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At least 19 recordsLinked to original sources
PubMed1977

Cellular and extracellular dehydration, and angiotensin as stimuli to drinking in the common iguana Iguana iguana.

1. After water deprivation, the iguana promptly drank slightly more than enough water to restore the body fluids to isotonicity even under conditions of hypervolaemia. 2. In response to systemic injections of hypertonic solutions of NaCl and sucrose, the iguana drank and retained enough water to dilute the injected load to isotonicity irrespective of whether water was offered immediately or after 3 hr, and irrespective of whether the solute was administered I.V. or I.P. 3. Hypertonic solutions to glucose, urea, sorbitol and KCl caused little drinking. 4. The long latencies to drinking after hypertonic loads, which were not dependent on the nature of the solute, the route of administration or the dosage, were shown not to be a result of slow distribution of the solute throughout the body fluids. 5. Clearance of injected solutes via renal and extra-renal (nasal salt gland) routes was negligible during the 6 hr experimental period. 6. Measurements of plasma [Na], haematocrit, osmotic pressure and inulin space showed that the iguana drank, in response to cellular dehydration, enough water to restore the intracellular fluid volume to normal. 7. We conclude that, in response to substances which dehydrate cells, the iguana regulates its body osmolality precisely and efficiently provided it is able to do so by drinking. In this respect the responses of the iguana are similar to those of the nephrectomized rat since, in the short term, both rely exclusively on drinking to restore cellular water to normal. 8. The iguana also drinks in response to extracellular dehydration produced by hyperoncotic peritoneal dialysis, and in response to I.P. angiotensin II.

Angiotensin II↗
PubMed1976

Nutritional osteodystrophy in captive green iguanas (Iguana iguana).

Captive lizards fed a variety of vegetarian and carnivorous diets frequently develop severe nutritional osteodystrophy. Five hatchling iguanas which were captive for 5 months and fed a diet low in calcium and phosphorus developed clinical signs and lesions typical of nutritional osteodystrophy in captive lizards. They had tetany with severe osteoporosis, pathologic fractures, and cartilaginous diaphyseal enlargements of long bones which either were associated with fractures or with intact bones. Hatchling and juvenile iguanas fed a similar diet low in calcium (0.1%) and phosphorus (0.2%) under experimental conditions developed hypocalcemia, tetany, osteoporosis with but adequate in phosphorus (1.1%) developed progressive hypocalcemia and severe osteopososis with pathologic fractures. Control iguanas fed a diet with adequate calcium (2.7%) and phosphours (1.1%) had well mineralized bones with wide cortices and thick metaphyseal trabeculae. Iguanas fed low calcium experimental diets whether low or adequate in phosphorus developed hypocalcemia with compensatory secondary hyperparathyroidism resulting in severe osteodystrophy similar to that reported in captive lizards.

Animal Nutritional Physiological Phenomena↗
PubMed1992

An anatomical investigation of the muscles of the pelvic outlet in iguanas (Iguanidae Iguana iguana) and varanus (Varanidae Varanus (dumerillii)) with special reference to their nerve supply.

Five pelvic halves from three male iguanas (Iguanidae Iguana iguana) and two pelvic halves from one male varanus (Varanidae Varanus (dumerillii)), were dissected in order to obtain detailed data on the relationship of the lumbosacral plexus and the muscles of the pelvic outlet. According to the positions of the passage of the metazonal nerves, the nerves can be divided into three groups: 1) the nerves passing dorsal to the caudofemoralis muscle, 2) the nerves passing between the caudofemoralis and the caudoischiadicus major, 3) the nerves passing ventral to the caudoischiadicus major. In consideration of the sites of origin from the lumbosacral plexus, a stratificational analysis can be proposed; group 1 arises craniodorsal to group 2, and group 3 caudoventral to group 2. It is suggested that the pelvic outlet muscles (caudofemoralis, quadratus caudae, obliquus cloacae, transversus cloacae profundus, retractor penis, caudoischiadicus major, and the caudoischiadicus minor) are derived from the ventral muscles of the posterior limb, and have moved caudally concomitant with the caudal migration of the cloaca.

Animals↗
PubMed1978

Behavior and electrical brain stimulation in the green iguana, Iguana iguana L. II. Stimulation effects.

