The jaw and hyoidean mechanism of the bullfrog tadpole during aqueous ventilation

1968 ◽  
Vol 46 (5) ◽  
pp. 1041-1052 ◽  
Author(s):  
Norman Gradwell
Keyword(s):  
Electrical Stimulation ◽  
Direct Observation ◽  
Buccal Cavity ◽  
Time Sequence ◽  
Lower Jaw ◽  
New Interpretation ◽  
Bullfrog Tadpole

Bullfrog tadpoles (above ca. 18 C) normally achieve branchial ventilation by the rhythmic pumping of water through the buccal cavity. This is facilitated by a coordination between the mandibular and hyoidean movements. Below 70 cycle/min only the lower jaw is active, but both jaws participate at higher frequencies. The jaw and hyoidean muscles and their time sequence were investigated by direct observation, electrical stimulation, lesion, and electromyography. A consideration of jaw ligaments has led to a new interpretation of the jaw mechanism.

The initiation of diving apnoea in the frog, Rana pipiens

1976 ◽  
Vol 64 (1) ◽  
pp. 25-38
Author(s):  
N. H. West ◽  
D. R. Jones
Keyword(s):  
Electrical Stimulation ◽  
Water Level ◽  
Rana Pipiens ◽  
Buccal Cavity ◽  
Respiratory Muscles ◽  
Normal Pattern ◽  
Water Head ◽  
Response To Water ◽  
Water Meniscus ◽  
Stimulation Of

1. Diving apnoea in Rana pipiens was initiated by submerging the external nares. As the water level was raised above the frog, both buccal and lung pressure increased by an amount corresponding to the water head. During submergence the external nares remained closed, although the apnoeic period was punctuated by ventilation movements which moved gas between the lungs and buccal cavity. 2. Bilateral section of the ophthalmic nerves did not alter the normal pattern of ventilation in air, although it often resulted in the intake of water into the buccal cavity on submergence. Introduction of water into the buccal cavity, either naturally as in denervates or by injection through a catheter in intact frogs, triggered sustained electromyographical activity in some respiratory muscles. 3. Electroneurograms recorded from the cut peripheral end of an ophthalmic nerve showed that receptors in the external narial region were stimulated by movement of a water meniscus across them. Activity could also be recorded in the ophthalmic nerve in response to water flow past the submerged nares. Punctate stimulation of the narial region confirmed that these receptors were mechanosensitive. 4. Bilateral electrical stimulation of the central ends of cut ophthalmic nerves in lightly anaesthetized frogs caused apnoea with a latency of less than 200 ms. The external nares remained closed throughout the period of stimulation although buccal pressure events, resembling underwater ventilation movements, occurred when stimulation was prolonged.

Cranial anatomy of tadpoles of five species of Scinax (Hylidae, Hylinae)

Zootaxa ◽  
2011 ◽  
Vol 2787 (1) ◽  
pp. 19 ◽  
Author(s):  
LEANDRO ALCALDE ◽  
FLORENCIA VERA CANDIOTI ◽  
FRANCISCO KOLENC ◽  
CLAUDIO BORTEIRO ◽  
DIEGO BALDO
Keyword(s):  
Buccal Cavity ◽  
Morphological Data ◽  
Sister Taxon ◽  
Anatomical Features ◽  
Interspecific Relationships ◽  
Lower Jaw ◽  
Lateral Ridge ◽  
Source Of Information

We studied the oral apparatus, buccal cavity and musculoskeletal features in tadpoles of five species of the genus Scinax (S. acuminatus, S. uruguayus, S. aff. pinima, S. aromothyella, and S. berthae). Observed variation is mainly related to intrageneric grouping. Scinax acuminatus (S. ruber clade, sister taxon of S. rostratus group) has a distinctive combination of a mental gap in the margin of oral papillae, straight labial teeth with few or absent cusps, processus muscularis acute and posteriorly directed, and m. subarcualis rectus I with two slips. Scinax uruguayus and S. aff. pinima (S. uruguayus group) have keratinized sheets ventrolateral to the lower jaw sheath, well-developed infralabial and lateral ridge papillae, robust jaw cartilages, cornua trabeculae with short and widely divergent free portions, processus articularis short and wide, processus muscularis thin and directed anteriorly. Scinax aromothyella and S. berthae (S. catharinae group) have poorly developed, non-colored spurs behind the lower jaw sheath, long and thin processus articularis, wide and rounded processus muscularis, and tripartite cartilago suprarostralis. Anatomical features described are congruent with current phylogenetic arrangements based on molecular, chromosomal, and morphological data, and provide a source of information that can be useful to solve interspecific relationships within Scinax.

