacs in apes and gibbons was investigated by examining the relationships between air sac distribution, call rate, call duration and body weight in a phylogenetic context. The results suggest that lack of sacs in the smaller gibbons and in humans is a derived feature. Call parameters in primates, such as rate and duration, scaled to resting breathing rate (and therefore to body weight) only in species without air sacs, which appear to modify these relationships. Apes and larger gibbons may be able to produce fast extended call sequences without the risk of hyperventilating because they can re-breathe exhaled air from their air sacs. Humans may have lost air sacs during their evolutionary history because they are able to modify their speech breathing patterns and so reduce any tendency to hyperventilate.

Air Sacs↗
PubMedDate not supplied

Development of the thoracic air sacs of turkeys with age and rearing conditions.

Cytology and structure of the thoracic air sac of turkeys were investigated at four different ages (26-day embryo, 1 day, 2 wk, and 10 wk old) and two rearing conditions (isolation and commercial). Cytology was performed by guided fiberoptic endoscopy on the left thoracic air sac of each bird. The right thoracic air sac was sampled for light and electron microscopy. Heterophils were the most common nonepithelial cell found in air sac fluid. followed by macrophages and lymphocytes. Macrophages were most abundant in 1-day-old turkeys and turkeys raised in commercial conditions. The epithelium of the air sac consisted of squamous and cuboidal cells, with a few ciliated columnar and nonciliated columnar cells. Cuboidal cells had similar characteristics to type II pneumocytes. The mucociliary system was organized in tracts extended from the ostium to the posterior parts of the air sac. The number of ciliated tracts decreased with age, and the air sacs of commercial turkeys had a larger proportion of ciliated epithelium than did those of isolation birds. The epithelium may protect against disease by a structured mucociliary transport system, the production of surfactant, and phagocytosis of foreign particles. Differences in cytology and structure may reflect the maturation of the immune system and/or response to environment.

Aging↗