Behavioral responses were electrically elicited in the brains of 21 green iguanas. At 518 stimulation sites, a limited number of behaviors could be reliably elicited. Except for some motor responses which had a forced appearance, they corresponded to the basic activity of green iguanas, exploratory behavior, display, defensive and escape-related behavior. Head-nodding displays were reliably elicited post stimulation when imminent escape was prevented experimentally but rarely during stimulation. Goal-directed behavior, i.e., feeding, drinking, mating and fighting behavior, were not elicited. The stimulation sites of frequently elicited behavioral responses revealed regional differences and some structural correlations. The majority of sites yielding defensive display responses were found in the hypothalamus, while dewlap display was more readily and widely elicited. Axial rotation and head-raising were elicited in a ventrothalamic zone extending into the tegmentum mesencephali. Tongue-flicking response sites were mostly concentrated in ventromedial areas of the tel-, di- and mesencephalon. Most escape-related responses were distributed unspecifically but the sites of violent flight responses were confined to the dorsal and lateral mesencephalon.

Animals↗
PubMed1976

Oral food processing in two herbivorous lizards, Iguana iguana (Iguanidae) and Uromastix aegyptius (Agamidae).

The anatomy and function of the feeding apparatus in Iguana iguana and Uromastix aegyptius were studied by dissection, cinematic and cineradiographic techniques. The feeding behavior of these species differs from that of insectivorous lizards in the cropping action involves movement of both the upper jaw around the atlantooccipital joint and the lower jaw around the mandibular joint; and in Uromastix only, streptostylic movement of the quadrate. Often movements of the whole head play a supplementary role in the cropping action. In both species the feeding apparatus has been modified to facilitate cropping. In Iguana the pleurodont dentition is multicusped and laterally compressed. Each tooth forms a shearing blade whose function does not require contact with other teeth. In Uromastix the dentition is acrodont and the cheek teeth are massive and lack cusps. Occlusion is necessary for shearing plant material. The skull system of Uromastix also has a number of modified structures which allow protraction and retraction of the lower jaw to facilitate cropping while maintaining a gape equivalent to that in Iguana. It is suggested that the differences in the feeding apparatus between Iguana and Uromastix are attributable to differeces in the mode of tooth replacement and implantation.

Animals↗
PubMed1978

The organization of central auditory pathways in a reptile, Iguana iguana.

The present experiments were designed to trace the central auditory pathways in an extant reptile, the New Worlkd lizard--Iguana iguana, utilizing anterograde axonal degeneration stained by the Fink-Heimer ('67) method and the retrograde axonal transport of horseradish peroxidase (LaVail and LaVail, '74). Beginning with the projections of the auditory portion of the VIIIth nerve, the ascending pathways were traced through successive relay nuclei to the telencephalon. The auditory portion of the VIIIth nerve projects to two nuclei in the dorsomedial medulla-nucleus angularis and nucleus magnocellularis medialis. These two nuclei together with a third cll group, nucleus magnocellularis lateralis (intercalated between nucleus angularis and nucleus magnocellularis medialis), have been referred to as the auditory tubercle in previous studies (cf. Miller, '75). The axonal degeneration following large lesions of the auditory tubercle and small lesions of nucleus angularis demonstrated the second order auditory pathways. Fibers leave nucleus angularis ventrally and travel to the ventral surface of the medulla where they cross the midline and ascend to the midbrain in pathways resembling the trapezoid body and the lateral lemniscus of mammals. Along these pathways, terminal arborizations of some fibers were seen in three lower brainstem nuclei while other fibers ascent to the midbrain and terminate in the central nucleus of the torus semicircularis. Experiments in which horseradish peroxidase injections were made in the torus semicircularis demonstrated that nucleus angularis is a primary source of second order auditory fibers to the midbrain and, in addition, that two of the lower brainstem targets of the auditory tubercle project to the torus semicircularis. These lower brainstem pathways were shown to be associated with the auditory system by electrophysiologically recording sound-evoked responses from clusters of cells in the torus semicircularis. Ascending fibers arising from the central nucleus of the torus semicircularis were followed rostrally where they entered the dorsal thalamus and terminated throughout nucleus medialis. Finally, a thalamotelencephalic auditory pathway was traced from nucleus medialis into the lateral forebrain bundle. Terminations of this pathway from nucleus medialis were seen in the medial dorsal ventricular ridge and in the striatum. It was concluded that the ascending auditory pathways of the iguana bear a remarkable resemblance to both the mammalian and avian auditory pathways from the level of the first order neurons in the VIIIth nerve to the level of the telencephalon. At the same time, there are important specializations of the auditory system in birds and mammals such as the development of particular lower brainstem nuclei. Nevertheless, a basic plan for the organization of the auditory system in terrestrial vertebrates can be recognized which invites comparisons with the vertebrate classes that remained in aquatic habitats...