Gnashing induced by electrical stimulation of rabbit brain cortex

1961 ◽  
Vol 200 (5) ◽  
pp. 916-918 ◽  
Author(s):  
Yojiro Kawamura ◽  
Shusaku Tsukamoto ◽  
Kiyokatsu Miyoshi
Keyword(s):  
Electrical Stimulation ◽  
High Frequency ◽  
Brain Cortex ◽  
Low Frequency ◽  
Rabbit Brain ◽  
Lower Jaw ◽  
Low Frequency Stimulation ◽  
Frequency Stimulation ◽  
Chewing Movement ◽  
Experimentally Induced

Gnashing was induced in rabbits by high-frequency cortical stimulation. The frequencies ranged from 60 to 1000 cycle/sec. Strictly circumscribed anteromedial cortical areas were responsive to stimulation. These loci are similar to those which induced chewing movements with low-frequency stimulation (30 cycle/ sec). Electrical stimulation within the above-described range induced gnashing of a constant rhythm of 3–4 cycle/sec that was almost independent of the stimulation frequency. The rate of experimentally induced gnashing is slower than the rate of experimentally induced chewing movements of 5–6 cycle/sec. Gnashing motion of the lower jaw consisted of the vertical and dominant lateral movements; the lateral deflection was more predominant than that of the chewing movement. Gnashing was readily induced with low-frequency stimulation after topical application of a 0.5% solution of strychnine nitrate on the cortical jaw motor area.

The function of the ventral velum during gill irrigation in Rana catesbeiana

1970 ◽  
Vol 48 (6) ◽  
pp. 1179-1186 ◽  
Author(s):  
Norman Gradwell
Keyword(s):  
Direct Observation ◽  
Rana Catesbeiana ◽  
Buccal Cavity ◽  
Maximum Volume ◽  
Gill Cavity ◽  
Valvular Function

The direct observation of the ventral velum in normally breathing tadpoles confirms earlier evidence for a valvular function of this structure during inspiration. The ventral velum also acts as a hydrofoil during expiration and as a mucus-secreting surface for the entrapment of suspended food particles.As the volume of water pumped per irrigation cycle is normally less than the maximum volume of the buccal cavity, it is unnecessary for the pharynx also to become filled with inspired water during the sinking of the buccal floor. Therefore the ventral velum's cyclic occlusion of the buccal cavity from the pharynx is no handicap to normal irrigation; on the contrary, it is a prerequisite for the efficiency of the pharyngeal pump.The dorsal velum does not participate in valvular activity, but deflects the respiratory current downward and inward to the gill cavity via gill clefts 2, 3, and 4. Therefore the strong flow pumped into the pharynx by buccal compression is prevented from impinging directly on the ciliated groove behind the dorsal velum and thereby interfering with the transport of food into the esophagus.

Memoirs: On Certain Features in the Development of the Alimentary Canal in Lepidosiren and Protopterus

1910 ◽  
Vol s2-54 (216) ◽  
pp. 483-518
Author(s):  
J. GRAHAM KERR
Keyword(s):  
Main Part ◽  
Alimentary Canal ◽  
Buccal Cavity ◽  
Ventral Side ◽  
Main Mass ◽  
Lower Jaw ◽  
Right Lobe ◽  
Dorsal Mesentery

1. The fore-gut first becomes folded off from the main mass of yolk-cells. 2. The pyloric valve arises by the hind end of the fore-gut being pushed back into the cavity oE the mid-gut. 3. The main mass of yolk-cells becomes gradually "modelled" into a spirally-coiled intestinal rudiment. 4. The main part of the buccal lining is developed in situ from large yolk-cells. 5. The part of the ventral side of the head, on which, are the olfactory rudiments, becomes enclosed in the buccal cavity by the development of the upper lips and by the forward growth of the lower jaw. 6. The olfactory opening becomes divided into anterior and posterior tiares by the apposition and fusion of the intermediate portion of its lips. 7. The thyroid arises as a solid downgrowth from the buccopharyngeal floor, which gradually becomes cut off from behind forwards. 8. The tongue is a primary tongue like that of Urodeles, but without gland-field. 9. The lung arises from a solid mid-ventral rudiment. 10. When the lung becomes bilobed, the (actual) right lobe is for a time small in size as compared with its fellow. 11. Complicated torsional processes take place during the development of the lung. 12. Through the dorsal mesentery becoming partially merged in the splanchnocoele roof, the lungs come to lie outside the splanchnocoele.

Hydrostatic pressures during normal ventilation in the bullfrog tadpole

1968 ◽  
Vol 46 (6) ◽  
pp. 1169-1174 ◽  
Author(s):  
Norman Gradwell ◽  
Valerie M. Pasztor
Keyword(s):  
Buccal Cavity ◽  
Ventilation System ◽  
Compression Stroke ◽  
Pressure Pump ◽  
Pharyngeal Pressure ◽  
Flow Through ◽  
Gill Cavity ◽  
Valvular Function ◽  
Bullfrog Tadpole ◽  
Normal Ventilation

A detailed description of the water flow through the ventilation system of the bullfrog tadpole has been facilitated by recording the time dependence of normal hydrostatic pressures in the system. The mouth and nasal intakes are discontinuous but a pharyngeal pressure pump to support the buccal pressure pump has been found to assist in maintaining a flow through the gill cavity. The alternate action of these pumps drives water into the gill cavity during almost the entire ventilation cycle and owes its efficiency to the occlusion between the buccal cavity and pharynx during the compression stroke of the pharyngeal pump. The need for a valvular function of the ventral velum has thus been demonstrated as it is the only structure between the buccal cavity and pharynx which can effect such cyclic occlusion.