Animals↗
PubMed1979

The fine structure of the parietal retinas of Anolis carolinensis and Iguana iguana.

An electron microscopic examination of the parietal retinas of Anolis carolinensis and Iguana iguana demonstrated within each retina (1) two distinct populations of neurons, (2) two populations of glia, and (3) a population of photoreceptors which could not be subdivided. A small population of very electron-dense cells, in many respects similar to photoreceptors, was also found in the iguana. Correspondingly dark processes were found in the plexiform layer of each retina. Parietal photoreceptors generally resemble cones of the lateral eye. Glial cells were sub-classified on the basis of the location of their somata and the disposition of their processes. Neurons were identified by virtue of their cytology and their reception of axosomatic ribbon synapses from unidentified plexiform layer processes. Neuronal subtypes were located on opposite sides of the plexiform layer. Neurons distal to that layer were found to project the initial segments of their processes into the plexiform layer parallel to its long axis, while neurons central to the plexiform layer projected axons centrally and dendrites radially into the plexiform layer. The existence of at least two neuronal populations and of interphotoreceptor synapses suggests that photosensory processing within the parietal retina may be more complex than previously assumed.

Animals↗
PubMed1976

Nucleotide sequence of 5 S ribosomal ribonucleic acid of Iguana iguana.

Cell cultures of the reptile Iguana iguana have been labeled with 32PO4(3-) and the resulting radioactive 5 S rRNA isolated. Enzymatic digests of the radioactive RNA were fractionated by standard procedures, and the products of the digestions sequenced. From the sequences of the oligonucleotides produced by enzymatic digestion of the Iguana 5 S rRNA it is possible to propose a primary sequence for this RNA which differs in only two positions (2 and 25) from the sequence known for mammalian 5 S rRNAs. This sequence is closer to that of mammals than is that of any other nonmammalian species yet examined.

Animals↗
PubMed1976

Fine structural changes of bone cells in experimental nutritional osteodystrophy of green iguanas.

Lizards, especially iguanids and varanids, frequently develop nutritional osteodystrophy in captivity, but its pathogenesis is incompletely understood. Green iguanas fed an experimental diet low in calcium (0.2%) and adequate in phosphorus (1.1%) developed severe osteoporosis characterized by flattened inactive osteoblasts, marked resorption of endosteal bone by large multinucleated osteoclasts, and pronounced resorption of cortical bone by osteocytic osteolysis. Iguanas fed an experimental diet low in both calcium (0.1%) and phosphorus (0.2%) developed osteoporosis with osteomalacia characterized by large active osteoblasts overlying wide osteoid seams, marked osteoclastic resorption of endosteal bone, and large osteocytic lacunae which had a prominent layer of osteoid. Osteocytes in iguanas fed the low calcium diets were small in relation to the size of their lacuanae and contained abundant microtubules, microfilaments and mitochondria but a paucity of rough endoplasmic reticulum. Mean ash content of tibias from iguanas fed the low calcium diets was lower, particularly in iguanas that developed severe oseomalacia, than in iguanas fed the control diet (2.7% calcium, 1.1% phosphorus). The ultrastructural evidence suggesting active bone formation, osteoclastic resorption, and osteocytic osteolysis seen in control iguanas was consistent with that of a young growing animal. The results of this investigation demonstrated that experimental iguanas fed diets low in calcium developed hypocalcemia and compensatory hyperparathyroidism resulting in progressive osteoporosis due to osteoclastic and osteocytic osteolysis.

Animals↗
PubMed1975

The connections and laminar organization ofthe optic tectum in a reptile (lguana iguana).

The goals of this study were: (1) to describe the total pattern of projections from the optic tectum of Iguana iguana and Pseudemys scripta; and (2) to describe the contributions of particular lamina of the Iguana's optic tectum to this total pattern. Lesions were made in the optic tectum of the Iguana which damaged either all or only certain tectal laminae and, for comparison with the Iguana, lesions in the turtle's optic tectum were made which involved all laminae. The anterograde degeneration resulting from these lesions was stained with the Fink-Heimer ('67) method. The total pattern of projections from the optic tectum in the Iguana and the turtle is similar to that reported for representatives of other vertebrate classes. That is, the optic tectum gives rise to ipsilateral ascending projections to pretectal nuclei, to nucleus rotundus and to nucleus geniculatus lateralis pars ventralis of the diencephalon and, in addition, to a contralateral ascending pathway which courses via the supraoptic decussation to the contralateral diencephalon. Tectotectal connections and several descending pathways were also recognized in each species. The descending pathways include ipsilateral tectobulbar and tecto-isthmi pathways and a contralateral predorsal bundle. Lesions which damaged only certain tectal laminae in the Iguana revealed a laminar organization of the efferent projections. A lesion restricted to the superficial retinal-recipient layers, stratum griseum et album superficiale, resulted in degeneration in only nucleus isthmi pars magnocellularis and nucleus geniculatus lateralis pars ventralis. A lesion which involved both the retinal-recipient layers and stratum griseum centrale resulted in degeneration in only one additional structure, nucleus rotundus. A small lesion involving the deep periventricular layers as well as the superficial layers produced degeneration in the predorsal bundle and the ipsilateral tectobulbar tract as well as in the structures receiving input from the more superficial layers. These results are compared to the results of similar analyses of the superior colliculus in mammals.

Animals↗
PubMed1992

Ultrastructure of an iguana fast twitch denervated muscle.

This ultrastructural study was undertaken to investigate the morphological changes which occur in the fast twitch gastrocnemius muscle of the reptile Iguana iguana after nerve section. It was found that initial degenerative alterations appeared in muscle fibers two weeks after denervation and progressed along the two months of the investigative period. They consisted of disorganization of contractile and sarcotubular elements and the appearance of autophagic vacuoles with mitochondrial debris. However, even two months after nerve section some myofibrils and mitochondria looked normal. Our results suggest that although the general course of denervation atrophy in iguana gastrocnemius is similar to that in other twitch muscles of vertebrates, the chronology of the process shows that iguana fast twitch skeletal muscles exhibit an intermediary position among the vertebrates in relation to their velocity of response to denervation.

Animals↗
PubMed1975

Comparative immunology of Galapagos iguana hemoglobins.

The antigenic properties of the major hemoglobin component of the Galapgaos iguanas were studied using second-approximation qualitative and quantitative immunochemical techniques. Phylogenetic distances, relative to the Galapagos marine iguana. Amblyrhynchus cristatus, were established on the basis of immunological cross-reactions.

Animals↗
PubMed1978

Immunochemical identity of the high and low molecular weight forms of Galapagos marine iguana hemoglobin.

1. Two forms of Galapagos marine iguana methemoglobin, with molecular weights of 140,000 and 70,000 daltons, were identified in iguana RBC lysates by Sephadex G-200 molecular sieve fractionation. 2. The 140,000 dalton ferric hemoglobin was isolated by DEAE-Sephadex A-50 ion-exchange chromatography and found to be pure by electrophoretic and immunological criteria. 3. Immunochemical analyses revealed the high and low molecular weight hemoglobins to be antigenically identical.

Animals↗
PubMed1975

Regulation of arterial blood pressure in the common green iguana.

Arterial blood pressure (ABP) responses to graded hemorrhage and passive head-up tilt were studied in restrained, anesthetized, and unanesthetized iguanas. The ABP fell slowly in response to hemorrhage up to a critical deficit of 35 plus or minus 19% of the estimated blood volume; the rate of ABP fall then increased nearly 40-fold to continued hemorrhage. Increased heart rate and decreased femoral arterial blood flow accompanied progressive hemorrhage. Propranolol (2-3 mug/kg) did not appreciably alter arterial pressure-hemorrhage curves but hemorrhage-induced increases in heart rate were diminished nearly 50%. Atropine had little effect on either the blood pressure or heart rate changes induced by hemorrhage. During passive tilts of 0-90 degrees carotid arterial pressure fell 33% before returning to control levels (2 min). Heart rate increased and femoral arterial blood flow and central venous pressure fell in response to head-up tilts. It is concluded that hemorrhage and passive head-up tilting can induce reflex cardiovascular changes that assist ABP regulation in iguanas.

Anesthesia↗