The Paradox of Mytilus Muscle. A New Interpretation

1956 ◽  
Vol 33 (2) ◽  
pp. 295-310
Author(s):  
G. HOYLE ◽  
J. LOWY
Keyword(s):  
Electrical Stimulation ◽  
Electrical Activity ◽  
Smooth Muscles ◽  
Strong Support ◽  
Tonic Contraction ◽  
Mechanical Activity ◽  
Retractor Muscle ◽  
Pharmacological Interest ◽  
New Interpretation ◽  
Contraction And Relaxation

1. The mechanism of contraction and relaxation in the anterior byssus retractor muscle (A.B.R.M.) of the lamellibranch mollusc Mytilus edulis has been studied with refined stimulating and recording techniques. Two distinct types of response are present: phasic and tonic. The former can be evoked by all kinds of electrical stimulation, but the latter is most readily elicited by continuous direct current. 2. Serotonin (5-hydroxytryptamine) rapidly abolishes the tonic response, whilst leaving the phasic response practically unaffected for many hours. On electrical stimulation, a serotonin-treated muscle may show spontaneous electrical and mechanical activity, usually of a rhythmical nature. As the muscle is unable to destroy this drug the effects produced by it are likely to be of pharmacological interest only. 3. Electrical activity in the form of irregular volleys of muscle action potentials can be recorded from the intact A.B.R.M. and even after the nerves to the muscle have been cut. In such (externally) denervated preparations the spontaneous electrical activity is almost unaffected by a.c. stimulation but greatly increased by d.c. stimulation which evokes prolonged tonic contraction. 4. Stimulation of inhibitory nerves within the muscle quickly terminates a state of tonic contraction and at the same time reduces the electrical activity considerably. 5. An explanation is offered for the occurrence of electrical activity during relaxation of lamellibranch smooth muscles. The normal functioning of the A.B.R.M.is interpreted, and strong support is given to the tetanus hypothesis of tonic contraction.

Direct Observation of Heat Exchanger Deposits by Cross Sectioning

1967 ◽  
Vol 25 ◽  
pp. 364-365
Author(s):  
R. W. Anderson ◽  
D. L. Senecal
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Heat Exchanger ◽  
Direct Observation ◽  
Cross Sections ◽  
Preparation Method ◽  
Specimen Preparation ◽  
Flowing Water ◽  
Transmission Electron ◽  
Deposit Layer

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.

Application of a Simple Cold Stub to the Direct Observation of Frozen Hydrated Sand

1973 ◽  
Vol 31 ◽  
pp. 212-213
Author(s):  
John M. Wehrung ◽  
Richard J. Harniman
Keyword(s):  
United States ◽  
Surface Water ◽  
Direct Observation ◽  
Controlled Study ◽  
Clay Particles ◽  
Organic Debris ◽  
Rock Formations ◽  
Water Tables ◽  
Permeable Rock ◽  
Natural Means

Water tables in aquifer regions of the southwest United States are dropping off at a rate which is greater than can be replaced by natural means. It is estimated that by 1985 wells will run dry in this region unless adequate artificial recharging can be accomplished. Recharging with surface water is limited by the plugging of permeable rock formations underground by clay particles and organic debris.A controlled study was initiated in which sand grains were used as the rock formation and water with known clay concentrations as the recharge media. The plugging mechanism was investigated by direct observation in the SEM of frozen hydrated sand samples from selected depths.

Direct Observation of the Diffusionless β → β + ω Transformation in Titanium Alloys

1971 ◽  
Vol 29 ◽  
pp. 122-123
Author(s):  
N. E. Paton ◽  
D. de Fontaine ◽  
J. C. Williams
Keyword(s):  
Electron Microscope ◽  
Titanium Alloys ◽  
Direct Observation ◽  
Dark Field ◽  
X Ray Diffraction ◽  
Resistivity Measurements ◽  
Selected Area Electron Diffraction ◽  
Ti Alloys ◽  
Thin Foils ◽  
Field Device

The electron microscope has been used to study the diffusionless β → β + ω transformation occurring in certain titanium alloys at low temperatures. Evidence for such a transformation was obtained by Cometto et al by means of x-ray diffraction and resistivity measurements on a Ti-Nb alloy. The present work shows that this type of transformation can occur in several Ti alloys of suitable composition, and some of the details of the transformation are elucidated by means of direct observation in the electron microscope.Thin foils were examined in a Philips EM-300 electron microscope equipped with a uniaxial tilt, liquid nitrogen cooled, cold stage and a high resolution dark field device. Selected area electron diffraction was used to identify the phases present and the ω-phase was imaged in dark field by using a (101)ω reflection. Alloys were water quenched from 950°C, thinned, and mounted between copper grids to minimize temperature gradients in the foil.

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